Next Article in Journal
Assessing Quantitative Criteria for Characterization of Quality Categories for Grafted Watermelon Seedlings
Previous Article in Journal
Effects of Biochar on Container Substrate Properties and Growth of Plants—A Review
Previous Article in Special Issue
Water-Related Variables for Predicting Yield of Apple under Deficit Irrigation
Open AccessArticle

Timing of a Short-Term Reduction in Temperature and Irradiance Affects Growth and Flowering of Four Annual Bedding Plants

United States Department of Agriculture, Agricultural Research Service, Application Technology Research Unit, Wooster, OH 44691, USA
Author to whom correspondence should be addressed.
Horticulturae 2019, 5(1), 15;
Received: 7 December 2018 / Accepted: 23 January 2019 / Published: 1 February 2019
(This article belongs to the Special Issue Abiotic Stress Effects on Performance of Horticultural Crops)
PDF [262 KB, uploaded 25 February 2019]


Heating and supplemental lighting are often provided during spring greenhouse production of bedding plants, but energy inputs are a major production cost. Different energy-savings strategies can be utilized, but effects on plant growth and flowering must be considered. We evaluated the impact and timing of a two-week low-energy (reduced temperature and irradiance) interval on flowering and growth of impatiens (Impatiens walleriana Hook.f. ‘Accent Orange’), pansy (Viola × wittrockiana Gams. ‘Delta Premium Blue Blotch’), petunia (Petunia × hybrida Hort. Vilm.-Andr. ‘Dreams Pink’), and snapdragon (Antirrhinum majus L. ‘Montego Violet’). Flowering was delayed 7 to 10 days when the low-energy exposure occurred before flowering. Flower number was reduced 40–61% in impatiens, 33–35% in petunia (low-energy weeks 5–6 and weeks 7–8, respectively), and 35% in pansy (weeks 5–6). Petunia and impatiens dry mass gradually decreased as the low-energy exposure occurred later in production; petunias were 26% (weeks 5–6) and 33% (weeks 7–8) smaller, and impatiens were 20% to 31% smaller than ambient plants. Estimated energy savings were 14% to 16% for the eight-week period, but only up to 7% from transplant to flowering. Growers can consider including a two-week reduction in temperature and irradiance to reduce energy, provided an additional week of production is scheduled. View Full-Text
Keywords: temperature; irradiance; ornamental plants; greenhouse production temperature; irradiance; ornamental plants; greenhouse production
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Boldt, J.K.; Altland, J.E. Timing of a Short-Term Reduction in Temperature and Irradiance Affects Growth and Flowering of Four Annual Bedding Plants. Horticulturae 2019, 5, 15.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Horticulturae EISSN 2311-7524 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top