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Article

Seed Mixes in Landscape Design and Management: An Untapped Conservation Tool for Pollinators in Cities

by
Cláudia Fernandes
1,2,3,*,
Ana Medeiros
1,2,3,
Catarina Teixeira
1,2,3,
Miguel Porto
1,2,4,5,
Mafalda Xavier
3,
Sónia Ferreira
1,2,5 and
Ana Afonso
1,2
1
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Campus de Vairão, Universidade do Porto, 4485-661 Vairão, Portugal
2
BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, 4485-661 Vairão, Portugal
3
Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências, Universidade do Porto, 4099-002 Porto, Portugal
4
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Instituto Superior de Agronomia, Universidade de Lisboa, 1349-017 Lisboa, Portugal
5
EBM, Estação Biológica de Mértola, 7750-329 Mértola, Portugal
*
Author to whom correspondence should be addressed.
Land 2025, 14(7), 1477; https://doi.org/10.3390/land14071477
Submission received: 29 May 2025 / Revised: 11 July 2025 / Accepted: 14 July 2025 / Published: 16 July 2025
(This article belongs to the Special Issue Research in Urban Ecology: Application into Landscape Design and Green Infrastructure)
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Abstract

Urban green spaces are increasingly recognized as important habitats for pollinators, and wildflower seed mixes marketed as pollinator-friendly are gaining popularity, though their actual conservation value remains poorly understood. This study provides the first systematic screening of commercially available seed mixes in Portugal, evaluating their taxonomic composition, origin, life cycle traits, and potential to support pollinator communities. A total of 229 seed mixes were identified. Although these have a predominance of native species (median 86%), the taxonomic diversity was limited, with 91% of mixes comprising species from only one or two families, predominantly Poaceae and Fabaceae, potentially restricting the range of floral resources available to pollinators. Only 21 seed mixes met the criteria for being pollinator-friendly, based on a three-step decision tree prioritizing native species, extended flowering periods, and visual diversity. These showed the highest percentage of native species (median 87%) and a greater representation of flowering plants. However, 76% of all mixes still included at least one non-native species, although none is considered invasive. Perennial species dominated all seed mix types, indicating the potential for the long-term persistence of wildflower meadows in urban spaces. Despite their promise, the ecological quality and transparency of the seed mix composition remain inconsistent, with limited certification or information on species origin. This highlights the need for clearer labeling, regulatory guidance, and ecologically informed formulations. Seed mixes, if properly designed and implemented, represent a largely untapped yet cost-effective tool for enhancing the pollinator habitats and biodiversity within urban landscapes.

1. Introduction

1.1. Pollination: From an Ecosystem Service Toward a Wider Public Understanding of Human Welfare

Human activities profoundly impact ecosystems and biodiversity, with far-reaching consequences for society. Preserving biodiversity is crucial for bolstering ecosystem resilience, as various ecosystem services, including pollination, underpin essential aspects of human well-being, such as food, water, health, and energy security [1,2]. Pollination, a vital ecosystem service, sustains more than 75 percent of global food crop types [3], reinforces plant diversity [4,5], enhances crop productivity [6], and ensures genetic variability while also maintaining the delicate balance of ecosystem networks [3,7]. Crucially, pollination benefits extend to both agricultural fields and urban green spaces, guaranteeing food security and human welfare by facilitating crop pollination [8]. Although abiotic factors such as wind and water contribute to pollination, it is primarily animals, particularly insects, that mediate this process. However, numerous insect pollinator groups are experiencing declines in abundance and diversity [4,9] due to various factors, including industrialization, human expansion, and climate change [9,10,11,12]. Given the critical role of pollinators in plant diversity, declines in their richness and abundance threaten ecosystem functions, with potentially catastrophic consequences in the near future [13,14]. The crucial importance of pollination is explicitly acknowledged in the Nature Restoration Regulation [15], which includes a dedicated article setting a specific target to reverse the decline of pollinator populations by 2030 and ensure an increasing trend thereafter. This target is supported by a mandatory methodology for the regular monitoring of pollinators, highlighting pollination as a central concern within the broader framework of ecosystem restoration.
To counteract the ongoing decline of pollinators, it is crucial to implement strategies that combine multiple complementary approaches, such as restoring semi-natural habitats [16,17]. In this context, urban green spaces are emerging as key components of pollinator conservation efforts [18,19,20,21,22]. These environments not only provide essential resources, such as nectar, pollen, and nesting sites, but also serve as ecological corridors that help maintain connectivity between fragmented habitats [23]. Recent studies (e.g., Płaskonka et al. [24] and Schueller et al. [18]) indicate that urban green spaces have a much greater capacity to support pollinator biodiversity than previously thought, emphasizing their potential as refuges in increasingly urbanized landscapes.

1.2. Urban Green Spaces to Support Pollinator Conservation

As cities grow denser, urban green spaces are shrinking and becoming more fragmented. Urbanization impacts biodiversity by causing habitat loss, breaking up ecosystems, reducing population sizes, and diminishing genetic diversity [25,26]. Hence, maintaining ecological connectivity between parks, gardens, vacant lots, or any other type of green space aids pollinator conservation and promotes biodiversity and ecosystem services, benefiting nature and humans [27,28,29]. For instance, community gardens have been found to exhibit similar pollinator assemblages as rural areas, highlighting the potential of urban environments as refuges for insect pollinators [30,31]. Small informal green spaces like tree pits can play a surprisingly significant role in supporting a diverse range of wildflower species within the city [30,32]. These spaces are, therefore, important for implementing measures aimed at conserving pollinator biodiversity and sustaining viable populations, which are essential for preserving the valuable ecological services these organisms provide [33,34,35].
Most of the traditional herbaceous covers in urban green spaces have low plant species diversity and high disturbance regimes, such as frequent mowing, which could be impactful to the biodiversity of insects. Planting seed mixes with a rich variety of flowers can significantly enhance the diversity of pollinators in an area [19,36,37]. Research suggests that both generalist pollinators, which can feed on many types of flowers, and specialist species, which rely on specific plants, thrive when floral diversity increases [38]. A varied selection of flowering plants provides pollinators with a more balanced and nutritious diet, supporting their health and reproduction [38]. Given that many insect pollinators depend on multiple plant species throughout their life cycles, creating diverse floral landscapes can be a crucial strategy for sustaining and enhancing urban and rural pollinator populations.
In Europe, efforts to promote biodiversity and raise awareness about the conservation of native fauna and flora have been increasing. Municipalities, associations, and other organizations have played a key role in implementing initiatives that reach diverse audiences. As a result, several European countries have developed guidelines and specific actions to protect biodiversity and pollinators, specifically. These initiatives not only support ecological health but also foster greater public awareness of the essential ecosystem services provided by pollinators [33], for example, through the promotion of urban wildflower meadows, as seen in projects like Poland’s Flowering Meadows Program [39,40] or the No Mow May campaign in England and Ireland [41,42].
In parallel with these policy efforts, seed mixes for biodiverse wildflower meadows have gained attention as a conservation tool for pollinators in cities. Their potential, however, extends beyond ecological benefits. The careful selection of native and site-adapted species in seed mixes can also play a strategic role in landscape management and maintenance [43,44]. From reducing mowing frequency to improving the resilience to drought and pest pressures, well-designed seed mixtures can optimize long-term management regimes, especially in resource-constrained urban contexts. Despite this, the management implications of seed mixes remain underexplored in both research and practice, representing a critical but overlooked dimension in urban green infrastructure planning.
Biodiverse wildflower meadows also make a meaningful contribution to human well-being. Research has shown that colorful meadows are generally perceived as more visually appealing, enhancing people’s appreciation for urban biodiversity [45,46]. In contrast to highly manicured lawns, these dynamic landscapes, with prolonged and varied blooming periods, tend to foster stronger emotional connections to nature. Interestingly, people often interpret a high floral abundance and color diversity as indicators of biodiversity, even when the actual species richness is low [47]. In addition to their esthetic appeal, diverse wildflower meadows can reshape how urban green spaces are perceived. As public awareness of their ecological value increases, such as their role in supporting pollinators and reducing maintenance costs, there tends to be greater acceptance of a more naturalistic or “messy” look [48]. While flower colors are perceived differently by pollinators than by humans [49,50], the visual richness provided by taxonomically diverse blooms simultaneously enhances the ecological performance and strengthens public engagement. Integrating these meadows into urban design and management strategies can therefore promote both pollinator conservation and human psychological benefits in urban environments.

1.3. Commercially Available Wildflower Seed Mixes

Seeding urban green spaces with commercially available wildflower seed mixes offers a simple and effective method for creating habitats for pollinators [17]. The market now offers an increasing variety of wildflower seed mixes tailored for different purposes. However, there is uncertainty about how many of these mixes effectively support pollinator populations while catering to other urban ecosystem services. Several challenges are commonly associated with pollinator-friendly wildflower seed mixes, raising concerns about their availability, composition, and ecological suitability. One key issue is that pollinator-friendly wildflower seed mixes are relatively scarce and often more expensive [17,51]. Additionally, many wildflower seed mixes labeled as beneficial for pollinators contain high percentages of non-native species [51]. These exotic plants, besides being potentially invasive themselves, may not provide the necessary resources for native pollinators and, in some cases, could promote invasive species that threaten local ecosystems [17]. Even when wildflower seed mixes contain native species, it is likely that they have not been sourced from local populations, which is crucial since seeds with a local provenance are better adapted genetically to regional conditions and are more resilient to local pests and diseases. In addition, using seeds collected in different regions is a source of genetic pollution to the native plant populations, which can cause negative impacts on the indigenous populations by hybridization and the loss of genetic diversity [52].
Another concern is misleading labeling. Many seed packets marketed as beneficial for wildlife feature images of bees, butterflies, and colorful flowers, but their actual composition may not provide the best resources for pollinators. Ensuring that mixes support pollinators effectively requires a season-long flower availability, with a diverse selection of plant species that offer a range of shapes, colors, and bloom times [53]. A well-designed mix should promote continuous flowering throughout the seasons, attracting a wide variety of insect pollinators. As research suggests, greater plant diversity leads to higher insect diversity [5,53], reinforcing the importance of carefully selecting seed mixes that truly benefit both pollinators and urban ecosystems.
To analyze the potential of the use of wildflower seed mixes in urban green spaces with a pollinator promotion goal, this study was developed with three main objectives: (1) the general characterization of commercially available seed mixes in Portugal, (2) the identification and analysis of wildflower seed mixes, and (3) the evaluation of wildflower seed mixes for pollinator’s advantageous effects. We seek to answer three primary questions: (1) What seed mixes are available on the market? (2) How does the content of seed mixes correspond to their advertised purpose regarding pollinators? (3) Are the available seed mixes pollinator-friendly and esthetically appealing for use in urban green spaces?

2. Materials and Methods

2.1. Seed Mixes Selection

This study comprehensively screened flower seed mixes available in the Portuguese market. The search was carried out online during February and March 2023, utilizing the first 50 results in Google search (keyword: misturas de sementes) for brands selling flower seed mixes in Portugal. Given that this is a commercial product operating within a niche market lacking an official aggregator or dedicated database for mix sellers, Google was identified as the most effective tool to access the widest range of potential sources. Validation of the results was carried out through phone interviews with 16 farmers’ cooperatives. As a result, 17 brands commercializing seed mixes in Portugal were confirmed, all of which had available catalogues detailing the composition and intended uses of the mixes.
To identify pollinator-friendly seed mixes suitable for use in urban green spaces, a decision tree was developed (Figure 1) and applied in three phases. First, all commercially available seed mixes were analyzed. Next, the focus narrowed to wildflower seed mixes, excluding those solely composed of grasses, not fit for the purpose (e.g., if not showcasing keywords such as meadow, flower, urban, or pollinators), and not specifying forbs taxa. Finally, in the third phase, the selection was further refined to identify pollinator-friendly wildflower seed mixes. This was achieved by applying the criteria proposed by Nota et al. [51], prioritizing native species and extended flowering periods. Additionally, the selected mixes were evaluated for their esthetic potential in urban green spaces, considering the color of the blooms.

2.2. Data Variables and Analysis

The seed mixes were categorized based on the following variables: (i) intended use, (ii) botanical composition (family and lower taxa available), (iii) native status (native or non-native), (iv) life cycle (annual, biennial, or perennial), (v) flowering period, (vi) flowering color diversity, and (vii) cost–value (kilograms per unit cost). Mixes’ intended use was taken from the brand catalogues. Seed mixes available were categorized into four categories regarding their intended use: (1) pollinator-friendly habitats—seed mixes specifically supporting bees, butterflies, and other pollinators, (2) urban green spaces (UGSs)—seed mixes intended for recreational areas such as lawns and gardens, (3) pastures—seed mixes intended for animal feeding, (4) agriculture—seed mixes intended for food production labeled as intended for Orchards (including Olive Groves) and Vineyards, (5) forest—seed mixes for forests, and (6) ecological restoration—seed mixes focused on degraded habitats.
Taxonomic information for vascular plants (family, species, and/or common name) was recorded for each mix. However, the variability in the labeling of mix compositions created challenges in specifying and registering species data. Since many provide only common names, a standardization of scientific names was needed. Entries without a scientific name should include at least a genus-level designation (e.g., “Oat” → Avena sp. L., Poaceae). If the common name clearly refers to a specific species, the most likely scientific name can be inferred (e.g., “Crimson clover” → Trifolium incarnatum L., Fabaceae).
The data for native status and life cycle variables were derived from Flora-On website [54]. A verification of synonyms was performed on the World Flora Online (WFO) Plant List [55]. This way, the accepted scientific name for all taxa (families, genera, species, etc.) was confirmed, and the existence of records on Flora-On under different names was checked. The cost and package weight were consulted from the catalogue or website, considering various package sizes available for each mix.
The wildflower seed mixes were analyzed further to determine which had the longest flowering period—in this case, blooming for at least six consecutive months. In the final stage, the pollinator-friendly seed mixes were also assessed for flower color diversity to evaluate their esthetic potential. Data on flowering periods and flower colors were sourced from the Flora-On website [46]. Microsoft Excel was used to compile and organize the data, perform calculations, and generate graphs (Figure 4, Figure 5 and Figure 6). The Sankey plot (Figure 2) was created using SankeyMATIC [56]. An Upset plot of intended uses of seed mixes (Figure 3) was created in RStudio (2024.12.1 + 563 “Kousa Dogwood” for windows) using the package upsetjs [57]. Principal Component Analysis (PCA) was conducted to investigate multivariate relationships among taxa richness, proportion of native species, proportion of perennial species, intended use, flowering period, and floral color diversity (Figure 7), using the R packages corrr [58], FactoMineR [59], ggplot2 [60], ggfortify [61], gridExtra [62], and factoextra [63].

3. Results and Discussion

3.1. What Is in the Mix?

A total of 229 seed mixes were commercially available in Portugal, distributed and/or produced by 17 companies (Figure 2). Of these seed mixes, 11% (n = 26) are classified as wildflower seed mixes (WSMs), meaning they contain forbs and specify the taxa composition. Among the remaining 203 seed mixes, 50 consist exclusively of graminoids (Poaceae), 125 are intended for agricultural use (primarily composed of Poaceae and Fabaceae), and 28 do not specify the composition of forbs.
A deeper analysis of the wildflower seed mixes revealed that 21 were pollinator-friendly, as they were primarily composed of native species and had prolonged blooming periods (≥6 months). The results reveal that the national seed mix market in Portugal is still poorly aligned with pollination goals, as only a very small proportion (9%) contain pollinator-friendly wildflowers suitable for urban green spaces. The following sections provide a detailed analysis of the selected variables for each seed mix category: commercially available seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly wildflower seed mixes (PWSMs).
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Figure 2. The general characterization of commercial seed mixes (SMs) available showing the process of finding wildflower seed mixes (WSMs) and pollinator-friendly wildflower seed mixes (PWSMs). Keywords * green space, garden, bees, pollinators, flowers, and meadow.
Figure 2. The general characterization of commercial seed mixes (SMs) available showing the process of finding wildflower seed mixes (WSMs) and pollinator-friendly wildflower seed mixes (PWSMs). Keywords * green space, garden, bees, pollinators, flowers, and meadow.
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3.2. Seed Mixes’ Intended Use and Cost–Value

In the first phase, the main intended use of mixes was analyzed (Figure 3). Of the total mixes, 88% were formulated with only one goal stated. Few wildflower seed mixes are marketed specifically to support pollinators (≈1%), with the majority being intended for pastures (45%), and around 32% are designated for UGSs. The remaining seed mixes are intended for agricultural landscapes (6%), ecological restoration (4%), and forests (1%). Considering the remaining 12% of mixes indicated for multiple uses (≥2 uses) (Figure 3), the most common combination refers to UGSs and pastures (≈5% of mixes). Several combinations include pollinator promotion; however, they represent a very small percentage of the seed mixes (≈3.5%). Hence, most of the seed mixes are designed and marketed with a single intended use, reflecting the limited market demand for multifunctional or ecologically targeted products.
Although few seed mixes specify their price openly (n = 40), the available flower seed mixes on the market exhibit a price bias depending on their designated use. The price per kilogram (in euros) was variable among and within designated uses. The highest average prices (mean ± standard deviation) were found in mixes marketed for promoting pollinators (200.0 EUR/Kg ± 0.0), pastures (88.4 EUR/Kg ± 111.4), and urban green spaces (UGSs) (63.1 ± 88.4). In contrast, the lowest average prices were observed in mixes intended for agriculture (11.0 EUR/Kg ± 0.4), forests (11.0 EUR/Kg ± 0.4), and ecological restoration (10.6 EUR/Kg ± NA). Mixes for UGSs register significant differences between mixes for lawns, costing on average 14.6 EUR/Kg ± 16.4, and mixes for gardens, reaching up to 92.6 EUR/Kg ± 98.3. Hence, we conclude that mixes specified as good at attracting pollinators and with a more diverse composition, especially catering to UGSs, are significantly more expensive, which might discourage their use by the consumers.
The price was also calculated for the three groups of seed mixes (SM, WSM, and PWSM). On average, SMs were priced at EUR 54/kg, WSMs at EUR 87/kg, and PWSMs at EUR 116/kg. Consequently, seed mixes with a greater potential to establish pollinator-friendly wildflower meadows in urban green spaces are significantly more expensive, with prices approximately being double.
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Figure 3. An Upset plot illustrating the combinations of intended uses for the analyzed seed mixes. The matrix at the bottom of the plot displays all possible combinations of intended uses across six categories (pastures, UGSs—urban green spaces, agriculture, restoration, forest, and pollinators). Each filled circle represents a use included in a particular combination, and each column of filled circles corresponds to one combination of uses. The vertical bars at the top show the intersection size, meaning the number of seed mixes corresponding to each combination of uses. The horizontal bars on the left show the total number of seed mixes that mention each use at least once, whether on its own or combined with other uses (i.e., the size of each individual use category).
Figure 3. An Upset plot illustrating the combinations of intended uses for the analyzed seed mixes. The matrix at the bottom of the plot displays all possible combinations of intended uses across six categories (pastures, UGSs—urban green spaces, agriculture, restoration, forest, and pollinators). Each filled circle represents a use included in a particular combination, and each column of filled circles corresponds to one combination of uses. The vertical bars at the top show the intersection size, meaning the number of seed mixes corresponding to each combination of uses. The horizontal bars on the left show the total number of seed mixes that mention each use at least once, whether on its own or combined with other uses (i.e., the size of each individual use category).
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3.3. Seed Mixes’ Taxa Composition, Native Status, and Life Cycle

The results show a significant limitation in terms of the taxonomic identification across the seed mixes analyzed. Specifically, 11 mixes (5% of the 229 records) provide no information regarding their composition or use a vague term such as “diverse flowers”. Additionally, 161 mixes (70%) do not fully disclose all constituent species: (i) in 94 mixes (41%) constituent species are referred to either by a common name or genus; (ii) 58 mixes (25%) include a vague description, e.g., “perennial legumes” or “annual grasses”, identifying solely at the family level; and (iii) in 9 mixes (4%) descriptors such as “other species” were also found, further inhibiting the seed mixes’ composition analysis.
Despite these limitations in taxonomic disclosure, the commercially available seed mixes included species from 41 plant families (n = 211). However, although forty-one families were identified across all mixes, the majority contained only one (31%) or two families (60%; Figure 4a). Therefore, one striking limitation of the potential of seed mixes to pollinators is the low diversity of families observed in SMs.
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Figure 4. The taxa composition for seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly seed mixes (PWSMs) in terms of the following: (a) the number of families, (b) number of species, (c) top families, and (d) top species.
Figure 4. The taxa composition for seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly seed mixes (PWSMs) in terms of the following: (a) the number of families, (b) number of species, (c) top families, and (d) top species.
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In the mixes where only one family was found, 80% of them were Poaceae, while 20% were Fabaceae. Poaceae and Fabaceae were the most prevalent families across all mixes (Figure 4c). While these families play vital roles in the life cycle of many pollinators, providing food and nesting resources [64,65], their limited flower trait diversity may restrict their appeal to a broader range of pollinator species adapted to distinct flower shapes [66,67]. Poaceae and Fabaceae might also be limited in terms of their esthetic potential for humans compared with other forbs. Asteraceae was in the third place for all the sets and is considered in the literature as one of the most successful flowering plant families as they are widely used in landscaping [68].
Studies regarding seed mixes aimed at pollinators usually show a preference for flowers within three families: Asteraceae, Apiaceae, and Fabaceae [17]. Our results do not confirm a preference for Apiaceae in the Portuguese seed mixes market. However, there are important differences between countries and locations, depending on the pollinator species, plant communities, and geographical extension of the study regions. For example, Nichols et al. [38], in a research project conducted in the UK, point out that Fabaceae, particularly Trifolium (clovers), might not be as important as other misrepresented plant species such as Asteraceae, Apiaceae, and Geraniaceae. In Germany, the most important host plants of oligolectic bees belong to the Asteraceae and Fabaceae families, followed by the Brassicaceae and Lamiaceae families [69]. Families with showy flowers good for pollinators in Italian urban green spaces belong to the botanical families of Amaryllidaceae, Dipsacaceae, Malvacee, Asteraceae, Apiaceae, Ranunculaceae, Lamiaceae, Caryophyllaceae, and Campanulaceae [70].
A comprehensive study specifically linking wildflower plant species and their main pollinators in Portugal is still lacking. However, recent research has begun to address related topics [71]. In particular, Carvalho et al. [71] compared pollination networks across different ecological restoration strategies, such as active restoration and natural (spontaneous) regeneration. The results showed that both approaches supported the recovery of pollination services, although active restoration led to a faster and more structured recovery, with notable differences in the dominant pollinators among sites: honeybees played a key role in naturally regenerated areas, bumblebees were more important in abandoned quarries, and wild bees dominated in actively restored sites. This study highlights the need to consider the diversity of wild pollinators and to ensure a continuous supply of floral resources throughout the year when designing restoration or conservation strategies.
WSMs and PWSMs tend to have a higher number of families and species represented in their composition (Figure 4b). On the other side of the spectrum, seed mixes with 10 to 20, 20 to 30, and over 30 species are more numerous in WSMs and PWSMs. The number of mixes containing more than 30 species shows a clear increase from SMs to WSMs and PWSMs (Figure 4b). This diversity of plant species is a very positive result, as it supports various groups of pollinators, each adapted to different plant families and flower shapes, including bees, wasps, flies, beetles, and moths [3,7].
The top species used in the seed mixes are more varied between the analysis sets (Figure 4d). Even so, Lolium perenne L. (Poaceae), Festuca arundinacea Schreb. (Poaceae), and Festuca rubra L. (Poaceae) are common between all sets. Trifolium repens L. is also a popular choice in WSMs and PWSMs.
Seed mixes (SMs) tend to be highly polarized, containing either a very high percentage of native or non-native species. On average, SM have a median of 86% native and 14% non-native species. As shown in Figure 5b, 68% of SMs are composed entirely of native species, while 6% are entirely non-native. In contrast, WSMs have a median of 84% native and 16% non-native species, with a more even distribution across the native–non-native gradient. Most WSMs contain between 50% and 90% of native species. PWSMs exhibit an even higher native species content, with a median of 87% native and 13% non-native species (Figure 5a). The majority of PWSMs fall within the 75–90% native and 10–25% non-native range. Notably, five mixes in the WSM and PWSM groups are composed entirely of native species. However, at least 76% of PWSMs have at least one exotic species. The most common exotic species are Onobrychis viciifolia Scop. (Fabaceae), Trifolium incarnatum L. (Fabaceae), Thymus vulgaris L. (Lamiaceae), Medicago sativa L. (Fabaceae), and Centaurea cyanus L. (Asteraceae). All non-native species present in the mixes were assessed for their invasive potential. None of the recorded non-native species were identified as invasive.
Regarding life cycle compositions (Figure 5c), the SM contains a median of 71% perennials, followed by 24% annuals and a negligible percentage of biennials. Similar trends are observed in WSMs and PWSMs, with perennials consistently dominating. These results suggest that wildflower meadows are likely to persist over time, as annual and biennial species are more prone to disappearances. Nevertheless, the lack of composition descriptions for many seed mixes poses challenges.
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Figure 5. (a) Native status distribution (native and non-native species percentage) calculated per mix for seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly seed mixes (PWSMs), (b) proportion of native vs. non-native species considering 8 classes of percentages, (c) life cycle distribution calculated per mix for seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly seed mixes (PWSMs), and (d) proportion of perennials, annuals, and biannuals considering 8 classes of percentages.
Figure 5. (a) Native status distribution (native and non-native species percentage) calculated per mix for seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly seed mixes (PWSMs), (b) proportion of native vs. non-native species considering 8 classes of percentages, (c) life cycle distribution calculated per mix for seed mixes (SMs), wildflower seed mixes (WSMs), and pollinator-friendly seed mixes (PWSMs), and (d) proportion of perennials, annuals, and biannuals considering 8 classes of percentages.
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Sowing a mix of wildflower seeds without the knowledge of the species content could lead to the introduction of exotic and possibly invasive plant species, placing the community stability at risk by introducing new interactions and competition with native species [72,73]. Thus, it has been recommended to use regional plants and seeds to maximize the success of the seed mix and avoid the negative impacts of introducing exotic species to the region [53,73,74]. Specific mixes of wildflower seeds can be composed to target specific regions, using the knowledge of the local native plant communities to adapt the mix content. Likewise, appropriate maintenance regimes are essential to seed mixes to fulfil their ecological potential beyond the taxa composition, native status, and life cycle. Maintenance regimes, particularly the mowing frequency, have a direct impact on the pollinator diversity and abundance [31,44,75,76]. Without informed management, in which the mowing frequency is aligned with the plant phenology, the success of seed mixes may be limited.
The certification of the seed origin is another relevant point for discussion. In this study, it was not possible to assess the origin of the seed mixes with certainty, due to the absence of information or the lack of verifiable sources. However, this is an essential matter. It can be problematic to sow seeds harvested in another country, even if they are from the same species because species exhibit a genetically structured variability across different geographic regions. In severe cases, this genetic contamination could negatively impact wild populations [52]. In relation to this, there should also be regulations regarding the region where each seed mix can be used. For example, it is highly debatable to use a mix of plants typical of the northern part of the country in a garden in the Algarve (southern Portugal), even if the necessary abiotic conditions for the species are met given the very distinct climatic conditions.

3.4. Seed Mixes’ Flowering Period and Color Diversity

Overall PWSMs presented a total of nine different colors, plus one color category designated as “multicolor” for specific taxa that can showcase a diversified array of colors, such as Viola cornuta L. (Violaceae), Lathyrus odoratus L. (Fabaceae), or Phlox drummondii Hook. (Polemoniaceae). Results show that half the mixes have up to five colors present, 15% have one or two colors, and 35% have three to five colors (Figure 6). The reduced number of colors in some PWSMs was unexpected. A deeper analysis showed that the least diverse mix (Mix 21) was advertised as a meadow for landscaping containing only three species, from which two were Poaceae with a low bloom interest, resulting in only one forb with a notorious bloom (a Fabaceae), although the three are native. Mixes with only two colors were labeled as intended for dry meadows or ecological restoration, which appears inconsistent with their intended function. Although seed mixes for these purposes often prioritize native species adapted to local conditions (83% and 86% natives, respectively), sometimes resulting in a lower species or color diversity compared to ornamental wildflower mixes, a well-designed mix should still include a variety of taxa to support biodiversity and ecosystem resilience. Again, appropriate maintenance practices are essential to fully express the ecological potential of seed mixes, including extended blooming periods and color diversity [77]. Inappropriate mowing, whether too frequent or poorly timed, can prevent key species from flowering, thereby diminishing both their visual appeal and ecological function [76,78].
Conversely, seed mixes with a higher color diversity (Mix 1 and 2) were labeled as having a native taxa composition of 86% and 100%, respectively (Table 1). Despite containing an average of 26 species, none of these mixes explicitly indicate a suitability for urban green spaces. The predominance of annual species in Mix 1 suggests a limited long-term meadow persistence, whereas the latter may be particularly beneficial for green spaces in coastal environments. Additionally, a mix with nine color categories, Mix 3, comprises 23 species, of which only 54% are native.
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Figure 6. The flowering color analysis for the pollinator-friendly wildflower seed mixes (PWSMs) ranked from most to least colors throughout the year.
Figure 6. The flowering color analysis for the pollinator-friendly wildflower seed mixes (PWSMs) ranked from most to least colors throughout the year.
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Interestingly, seed mixes containing multicolored species included at least six distinct colors and had a median species richness of 24. This highlights a fundamental distinction between mixes explicitly designed to maximize diversity and those with less emphasis on species and color diversity. Based on this observation, we hypothesize that color diversity is strongly correlated with species diversity. To test this hypothesis, we applied a linear regression model, which revealed a strong positive correlation between the color diversity and species richness in PFSMs (r ≈ 0.8).
The PCA of PWSMs (Figure 7) shows that the cumulative proportion of Component 1 (38%) and Component 2 (27%) accounts for 65% of the total variance. Overall, the PCA reveals four distinct clusters. The first cluster indicates that mixes intended for ecological restoration (green) are characterized by higher proportions of perennial and native species. The second cluster includes seed mixes intended for agriculture and forestry (yellow), which are positioned in opposition to most of the variables analyzed in this study. A third cluster groups mixes designed for pollinators, pastures, and urban green spaces (purple), suggesting some overlap in their composition and intended functions. Lastly, a fourth cluster brings together the variables of the flowering period, flowering diversity, and taxa richness (pink), which appear to be strongly correlated with one another.
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Figure 7. PCA displaying four clusters of PWSM based on correlations between six variables: taxa richness, percentage of natives, percentage of perennials, intended use (pastures, urban green spaces—UGSs, forests, agriculture, restoration, and pollinators), flowering period (Bloom_Eval), and flowering color diversity (Bloom_Colors).
Figure 7. PCA displaying four clusters of PWSM based on correlations between six variables: taxa richness, percentage of natives, percentage of perennials, intended use (pastures, urban green spaces—UGSs, forests, agriculture, restoration, and pollinators), flowering period (Bloom_Eval), and flowering color diversity (Bloom_Colors).
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4. Conclusions

Efforts to conserve pollinators have driven the development of flower seed mixes aimed at attracting and supporting pollinator communities in urban green spaces. This study systematically screened seed mixes available in the Portuguese market (SM), identifying 21 pollinator-friendly wildflower mixes (PWSMs) through a three-phase decision tree prioritizing native species, extended flowering periods, and visual appeal.
The composition of SMs is highly heterogeneous and marked by several limitations. The taxonomic diversity is generally low; 91% of seed mixes include only one or two plant families, primarily Poaceae and Fabaceae, reducing the variety of floral resources for pollinators. Although most mixes contain a higher proportion of native species, 76% include at least one non-native species. Even so, all seed mixes are dominated by perennials, suggesting a good potential for long-term meadow persistence.
While PWSMs tend to be more diverse and visually appealing, their high cost may limit a broader implementation. These findings highlight the need for improved labeling, ecologically informed formulations, and coordinated strategies to promote seed mixes that are diverse, native-rich, and functionally beneficial for urban biodiversity.

4.1. Regulatory Frameworks

Regulatory frameworks for establishing habitats using various wildflower seed mixes exhibit significant variability across countries, contingent upon the type and timing of the implementation. In numerous countries, there is a conspicuous absence of support or regulation under nature conservation laws regarding the management of such habitats [36,79]. While the utilization of native seeds is advocated, once a flower seed mix enters the market, oversight diminishes substantially, resulting in a dearth of legal and conservation guidelines and constraints [79]. Ensuring transparency and accountability in the flower seed mix industry necessitates European-level regulations mandating the disclosure of the seed origin, the taxonomic identity, and the potential risk of unassisted propagation into natural habitats. Achieving this demands a comprehensive understanding of the intricate ecological relationships involved, coupled with stringent control and regulation measures governing the selection, application, and timing of flower seed mixes in urban green spaces. Such measures are essential not only for enhancing conservation efforts and ecosystem health but also for safeguarding human well-being and the sustainability of urban environments. Additionally, many products lack transparent labeling regarding the species composition and origin, which prevents the further analysis of the seed source.

4.2. Limitations and Future Research

One key limitation of this study is the dynamic nature of the seed mix market, which undergoes frequent changes with the introduction of new products. For instance, in recent years, products such as “flower bombs” have become available. These were excluded from our analysis as they appear to be primarily marketed toward children, given their colorful and appealing packaging, and may not be a practical option for large-scale urban green spaces. Additionally, a significant drawback of such products is the lack of detailed composition specifications, a broader issue observed across many seed mixes. Some products provide only generic information, listing the taxa at the genus level or using ambiguous common names. Even when scientific names are included, they often contain errors or are outdated.
A key area for future research is a more in-depth investigation into the native status and provenance of the seeds. Notably, the current native status analysis excluded the Portuguese archipelagos of the Azores and Madeira, which have very distinct native plant communities and are much less resilient to invasive species, with many examples of species that are native to continental Portugal being invasive in the archipelagos. Future studies should incorporate these regions to provide a more complete and representative national assessment. Although no invasive species were identified in the analyzed mixes, this only applies to continental Portugal, and a broader analysis that includes the archipelagos could disprove this finding. Adding to this, many mixes contained exotic species with unspecified or unidentified origins. Given that several brands operate on a multinational scale, the commercial availability of invasive species in seed mixes in Portugal could become a concern over time. While some brands highlight the importance of native species and environmentally friendly practices, their expansion across multiple geographic regions raises questions about the credibility of these claims. These challenges underscore the complexities of data analysis in this field and highlight the need for the further scrutiny of seed mix compositions and sourcing.
Beyond questions of provenance and invasive risk, future work should also evaluate the ecological performance of the species included in these mixes. In particular, it is important to assess which plant species and families best support diverse pollinator communities in Portugal and how their flowering periods contribute to providing continuous floral resources throughout the year. These insights could inform the development of seed mixes that are better adapted to the Portuguese context and encourage the creation of new products that are both ecologically appropriate and more effective in supporting pollinator conservation.
Another limitation of this study is the flower blooming analysis, as it did not account for the relative volume of each color due to the inconsistent availability of taxa composition percentages. However, the esthetic appeal of wildflower seed mixes is a crucial factor in the context of urban green spaces. Future research could involve germination trials to better assess both the visual characteristics of these mixes and their long-term viability. This approach would also enhance the value–cost analysis by considering the longevity of flowering meadows, distinguishing between mixes that are self-sustaining over time and those that initially perform well but decline after a few years.
This study emphasizes the importance of species-rich and ecologically informed seed mixes in supporting pollinator diversity in urban environments. However, further research is needed to evaluate how different seed mix compositions affect the operational aspects of urban green space maintenance, such as the irrigation demand, mowing regimes, and weed suppression. Although factors like the soil texture, pH, and watering requirements are essential for effective implementation, this information is often missing from product specifications provided by suppliers.
Understanding how seed mixes interact with local management regimes is crucial to ensure their long-term functionality. Without adequate maintenance, even well-designed mixtures may fail due to ecological succession, competition with invasive species, or incompatibility with site conditions. Investigating these dynamics would strengthen the case for seed mixes not only as a conservation tool but also as a practical strategy for aligning biodiversity goals with economic and logistical feasibility. Future studies should adopt an interdisciplinary approach that connects the ecological performance with real-world maintenance practices, particularly under the diverse environmental conditions found across mainland Portugal and the islands. Overall, wildflower seed mixes represent an untapped opportunity to address biodiversity concerns, benefiting ecosystems and human well-being. Effective market control and regulation are crucial to promoting pollinators and safeguarding ecosystem health, ensuring the positive impact of these mixes on biodiversity.

Author Contributions

Conceptualization, C.F., S.F. and A.A.; methodology, C.F., S.F., A.M., M.X., C.T. and A.A.; formal analysis, C.F., A.M. and A.A.; data curation, C.F., A.M., C.T., M.P., M.X. and A.A.; writing—original draft preparation, C.F., A.M., S.F. and A.A.; writing—review and editing, C.F., A.M., C.T., M.P., M.X., S.F. and A.A.; visualization, C.F. and A.M.; supervision, C.F. and S.F. All authors have read and agreed to the published version of the manuscript.

Funding

This research was co-funded by the project NORTE-01-0246-FEDER-000063, supported by the Norte Portugal Regional Operational Programme (NORTE2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). MP was supported by Portuguese national funds through FCT in the scope of Norma Transitória—DL57/2016/CP1440/CT0017 (https://doi.org/10.54499/DL57/2016/CP1440/CT0017). SF was funded by the FCT through the program “Stimulus of Scientific Employment, Individual Support—3rd Edition” (https://doi.org/10.54499/2020.03526.CEECIND/CP1601/CP1649/CT0007). CT was funded by the Education for Biodiversity Conservation Chair—a project funded by Fundação Belmiro de Azevedo (FBA) and FCT.

Data Availability Statement

The datasets presented in this article are not readily available because the data are part of an ongoing study. Requests to access the datasets should be directed to the corresponding author.

Acknowledgments

The authors would like to thank the companies that, when contacted, kindly provided detailed information about the mixes they commercialize.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
SMsSeed Mixes
WSMsWildflower Seed Mixes
PWSMsPollinator-Friendly Wildflower Seed Mixes

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Land 14 01477 g001
Figure 1. The decision tree for selecting pollinator-friendly seed mixes available in the Portuguese market.
Figure 1. The decision tree for selecting pollinator-friendly seed mixes available in the Portuguese market.
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Table 1. Pollinator-friendly wildflower seed mixes and their characterization using analyzed variables. Flowering period: excellent—blooms all year around; very good—blooms 9 to 11 months; and good—blooms 6 to 8 months.
Table 1. Pollinator-friendly wildflower seed mixes and their characterization using analyzed variables. Flowering period: excellent—blooms all year around; very good—blooms 9 to 11 months; and good—blooms 6 to 8 months.
Mix IDBrandTaxa RichnessNatives (%)Lyfe Cycle
(% of Perennials)		Forbs (%)Flowering PeriodFlowering ColorsIntended Use
1A30874380Excellent10Pollinators/UGS/Pastures
2A271006785Excellent10UGS/Pastures
3B26546985Excellent9UGS
4A32916381Very Good8UGS/Pastures
5A38957987Excellent8Pollinators/UGS
6A35917180Very Good8UGS/Pastures
7A278530100Excellent8Pollinators/UGS/Pastures
8C167510044Excellent7Restoration
9C18565689Very Good7UGS
10C13698562Good6Restoration
11D96711100Good5Pollinators/UGS/Pastures
Agriculture/Forests
12B86363100Very Good5UGS
13A475075Good4UGS/Pastures
14C12929258Excellent4Restoration
15D7571462Good4Pollinators/UGS/Pastures
Agriculture/Forests
16B139277100Very Good4UGS
17C71008629Good3Restoration
18B510010020Good3UGS
19E6836733Good2UGS
20C710010029Good2Restoration
21B310010033Good1UGS
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MDPI and ACS Style

Fernandes, C.; Medeiros, A.; Teixeira, C.; Porto, M.; Xavier, M.; Ferreira, S.; Afonso, A. Seed Mixes in Landscape Design and Management: An Untapped Conservation Tool for Pollinators in Cities. Land 2025, 14, 1477. https://doi.org/10.3390/land14071477

AMA Style

Fernandes C, Medeiros A, Teixeira C, Porto M, Xavier M, Ferreira S, Afonso A. Seed Mixes in Landscape Design and Management: An Untapped Conservation Tool for Pollinators in Cities. Land. 2025; 14(7):1477. https://doi.org/10.3390/land14071477

Chicago/Turabian Style

Fernandes, Cláudia, Ana Medeiros, Catarina Teixeira, Miguel Porto, Mafalda Xavier, Sónia Ferreira, and Ana Afonso. 2025. "Seed Mixes in Landscape Design and Management: An Untapped Conservation Tool for Pollinators in Cities" Land 14, no. 7: 1477. https://doi.org/10.3390/land14071477

APA Style

Fernandes, C., Medeiros, A., Teixeira, C., Porto, M., Xavier, M., Ferreira, S., & Afonso, A. (2025). Seed Mixes in Landscape Design and Management: An Untapped Conservation Tool for Pollinators in Cities. Land, 14(7), 1477. https://doi.org/10.3390/land14071477

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