Greenhouse Update

Welcome to UMass Extension’s Greenhouse Update for commercial growers of greenhouse crops and flowers.

Tina Smith, former University of Massachusetts Extension Floriculture Specialist and Leanne Pundt, University of Connecticut Extension started the New England Greenhouse Update website in 2005. The website was a collaborative effort to contribute pest messages, photos and other information from observations at greenhouses in Massachusetts and Connecticut.

As of the 2018 growing season, UMass Extension's Greenhouse Crops & Floriculture Team will use this web site to post messages for Massachusetts growers covering timely topics and updates based on scouting observations.  If you have changed your email address or if you are not receiving our email messages, please visit our E-Mail List page to subscribe.

Leanne Pundt has an email list specifically for Connecticut growers. If you are greenhouse grower located in Connecticut and are not currently receiving specific email updates from Leanne Pundt, UConn Extension, please send your email to leanne[dot]pundt[at]uconn[dot]edu and she will add you to her list.

The University of Massachusetts Greenhouse Crops and Floriculture Program supports the greenhouse industry with researched based information on environmentally safe production practices. Educational activities include newsletters, publications, workshops, conferences, training programs, diagnostic services and research.

Latest Greenhouse Update

  • Greenhouse Updates: May 7, 2025

    Caring for Plants in Retail Areas

    With spring fully here, plants are being moved from production greenhouses to retail areas, or they’re being received from vendors and moved to retail areas. One of the most important steps in maintaining plant quality is receiving them properly. Immediately after receiving plants, open cases to let out any heat that may have built up during transit and inspect carefully for pests, diseases or damage. Water to help settle the plants and the substrate in the pots before display. Be sure to water plants thoroughly; do not just wet the top of the soil. Display plants as soon as possible and take measures to avoid bruising leaves and flowers or damaging stems and flower buds from moving and handling.

    Plant display in a retail greenhouse (G. Njue)
    Plant display in a retail lath house (G. Njue)

    We always hope for quick turnover in the retail area, but some plants stay in retail areas for prolonged periods of time. To maintain optimum plant for plants on display, give attention to the following:

    1. Watering - Plants in retail areas require regular, gentle watering to maintain high quality. Too little or too much watering can have a detrimental effect. Inspect plants regularly early in the morning and early afternoon and water/irrigate as needed. If possible, group plants by watering requirements. Always watch the weather forecast. If cloudy, rainy weather is expected, reduce watering to avoid overwatering the plants. Overwatered plants can be prone to root diseases.

    2. Fertility - To keep plants in retail areas looking good, continue to provide adequate nutrition. Regularly inspect plants for nutrient deficiency symptoms and fertilize as needed. The most common nutrient deficiency of plants in retail settings are nitrogen deficiency, phosphorus deficiency and pH induced iron deficiency or toxicity symptoms. 

    Nitrogen deficiency shows up as lower leaf yellowing. In most cases nitrogen deficiency happens in response to plants not being fertilized enough. However, improper watering can also cause nutrient deficiency. Installing a fertilizer injector can help prevent nitrogen deficiency.

    Phosphorus deficiency usually shows up as reddening or purpling of lower leaves. In many cases, phosphorus deficiency symptoms are not caused by lack of phosphorus, but a lack of phosphorus uptake by the plants. This is more common early in the season when temperatures are cool and plants are placed outside. Plants growing in cold soil have more difficulty taking up phosphorus. Adding phosphorus will not fix the problem, but moving plants into a heated space will. Adding phosphorus under these circumstances may cause plants to stretch when temperatures warm up.

    Lower leaf purpling in pansy caused by phosphorus deficiency (G. Njue)

    pH-induced nutrient problems. Some nutrient elements are more or less available based on substrate pH. Petunia, calibrachoa and other iron inefficient plants exhibit iron deficiency when substrate pH goes above 6.2. On the other hand, geranium and other iron efficient plants exhibit iron toxicity when substrate pH goes below 6.2. Using a neutral fertilizer that is neither potentially acidic or potentially basic is the ideal way of managing ph-related nutrient problems in a retail setting.

    High pH iron deficiency symptoms on petunia in a retail greenhouse (G. Njue)

    3. Protect plants from pests and diseases -Always inspect incoming plants and conduct monitoring on regular basis. Keep the retail area clean. Regularly remove and discard old, unsightly or diseased plants and other plant debris. Put them in a covered trash can and dispose of them out of the retail area. Plant debris can serve as a reservoir for pest problems. Regularly scout and remove weeds in and around the perimeter of the retail area and discard them; weeds may harbor pests and disease pathogens. If plants were grown using biological pest control, plan to continue deploying biological controls in the retail area.

    4. Keep plants well groomed. Inspect plants at least three times a week and remove all brown or yellowing leaves, dead leaves or broken stems. Remove plants that are looking old, dead or dying, and replace them with new plants. This will keep plants looking fresh and of high quality on the display.

    For more information check out the following links:

    - Geoffrey Njue, Extension Specialist, UMass Extension Greenhouse Crops and Floriculture Program

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