Development of Edible Flower Production and the Prospects of Modern Production Technology

Abstract

The consumption of edible flowers is gaining global popularity due to their culinary appeal, vibrant colors, and health-promoting compounds. Traditional production methods—including wild collection, open-field cultivation, and greenhouse systems—offer limited control over environmental factors, often resulting in inconsistent yield, quality, and safety. To address these limitations, plant factories with artificial lighting (PFALs) have emerged as a promising technology for producing high-quality edible flowers year-round in controlled environments. This review explores the evolution of edible flower cultivation, from conventional methods to PFALs, and highlights key environmental factors—light, temperature, and nutrient management—that influence growth, flowering, and phytochemical profiles. Special attention is given to how light intensity, spectrum, and photoperiod affect morphogenesis and metabolite accumulation, and how nutrient solution composition, particularly nitrogen form and EC levels, modulates flowering and plant health. While recent studies have demonstrated the potential of PFALs in cultivating species such as calendula, nasturtium, and marigold, research remains limited for many commercially relevant species. The review identifies current challenges, such as high operational costs and knowledge gaps in species-specific protocols, and outlines future research directions aimed at improving efficiency, optimizing quality, and expanding market viability. PFALs offer a transformative opportunity for the edible flower industry by integrating precision agriculture with consumer demand for safe, functional, and visually appealing food products.

1. Introduction

As people become increasingly health-conscious, there is a growing interest in consuming nutritious foods. This trend has brought new attention to edible flowers, which were traditionally appreciated only for their visual and aromatic appeal. Historically, the consumption of flowers has been practiced across many regions worldwide. Valued for their vibrant colors and distinctive scents, flowers are widely used as garnishes, flavorings, colorants, and food ingredients. For example, dandelion (Taraxacum officinale) flowers are batter-dipped and fried in the United States [1], while tea plant (Camellia sinensis) leaves are consumed as vegetables in Nepal [2]. Blue pea flowers (Clitoria ternatea) are employed as a natural colorant in rice cooking in Malaysia [3]. In India, dried calendula petals (Calendula officinalis) serve as cheese colorants or substitutes for saffron [4]. Similarly, carpet geranium (Geranium incanum) is consumed fresh or cooked in South Africa [5]. In addition to their aesthetic value, many edible flowers offer significant nutritional benefits. They are rich in bioactive compounds and phytochemicals, including phenolic acids, flavonoids, and anthocyanins, along with pigments such as carotenoids (as shown in

Table 1. Health-beneficial compounds reported in some edible flower species.

Plant Species	Key Compound(s) Reported	Approx. Quantity x	Sources
Calendula	β-carotene Total phenol	0.85 mg gFW−1, 61.01 mg Catechol gFW−1	[8]
African marigold	Total phenolics Total flavonoids	48.55 mg GAE gDW−1 132.42 mg QUE gDW−1	[9]
Nasturtium	Total phenolics Total flavonoids	26.55 mg GAE gDW−1 39.46 ± 2.25 mg QUE gDW–1	[9]
Pansy (Viola × wittrockiana)	Total anthocyanins	2.42–4.52 mg gFW−1	[10]
Viola (Viola tricolor)	Total phenolics	0–0.19 mg GAE gFW−1	[11]
Rose (Rosa spp.)	Total phenolics Total flavonoids Anthocyanins	3.94–18.93 mg GAE gFW−1 0.38–2.06 mg QE gFW−1 0–5.72 mg C3G gFW−1	[12]
Borage (Borago officinalis)	Total carotenoids Total phenolics	1.81 mg β-carotene gDW−1 15.10 mg gDW−1	[13] [14]
Cornflower (Centaurea cyanus)	Total phenolics Total flavonoids	19.5–26.6 mg GAE gDW−1 16.9 mg QE gDW−1	[15]
Cosmos (Cosmos sulphureus)	Total carotenoids Total phenol	18.8 µg gFW−1 86.99 mg Catechol gFW−1	[8]

^x The values were recalculated from the original sources to standardize them to a fresh- or dry-weight basis.

), as well as nitrogen-containing and organosulfur compounds [6]. For example, the phenolic compounds are the most frequently quantified metabolites in edible flowers. The total phenolic content (dry-weight basis) in African marigold (Tagetes erecta) (48.55 mg GAE gDW⁻¹) and nasturtium (Tropaeolum majus) (26.55 mg GAE gDW⁻¹) was higher than that in the commonly consumed vegetables, such as tomato (2.9–5.0 mg GAE g DW⁻¹) and spinach (9.3–13.0 mg GAE gDW⁻¹) [7]. Because the studies in Table 1 mix fresh- and dry-weight-based results and use different calibration standards (e.g., GAE, catechol, QE, C3G), these values are not directly comparable across species.

The chemical compounds provide edible flowers with various biological and functional properties, including antioxidant, immunomodulatory, antibacterial, anti-inflammatory, antiallergic, cardioprotective, hepatoprotective, and neuroprotective effects. Consequently, some edible flowers have also been utilized as medicinal plants. For instance, ethanolic extracts of African marigold, Cosmos, Coral vine (Antigonon leptopus), and Bougainvillea (Bougainvillea glabra) have been studied for their potential to suppress human cancer cell proliferation related to the digestive system. The results indicated that extracts from T. erecta, C. sulphureus, and B. glabra inhibited pancreatic lipase activity, while A. leptopus exhibited efficacy against gastric adenocarcinoma and bladder cancer cells [16].

Edible flowers have become a fashionable and expanding niche market in various countries, including the United Kingdom, Portugal, and Australia [17]. This market expansion is driven by rising consumer demand and growing interest from professional chefs seeking high-quality edible flower products. However, the production of edible flowers continues to face several challenges, many of which are similar to those encountered in vegetable and fruit cultivation. These include inconsistent product quality, vulnerability to pests and diseases, and concerns over chemical residues from conventional pesticide use.

With the growing demand for edible flowers, there is an urgent need for advanced cultivation systems that can ensure consistent yield, superior quality, and product safety. PFALs represent a promising solution, offering fully controlled environments that allow growers to precisely manage light, temperature, humidity, CO₂, and nutrients—factors that directly influence flower growth and quality. Although PFAL technology has been successfully applied to leafy vegetables and herbs, its potential for edible flower production is only beginning to be explored.

Figure 1 presents an integrated four-core framework for edible-flower production: (i) Cultivation Technologies and Systems, (ii) Bioactive Value and Health Benefits, (iii) Sustainability and Compliance, and (iv) Market and Economics. Two-way arrows indicate mutual influence. Cultivation settings shape quality and safety. Market requirements and pricing feedback to production specs and costs. Sustainability constraints (energy, water, GHG, waste, food safety) guide system design while closed-loop practices reduce impacts. Together, these cores determine the central outcomes: yield, quality, profit, and footprint.

Against this framework, this review aims to provide an overview of edible flower production, with a focus on the application of PFALs as advanced, closed, and fully controlled cultivation systems that use artificial lighting as the light source. It summarizes key environmental factors, particularly light, temperature, and nutrient solution, that influence growth, flowering, and quality. Unlike prior reviews that primarily emphasize nutritional or health-promoting compounds, this review focuses on cultivation systems and operational considerations. The review also highlights recent research on edible flower cultivation in PFALs and identifies current challenges and future research directions to support sustainable and commercially viable production.

2. Development of Edible Flower Production

2.1. Wild Collecting

Before edible flowers were cultivated as an agricultural practice, they were usually picked from the wild and used for cooking or traditional medicine. When edible flowers are collected from the wild, there is a risk of mistakenly harvesting toxic or inedible species that belong to the same plant family or have a similar appearance [18]. In addition, there are risks of contamination from soil and air. Plants can absorb and store heavy metals from the soil [19]. Both essential (e.g., cobalt (Co), copper (Cu), iron (Fe), and zinc (Zn)) and nonessential heavy metals (e.g., cadmium (Cd), lead (Pb), and arsenic (As)) can be accumulated in edible parts such as leaves, flowers, and fruits. However, non-essential heavy metals are highly toxic and can harm living organisms. Air pollution is another concern, especially in areas near roads or industrial zones, where emissions from vehicles and factories may contaminate the flowers collected from the surrounding environment.

2.2. Open-Field Farming

As agricultural practices developed, edible flowers began to be cultivated in open fields, primarily for ornamental use rather than for consumption. These plants were later introduced into culinary use due to their colors, flavors, and health-promoting compounds [20]. Due to the increase in consumer demand for safe food, edible flower production in open fields is increasingly encouraged to follow organic farming regulations. In the European Union, this is enforced by strict regulations like EU Organic Regulation 2018/848 [21], which govern the use of pesticides and synthetic fertilizers to ensure high product quality and safety. However, organic farming regulations for edible flowers vary significantly across different countries. Some nations, unlike the EU, may have less stringent guidelines or even lack specific regulations for edible flower cultivation, leading to disparities in safety and quality.

Without organic practice regulations, soil-based cultivation can lead to problems like heavy metal contamination and soil-borne diseases, as mentioned earlier. Additionally, there is a risk of nutrient leaching into the ground, which reduces fertilizer efficiency and may contribute to environmental pollution [22]. Furthermore, open-field farming’s direct exposure to weather conditions significantly impacts both the quantity and quality of the harvest. For example, temperature fluctuations can either accelerate or delay flowering, as observed in chrysanthemum (Chrysanthemum morifolium) [23,24] and impatiens (Impatiens sp.) [25]. Moreover, heat stress can influence the physiological responses of rhododendron (Rhododendron × hybridum), leading to a decline in chlorophyll and carotenoid contents [26]. Open-field cultivation carries a risk of pest and disease outbreaks, which can necessitate the use of chemical pesticides and consequently lead to possible chemical residues on the harvested products.

2.3. Greenhouse Cultivation

To reduce environmental variability and pest risk, growers began using greenhouse structures for edible flower production. In the early stages of using greenhouses for edible flower cultivation, soil was still commonly used as the growing medium. The primary purpose of the greenhouse at that time was to protect crops from adverse weather conditions. Later, substrate culture using pots was introduced, helping to reduce the risks of soil-borne diseases and contamination. Switching to greenhouse cultivation for flower production offers several advantages. It helps optimize labor efficiency and the use of production facilities, allows for an extended growing season, and increases the commercial value of flowers [27]. Moreover, well-managed greenhouse environments can help reduce environmental impacts [28].

At the same time, fertilizer application methods—including hydroponics—were also improved, allowing nutrients to be delivered more efficiently during cultivation. Although hydroponic cultivation of edible flowers is still limited, there have been reports of successful production in particular species such as chrysanthemum [29], African marigold [30], and nasturtium [31]. Greenhouses enable better control of environmental factors, leading to improved flower uniformity and extended seasons. However, this system allows for partial environmental control and still faces challenges such as light fluctuation, seasonal temperature swings, and inconsistent levels of bioactive compounds, mainly when flowers are grown in suboptimal seasons.

To overcome these limitations, fully enclosed and highly controllable production systems, known as PFALs, have emerged as the most advanced form of controlled-environment agriculture (CEA). PFALs allow precise regulation of key environmental factors such as light, temperature, and nutrient supply, offering the potential to produce high-quality edible flowers consistently, regardless of season.

3. Plant Factories with Artificial Lighting (PFALs): A New Paradigm for Edible Flower Production

3.1. Overview of PFALs: Principles and Components

The latest advancement in edible flower cultivation is controlled-environment agriculture, particularly PFALs. PFALs are advanced indoor growing systems designed to produce crops consistently and efficiently, regardless of weather or climate conditions. These systems typically include insulated and airtight structures, multi-layer vertical growing shelves, and fully automated controls for environmental factors [32]. Key parameters such as light spectrum and intensity, photoperiod, temperature, humidity, CO₂ concentration, and nutrient delivery can be carefully adjusted to optimize plant growth and quality. Compared to traditional outdoor farming, PFALs can achieve crop growth that is two to four times faster [33] and can significantly improve resource use efficiency [34]. They also use water, CO₂, and light more effectively than greenhouses [32]. However, ongoing improvements are still needed to further enhance energy efficiency and sustainability [35].

3.2. Advantages of PFALs for Edible Flowers

PFALs offer several key advantages for growing high-value crops like edible flowers. By fully controlling the environment, PFALs enable year-round flower production, ensuring a stable and reliable supply to meet market demand. This level of control is especially important for edible flowers, which are highly sensitive to changes in temperature, light, and humidity that can influence their color, fragrance, flavor, and nutritional content. Additionally, PFALs operate as closed systems, allowing for pesticide-free production and reducing concerns about chemical residues [36]—an essential factor for flowers that are consumed directly. The economic feasibility of PFALs has already been proven for certain crops, such as lettuce [37], and similar principles can be applied to edible flowers, particularly those aimed at premium and functional food markets.

In terms of quality, PFALs offer excellent control over the light spectrum, intensity, and photoperiod—factors that strongly influence the production of important secondary metabolites such as flavonoids, phenolics, and carotenoids [38]. These compounds contribute to the visual appearance, flavor, aroma, and health benefits of edible flowers. Adjusting light conditions, such as the balance between red, blue, and far-red light, can enhance flower color and promote the development of desired qualities. Moreover, maintaining optimal temperature and humidity inside PFALs helps ensure uniform flower size, shape, and shelf life while reducing the risk of damage and postharvest losses.

3.3. Current Status of Edible Flower Research in PFALs

Although PFALs offer great potential for edible flower production, research in this area is still limited. Only a few species have been systematically studied in PFAL systems. For example, it has been reported that prolonged photoperiod can increase calendula yield, secondary metabolites content, and DPPH scavenging activity [39]. Changes in light spectrum, such as the use of R and FR lighting, can regulate the flowering of calendula [40]. In nasturtium, the EC of 1.0 dS m⁻¹ is reported as the optimal condition for cutting seedlings grown in PFALs [41]. The nasturtium yield cultivated under 24-h lighting in PFALs increases as DLI rises from 17.3 to 34.6 mol m⁻² d⁻¹ without causing physiological stress to the plants [42]. Several French marigold (Tagetes patula) cultivars, including ‘Bee’, ‘Bolero’, ‘Gold’, ‘Red’, ‘Tangerine’, and ‘Yellow’, were cultivated in PFAL and showed that ‘Red’ cultivar had the highest number of harvested flowers, and the fresh and dry weights of flowers, which is the suitable candidate to produce in PFAL [43]. An 8-h photoperiod induced floral differentiation in French marigold grown in PFALs; however, a longer period was required for flower bud development, and plant growth was significantly reduced compared to photoperiods of 12 or 16 h [44].

These findings highlight the crucial role of environmental parameters, particularly light, temperature, and nutrient supply, in determining growth, flowering behavior, and quality in edible flowers grown under PFAL conditions, thereby underscoring the need for a deeper understanding of these factors.

4. Key Environmental Factors Influencing Plant Growth and Flowering

A complex interplay of environmental factors regulates plant growth and flowering. Light, temperature, and nutrient solution are key environmental factors that can be precisely controlled in PFALs, directly influencing plant growth, flowering, and quality. Understanding how they influence plant growth allows for the development of more efficient cultivation strategies. The following sections highlight the role of light, temperature, and nutrient solution as key factors in regulating plant growth and flowering (Table 2). As research on edible flowers in PFALs is still limited, examples in the following sections may also include other plant species and cultivation systems to illustrate fundamental principles applicable to edible flower production in PFALs.

4.1. Light

Plant growth and development are influenced by various environmental factors, with light playing a particularly important role. Light is crucial for photosynthesis and plant growth. The effects of light on plant growth and development are complex. In addition to photosynthesis, flowering time and morphogenesis are also regulated by light. Three light properties influence plant growth and development, including light intensity, photoperiod, and light quality or spectrum.

Light intensity refers to the amount of light that spreads over a given area. The measurement of how much light a plant receives differs from human light perception. Since the wavelength range of light suitable for plant photosynthesis is between 400 and 700 nm, regarded as photosynthetically active radiation (PAR), the light intensity that plants receive is measured by the number of photons flux density in this range, called photosynthetic photon flux density (PPFD) [45]. Light intensities between 720 and 856 µmol m⁻² s⁻¹ have been reported to promote the growth of species such as Anthurium sp., Zantedeschia aethiopica, and Spathiphyllum wallisii under constructed wetland conditions [46]. Light intensity also significantly affects leaf morphology. In Passiflora morifolia, Passiflora palmeri var. sublanceolata, and Passiflora suberosa subsp. litoralis, the largest and specific leaf areas were recorded under 75% shade, whereas thicker leaves were observed under full sunlight and 25% shade [47]. Moreover, floral pigmentation is strongly influenced by light. Tuberose, boronia, and peony flowers exhibit reduced pigmentation when grown under shaded conditions. This effect is associated with the downregulation of PAL and CHS genes, key enzymes in the anthocyanin biosynthesis pathway in peony. Conversely, full sunlight enhances reddish-purple coloration in these flowers [48,49]. When plants were cultivated under the light intensity of 180 µmol m⁻² s⁻¹, the photoinhibition symptoms, such as chlorosis, necrosis, and stunted growth, were found [50].

Photoperiod is the light signal for many living things, including plants. Photoperiod is related to the day length and circadian clock, which leads plants to adapt to environmental change throughout the year by using light as an indicator [51]. Flowering is the photoperiodic response, and plants can be classified as day-neutral, short-day (SD), and long-day (LD) based on their flowering behavior. Torabi et al. investigated the photoperiodic response of four cultivars of Carthamus tinctorius and reported that, when grown under photoperiods of approximately 12–15 h day⁻¹, three cultivars exhibited an inverse relationship between photoperiod length and days to flowering; flowering occurred earlier under longer photoperiods (up to 15 h day⁻¹) [52]. Moreover, in photoperiod-sensitive plants, nighttime lighting is often used to manipulate flowering responses. For example, applying low light intensity at night promotes flowering in LD plants but inhibits flowering and encourages vegetative growth in SD plants. In chrysanthemum, an SD plant that requires long dark periods for floral initiation, end-of-day low-intensity lighting extends the photoperiod and regulates flowering [53]. It has been widely reported that night interruption lighting (NIL) can promote flowers. Furthermore, the light spectrum used for NIL and the position of leaves receiving the light also play important roles in regulating flowering. White (W), blue (B), and far-red (FR) light have been studied as NIL and were found to promote flowering in chrysanthemum, whereas red (R) light showed no significant effect [54,55].

The spectrum exhibits different light colors, such as rainbow colors that humans can sense. Plants can perceive light further than visible light, including ultraviolet (UV) and FR wavelengths. Since lighting technology has advanced, customized LEDs have become available for research and have been applied to PFALs. The application of R and B light generally increases yield in most plant species; nevertheless, the optimum R: B ratio depends on the species and cultivars. Green (G) light has a higher penetrating ability to the leaf and is absorbed by photosynthetic pigment less than R and B light, thereby allowing G light to enter deeper into the leaf tissue [56]. UV light enhances the phenolic compounds, essential oils, and antioxidant capacities of herbs compared to white light [57]. In contrast, FR light is more easily transmitted through a plant canopy and signals plants growing under the canopy to respond to the shade, called shade avoidance, by stem elongation and leaf expansion [58]. Moreover, FR also plays a regulatory role in the flowering of some herbaceous plants. A lack of FR can inhibit flower initiation or development in some long-day species, including Campanula carpatica and tickseed (Coreopsis × grandiflora) [59], whereas a high R: FR ratio, as a night interruption, can accelerate flowering in certain short-day species [60].

Not only the light intensity and photoperiod individually affect plant growth and development, but their combined effect—quantified as the daily light integral (DLI)—also regulates these processes. DLI represents the total amount of light, measured as photosynthetic photon flux, that a plant receives per day. Adjusting either light intensity or photoperiod can modify the DLI, allowing growers to optimize plant growth and flowering in controlled environments. In PFALs, where lighting can be fully controlled, several lighting strategies can be created and applied to the cultivation system. According to previous studies, DLI significantly affects flowering responses in many ornamental species. For example, tickseed, echinacea (Echinacea × hybrida), lavender (Lavandula angustifolia), and lobelia (Lobelia × speciosa) exhibited reduced flowering percentages under low DLI conditions compared to high DLI [61]. In contrast, geranium and petunia (Petunia × hybrida) showed earlier flowering under moderate to high DLI levels than under low DLI conditions [62]. In addition, using supplemental LED light when growing Viola cornuta under greenhouse conditions in winter helps increase the number of flowers per plant [63,64]. Supplemental lighting enhances light availability, leading to higher flower fresh weight and promoting the accumulation of secondary compounds, such as total flavonoid glycosides and total phenolic content, in flowers of V. cornuta [64].

Overall, light is a multifaceted environmental factor that regulates photosynthesis, vegetative growth, flowering, and morphological traits in plants. Through the precise control of light intensity, photoperiod, spectrum, and daily light integral (DLI), PFAL systems offer significant opportunities to optimize the growth and flowering of ornamental and edible flowers.

4.2. Temperature

Temperature is a critical environmental factor influencing both the growth and flowering of plants in general, and of edible flowers in particular, affecting not only the timing of flowering but also flower size, quality, and reproductive success. Temperature acts as both a trigger and a regulator for the timing of flowering in edible flowers, with deviations from optimal conditions leading to delays, premature blooming, or compromised flower quality. Many plants require specific temperature ranges to initiate flowering; high temperatures can accelerate flowering, whereas low temperatures may delay it or induce dormancy. For instance, increasing the temperature from 18 °C to 24 °C reduced the time to flowering by 20% to 40% in hibiscus (Hibiscus rosa-sinensis), miniature roses (Rosa sp.), sinningia (Sinningia speciosa), gerbera (Gerbera × hybrida), kalanchoe (Kalanchoe blossfeldiana), hydrangea (Hydrangea macrophylla), begonia (Begonia × hiemalis), calceolaria (Calceolaria uniflora), and pelargonium (Pelargonium domesticum) grown at intermediate light intensity [65]. A similar trend was observed in nasturtium cv. ‘Empress of India’, where the fastest flowering occurred at 25 °C (41 days), was slightly delayed at 30 °C (45 days), and was greatly delayed at 10 °C (91 days) [66].

Optimal temperature conditions not only accelerate the onset of flowering but also enhance both floral quantity and yield. In chrysanthemum cv. ‘Taiwan Hangju No. 1’, the highest and most synchronized flowering was observed at 25/20 °C, resulting in 2049 flowers and a dry weight yield of 281.8 g within a concentrated harvest period. In contrast, elevated temperatures (30/25 °C and 35/30 °C) produced very few or no flowers, while lower temperatures (15/13 °C and 20/15 °C) resulted in reduced flower numbers and a protracted, less synchronized harvest period [67].

Excessive heat can stress plants, sometimes delay flowering, or cause poor-quality blooms. High temperatures may cause flowers to wither, drop prematurely, or fail to open fully. The visible bud stage is particularly sensitive to high-temperature stress in garden rose cultivars such as ‘Belinda’s Dream’ (BD) and ‘RADrazz’ (KO); exposure to two weeks of high temperatures (36/28 °C day/night) during this stage drastically reduced flower size and increased the likelihood of flower abscission, especially in the more sensitive BD cultivar [68]. Pansies, which are edible flowers valued for their vibrant blooms, also exhibit reduced growth and flowering at high temperatures (above 30 °C), limiting their use during hot periods. Research has shown that, at 30 °C, all 12 pansy cultivars studied exhibited a 20–77% reduction in flower bud number and a 14–44% reduction in flower diameter, with the overall color display dropping by 60–88% [69].

Elevated temperatures generally accelerate flower bud development, leading to earlier blooming, particularly in annuals and certain tropical species that respond to sustained warmth by hastening their flowering process. However, if temperatures increase too rapidly or prematurely within the season, plants may experience precocious flowering, which can shorten the bloom period and result in less robust flowers. Inamoto et al. [70] reported strong positive correlations between temperature and both flowering cycles and flower number in three cut rose varieties; higher temperatures accelerated flowering cycles and increased flower numbers but tended to reduce individual flower weight and fullness.

Moreover, temperature fluctuations, particularly cooler nocturnal periods, can significantly affect flower quality and the accumulation of secondary metabolites. Both day and night temperatures are critical: elevated daytime temperatures enhance metabolic activity, while reduced nighttime temperatures facilitate physiological recovery and, in certain species, can serve as a cue for floral initiation [71,72,73]. For example, elevated constant temperatures (25 °C) accelerate flowering and increase the number of flower heads in chamomile (Matricaria chamomilla) but result in reduced flower head size and lower total dry weight. In contrast, cultivating chamomile with a daytime temperature of 25 °C and a lower nighttime temperature of 15 °C produces larger flower heads, greater total dry weight, higher essential oil yield per plant, and increased chamazulene content in the oil [74].

In summary, growing temperature has a pronounced effect on flowering, yield, and crop quality, making temperature management a critical aspect of cultivation. This is particularly important for the production of edible flowers in greenhouse systems or plant factories, where precise temperature control can be implemented to optimize both yield and quality of the target flowers.

4.3. Nutrient Solution

In addition to light, nutrient availability is one of the most influential environmental factors affecting plant growth and development. In soil-based cultivation, nutrients are absorbed from the soil. However, in soilless systems such as hydroponics and PFALs, all essential mineral elements must be supplied through a nutrient solution. This makes nutrient management a central component in controlled-environment agriculture, where precise nutrient composition and concentration regulation can significantly impact plant physiology and productivity.

A nutrient solution typically comprises macronutrients—including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S)—and micronutrients such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), and molybdenum (Mo) [75]. Each element plays a specific role in plant metabolic processes. For instance, nitrogen is vital for chlorophyll production and protein synthesis [76]; phosphorus is involved in energy transfer [77]; and potassium regulates water balance and enzyme activation [78]. A balanced nutrient solution ensures that these physiological functions proceed optimally, supporting vegetative growth, flower development, and overall yield.

Electrical conductivity (EC) is often used to estimate the total ionic concentration of a nutrient solution and serves as an indirect indicator of nutrient strength. Flower production in begonia was maximized at a fertilizer EC of 1.6 dS m⁻¹, with both lower and higher EC levels reducing inflorescence number [79]. Likewise, in calendula, a nutrient solution EC of 1.5 dS m⁻¹ combined with foliar application of 0.5 µM brassinosteroid produced the highest flower numbers, while increasing EC to 4.5 dS m⁻¹ reduced flowering but enhanced secondary metabolites such as alpha-cadinol, delta-cadinene, sigma-cadinene, and flavonoids [80]. Increasing EC levels enhanced flavonoid content, antioxidant capacity and mineral accumulation in verbena, whereas in geranium, they decreased the total phenolic and total flavonoid contents and antioxidant capacity [81]. Similarly, growing Viola under increasing EC levels improved growth, including leaf area, shoot number, and plant volume, and also the number of inflorescences. The EC of 5 mS cm⁻¹ was identified as the optimal level; higher EC levels beyond this point negatively impacted plant performance [82].

These findings highlight the importance of precise EC management. The EC sensor indicates total nutrient concentration but does not reflect the specific uptake of individual nutrients by plants. Since nutrient uptake varies with transpiration, fluctuations in nutrient concentrations within the root zone can occur. Consequently, using recycled nutrient solutions in closed-loop systems may lead to nutrient imbalances and potential yield reduction [83]. While an adequate EC level supports healthy plant growth, excessively high concentrations can cause osmotic stress, reduced water uptake, and nutrient imbalances. Conversely, insufficient EC may result in nutrient deficiencies, stunted growth, and delayed flowering. Thus, continuous monitoring and precise adjustment of EC are critical for maintaining optimal nutrient availability throughout the crop cycle.

Flowering is a key determinant of yield and market quality in edible flower production. N is an important factor influencing flowering behavior among various environmental and nutritional factors. Plants absorb N primarily in two forms: nitrate (NO₃⁻) and ammonium (NH₄⁺), and the ratio between these two forms can significantly influence not only vegetative growth but also reproductive development [84]. Nitrate availability exhibits a U-shaped effect on flowering in Arabidopsis sp., with optimal concentrations promoting flowering, while both lower and higher levels cause delays [85]. Apart from nitrogen, other nutrient elements such as P and K also influence reproductive processes. Elevated P concentrations enhanced both vegetative growth and flowering in New Guinea impatiens (Impatiens hawkeri), as reflected by increased plant height and diameter, and improved flowering [86]. In begonia, adequate phosphorus supply is essential for optimal flowering; supplying 50 to 100 mg L⁻¹ P in the fertigation solution significantly increased the number of inflorescences compared to no phosphorus, while plants without phosphorus were visibly smaller and produced fewer flowers [87]. In contrast, for calendula grown hydroponically, the greatest number of flower buds and capitula was achieved with an extra-low phosphorus supply of 5 mg L⁻¹ combined with intermittent watering; higher phosphorus levels increased leaf biomass but proportionally reduced flower production, indicating that lower P supply favors reproductive growth in this medicinal plant [88]. The level of P significantly affected the number of florets per spike in Gladiolus sp. [89]. In roses, increasing monopotassium phosphate (KH₂PO₄) concentrations up to 3.0 g L⁻¹ significantly enhanced flower diameter, whereas higher concentrations (4.0–5.0 g·L⁻¹) led to a reduction [90]. The potassium chloride (KCl) application can improve sunflower quality, such as flower stem and capitulum development [91]. Targeted nutrient management, particularly with higher potassium levels, can effectively promote growth and flowering in Dianthus (Dianthus chinensis). High potassium fertilization (43% K) resulted in the highest leaf count, fresh and dry weight, as well as the greatest flower production [92]. These observations suggest that manipulating the levels and forms of key macronutrients can markedly influence flowering responses in various species. Further research on nutrient optimization holds strong potential for enhancing edible flower production in PFAL systems, where precise control of nutrient supply can be fully leveraged.

Table 2. Effects of light, temperature, and nutrient solution on flower production.

Environmental Factors		Plant Species	Effect on Flower Production	Citations
Light	Shaded condition	Boronia heterophylla, Paeonia lactiflora	Reducing floral pigmentation	Lee et al., 2007 [48] Zhao et al., 2012 [49]
	Photoperiod	Carthamus tinctorius	Flowering occurred earlier under longer photoperiods (up to 15 h day−1)	Torabi et al., 2020 [52]
	Night interruption lighting	Chrysanthemum	End-of-day low-intensity lighting extends the photoperiod and regulates flowering	Trivellini et al., 2023 [53]
	Night interruption lighting with white, blue, or far-red light	Chrysanthemum	Promote flowering	Park and Jeong, 2019 [54] Park and Jeong, 2019 [55]
	Far-red light	Campanula carpatica, tickseed	Lack of FR can inhibit flower initiation or development	Runkle and Heins, 2001 [59]
	Daily light integral	Tickseed, Echinacea × hybrida, Lavander, Lobelia × speciosa	Reduced flowering percentages and inflorescence/bud number under low DLI conditions compared to high DLI	Whitman et al., 2022 [61]
		Pelargonium × hortorum, Petunia	Earlier flowering under moderate to high DLI levels than under low DLI conditions	Chaudhary and Poudyal, 2025 [62]
		Viola cornuta	Using supplemental LED light when growing Viola cornuta L. helps increase the number of flowers per plant, flower fresh weight and promotes the accumulation of secondary compounds	Koksal et al., 2015 [63] Locatelli et al., 2024 [64]
Temperature		hibiscus, miniature roses, sinningia, gerbera, kalanchoe, hydrangea, begonia, calceolaria, and pelargonium	Increasing the temperature from 18 °C to 24 °C reduced the time to flowering by 20% to 40%	Mortensen, 2014 [65]
		Nasturtium	The fastest flowering occurred at 25 °C (41 days), was slightly delayed at 30 °C (45 days), and was greatly delayed at 10 °C (91 days)	Munir et al., 2015 [66]
		Chrysanthemum	At 25/20 °C, flowering was highest and most synchronized (2049 flowers, 281.8 g dry weight), while higher or lower temperatures reduced flower number and harvest uniformity	Nakano et al., 2020 [67]
		Rose cv. ‘Belinda’s Dream Knock Outrose ‘RADrazz’	Exposure to two weeks of high temperatures (36/28 °C day/night) during visible bud stage drastically reduced flower size and increased the likelihood of flower abscission	Greyvenstein et al., 2014 [68]
		Pansy	All 12 pansy cultivars were grown at 30 °C exhibited a 20–77% reduction in flower bud number and a 14–44% reduction in flower diameter, with the overall color display dropping by 60–88%	Warner and Erwin, 2006 [69]
		Chamomile	Chamomile grown at 25/15 °C (day/night) produces larger inflorescences, greater biomass, higher essential oil yield, and elevated chamazulene content	Saleh, 1970 [74]
Nutrient solution		Begonia	Flower production was maximized at a fertilizer EC of 1.6 dS m−1, with both lower and higher EC levels reducing inflorescence number	James and van Iersel, [79]
		Calendula	1.5 dS m−1 EC plus 0.5 µM brassinosteroid yielded the most flowers, while 4.5 dS m−1 reduced flowering but boosted alpha-cadinol, delta-/sigma-cadinene, and flavonoids	Mokhtari and Afshari, 2016 [80]
		Pansy	Flower number peaked at 5 dS m−1 EC across all color variants, but declined at 6.5 dS m−1	Kentelky et al., 2022 [82]
		Begonia	Supplying 50–100 mg L−1 P increased inflorescences compared to no P, as P-deficient plants were smaller and produced fewer flowers	James and van Iersel, 2001 [87]
		Calendula	An extra-low P supply (5 mg L−1) with intermittent watering maximized buds and capitula, while higher P increased leaf biomass but reduced flowering	Stewart and Lovett-Doust, 2003 [88]
		Rose	Increasing KH2PO4 to 3.0 g L−1 enhanced flower diameter, but 4.0–5.0 g L−1 reduced it	Ma et al., 2021 [90]

Table 2. Effects of light, temperature, and nutrient solution on flower production.

Environmental Factors		Plant Species	Effect on Flower Production	Citations
Light	Shaded condition	Boronia heterophylla, Paeonia lactiflora	Reducing floral pigmentation	Lee et al., 2007 [48] Zhao et al., 2012 [49]
	Photoperiod	Carthamus tinctorius	Flowering occurred earlier under longer photoperiods (up to 15 h day−1)	Torabi et al., 2020 [52]
	Night interruption lighting	Chrysanthemum	End-of-day low-intensity lighting extends the photoperiod and regulates flowering	Trivellini et al., 2023 [53]
	Night interruption lighting with white, blue, or far-red light	Chrysanthemum	Promote flowering	Park and Jeong, 2019 [54] Park and Jeong, 2019 [55]
	Far-red light	Campanula carpatica, tickseed	Lack of FR can inhibit flower initiation or development	Runkle and Heins, 2001 [59]
	Daily light integral	Tickseed, Echinacea × hybrida, Lavander, Lobelia × speciosa	Reduced flowering percentages and inflorescence/bud number under low DLI conditions compared to high DLI	Whitman et al., 2022 [61]
		Pelargonium × hortorum, Petunia	Earlier flowering under moderate to high DLI levels than under low DLI conditions	Chaudhary and Poudyal, 2025 [62]
		Viola cornuta	Using supplemental LED light when growing Viola cornuta L. helps increase the number of flowers per plant, flower fresh weight and promotes the accumulation of secondary compounds	Koksal et al., 2015 [63] Locatelli et al., 2024 [64]
Temperature		hibiscus, miniature roses, sinningia, gerbera, kalanchoe, hydrangea, begonia, calceolaria, and pelargonium	Increasing the temperature from 18 °C to 24 °C reduced the time to flowering by 20% to 40%	Mortensen, 2014 [65]
		Nasturtium	The fastest flowering occurred at 25 °C (41 days), was slightly delayed at 30 °C (45 days), and was greatly delayed at 10 °C (91 days)	Munir et al., 2015 [66]
		Chrysanthemum	At 25/20 °C, flowering was highest and most synchronized (2049 flowers, 281.8 g dry weight), while higher or lower temperatures reduced flower number and harvest uniformity	Nakano et al., 2020 [67]
		Rose cv. ‘Belinda’s Dream Knock Outrose ‘RADrazz’	Exposure to two weeks of high temperatures (36/28 °C day/night) during visible bud stage drastically reduced flower size and increased the likelihood of flower abscission	Greyvenstein et al., 2014 [68]
		Pansy	All 12 pansy cultivars were grown at 30 °C exhibited a 20–77% reduction in flower bud number and a 14–44% reduction in flower diameter, with the overall color display dropping by 60–88%	Warner and Erwin, 2006 [69]
		Chamomile	Chamomile grown at 25/15 °C (day/night) produces larger inflorescences, greater biomass, higher essential oil yield, and elevated chamazulene content	Saleh, 1970 [74]
Nutrient solution		Begonia	Flower production was maximized at a fertilizer EC of 1.6 dS m−1, with both lower and higher EC levels reducing inflorescence number	James and van Iersel, [79]
		Calendula	1.5 dS m−1 EC plus 0.5 µM brassinosteroid yielded the most flowers, while 4.5 dS m−1 reduced flowering but boosted alpha-cadinol, delta-/sigma-cadinene, and flavonoids	Mokhtari and Afshari, 2016 [80]
		Pansy	Flower number peaked at 5 dS m−1 EC across all color variants, but declined at 6.5 dS m−1	Kentelky et al., 2022 [82]
		Begonia	Supplying 50–100 mg L−1 P increased inflorescences compared to no P, as P-deficient plants were smaller and produced fewer flowers	James and van Iersel, 2001 [87]
		Calendula	An extra-low P supply (5 mg L−1) with intermittent watering maximized buds and capitula, while higher P increased leaf biomass but reduced flowering	Stewart and Lovett-Doust, 2003 [88]
		Rose	Increasing KH2PO4 to 3.0 g L−1 enhanced flower diameter, but 4.0–5.0 g L−1 reduced it	Ma et al., 2021 [90]

Beyond environmental control and nutrient management, several emerging interventions show practical promise for edible flower production. Biostimulants, such as protein hydrolysates, increased plant and flower biomass and flower number in calendula while reshaping the floral metabolome, indicating potential to steer quality traits via targeted dosing and timing of the biostimulants [93]. In pansy, the application of biostimulant improved seedling growth and quality parameters [94], supporting its use to accelerate uniform transplant production. The application of beneficial microorganisms to plant production also looks promising. The application of Trichoderma spp. to the plant root zone enhanced growth, flowering, and nutrient status in nasturtium [95], suggesting microbial inoculants could be complemented to PFAL fertigation regimes. In addition, combined selenium (Se) and silicon (Si) applications alleviated short-term drought stress in French marigold [96]; thus, such biofortification can be used for stress mitigation and quality enhancement. Collectively, these tools can be integrated with PFALs to fine-tune quality (color, aroma, bioactive compound), improve resource-use efficiency, and support scalable, commercially viable edible flower production.

5. Challenges, Research Gaps, and Future Directions

While PFALs offer great potential for improving edible flower production, several challenges and gaps in knowledge must be addressed. Current research on growing edible flowers in PFALs is still in its early stages, and many technical and economic questions remain. One major challenge is the high operating cost of PFALs. Energy use—especially for artificial lighting, temperature control, and air movement—is a key concern. Although new LED technologies have made lighting more efficient, electricity costs are still high [35]. This can be a barrier for the commercial production of edible flowers, which often target niche markets. More research is needed to develop lighting strategies (for example, choosing the best light spectrum, duration, and intensity) to lower energy use while maintaining good yield and quality. In addition, integrating renewable energy sources such as solar, wind, or biomass into PFALs operations could help offset electricity costs and improve the overall sustainability of production systems [97].

Different species and cultivars of edible flowers respond differently to environmental factors, such as light, temperature, and nutrients. However, most current optimal conditions for cultivation in PFALs have been developed for leafy greens [98,99,100], and their suitability for edible flowers is still uncertain. Most commercially important edible flower species, such as viola, pansy, dianthus, rose, begonia, and borage, have not yet been studied in PFAL systems. Little is known about how different light conditions, temperature, nutrient formulations, or other environmental factors affect these species in controlled environments. Future research should also explore how PFALs technologies, such as dynamic lighting strategies and precision nutrient management, can enhance specific traits, such as flower color, aroma, taste, shelf life, and health-promoting compounds.

While commercial-scale PFAL cultivation is currently concentrated on crops such as lettuce, edible flower production remains largely at the experimental stage with limited progress toward scaling up to commercial implementation. Therefore, further research is needed to develop scalable production systems and protocols that can enable the successful transition of edible flowers from experimental to commercial PFAL operations. More studies are needed on production costs and market potential to determine which edible flower species can be grown profitably in PFALs. Selecting species with high market value and strong demand will be important for future commercial success. Many of the health benefits of edible flowers come from secondary metabolites such as flavonoids, phenolics, and essential oils. However, little is known about how environmental factors in PFALs—such as light, temperature, and nutrient supply—affect the production of these compounds. Advanced biotechnology, such as metabolomics and transcriptomics, can help researchers understand how to improve flower quality in controlled environments (

Table 3. Examples of how advanced biotechnological tools can be applied to improve the quality of edible flowers.

Plant Species	Research Focus	Main Findings	Application for Edible Flowers in PFALs
Cosmos bipinnatus	Flower color—flavonoid biosynthesis, transcription factors (MYB, bHLH)	Identified key metabolites and regulatory genes controlling anthocyanin accumulation in different flower colors [102].	Guide lighting and nutrient strategies to enhance desired flower colors.
Camellia huana	Flower color and aroma—carotenoid biosynthesis	Revealed genes and metabolic pathways responsible for pigmentation and fragrance formation [103].	Develop protocols to improve visual and sensory qualities.
Gloriosa spp.	Flower color—anthocyanin accumulation, MYB genes	Linked MYB gene expression with anthocyanin content in tepals [104].	Enable precise environmental control to intensify pigmentation.
Hemerocallis citrina	Flower development, metabolites, dynamics, differentially expressed genes (DEGs)	Showed stage-specific metabolite accumulation and gene expression during flowering [105].	Optimize harvest timing for peak nutritional and sensory quality.

). In addition, integration with nonbiological technology, such as AI-based software, could improve electricity use efficiency and reduce greenhouse gas emissions [101], thereby enhancing the sustainability and economic viability of edible flower production in PFALs.

Finally, consumer acceptance is an important factor. Although interest in high-quality, pesticide-free edible flowers is growing, more studies are needed on consumer preferences, sensory qualities, and willingness to pay for PFAL-grown products. Building consumer trust and awareness will be key to expanding the market. Addressing these challenges will require teamwork across different fields, including plant science, horticulture, engineering, and market research. Progress in these areas will help make PFALs a more sustainable and profitable system for producing high-value edible flowers.

6. Conclusions

The global market for edible flowers is growing, driven by increasing consumer demand for attractive, functional, and safe food products. However, conventional cultivation systems, such as open-field and greenhouse production, face limitations in ensuring consistent yield and quality due to environmental variability. PFALs offer a promising solution by enabling year-round production, improving yield and quality through precise control of light, temperature, and nutrients, and supporting pesticide-free cultivation. Recent studies on a few species, including calendula, nasturtium, and African marigold, have demonstrated the potential of PFALs to enhance both yield and the accumulation of secondary metabolites in edible flowers. Nonetheless, many commercially important species remain unexplored, and further research is needed to optimize cultivation protocols, improve energy efficiency, and ensure economic viability. Future research should also focus on consumer acceptance, sensory qualities, and market development to support the broader adoption of PFAL-grown edible flowers.