62 articles tagged "Greenhouses & High Tunnels".

Figure 1. Place shadecloth on high tunnels for colored bell pepper production. Photo credit: Ajay Nair

On hot days in the summer, high tunnel growers may wonder whether to place shadecloth on high tunnels. Considering excessive heat inside the structures that may lead to plant stress, blossom drop and unmarketable fruit, there is a rational for doing it. However, it is important to realize the limitations of placing shadecloth on high tunnels in the Midwest. A few years ago, we compared the effect of 30% black shadecloth on temperature and light levels inside a high tunnel. We found shadecloth significantly decreased maximal temperatures for about 10 degrees Fahrenheit while it had no effect on nighttime temperatures.  In terms of light reduction, it ranged from 60% in a sunny day to 30% in a cloudy day. More information about this comparison can be found in the article Temperature and Light Intensity in a High Tunnel Covered with 30% Black Shadecloth in Issue 619. In our experience of[Read More…]


A few weeks ago, Great Lakes Vegetable Producer’s Network discussed hoophouse nutrient management. Judson Reid from Cornell University and David Van Eeckhout from The Good Acre, St. Paul, MN are the invited speakers. They shared their insights in hoophouse nutrient management. I find them very helpful, thus want to pass my notes to Indiana hoophouse growers. Judson pointed two things from greenhouse perspective that may greatly benefit hoophouse growers, one is ventilation, another is pollination. Ventilation is important for managing relative humidity and maintaining carbon dioxide level. But ventilation may be sacrificed in hoophouse for the reason of maintaining temperatures during periods of cool weather. For hoophouse growers, anything that can increase ventilation (end wall vents, peak vent) could greatly benefit vegetable production in the early season. Hoophouse tomato growers can also greatly benefit from bumblebees for pollination. If the structure is usually closed and there is little wind movement[Read More…]


At Southwest Purdue Agriculture Center in Vincennes, IN. We are conducting trials to evaluate annual plasticulture strawberry production systems. Here are the updates of strawberries from different production systems. In a high tunnel, harvest of fall-planted strawberries started in early April. Cultivars Sensation, Radiance, Ruby June were early cultivars; followed by Beauty, Fronteras. So far, Radiance led the yield. Chandler, San Andreas, Camarosa, Liz and Camino Real were relatively later cultivars. In the open field, most cultivars of fall-planted strawberries were in full bloom. As mentioned in the article Strawberry Cold Protection Made a Difference, they are susceptible to frost damage. Cold protection is critical for them at this stage. Row cover was successfully used to protect the flowers from frost damage last week. Day-neutral strawberry cultivars planted on March 9, 2020 established well. Plants were slightly larger under low tunnels. Frost happened last week killed most of the initiated[Read More…]


Thanks to the support from NC-SARE, we are going to continue the study of evaluating grafted cucumbers for early season production in greenhouses and high tunnels by collaborating with farmers in 2020. You can find our 2019 on-farm trials’ summary here:  https://ag.purdue.edu/arge/swpap/Documents/Summary%20of%202019%20On-farm%20Grafted%20Cucumber%20Trials.pdf. The same as in previous years, we are going to supply grafted and normal cucumber transplants for free. These plants were grown in a conventional greenhouse using untreated rootstock seeds. What we want from growers is to grow the same number and variety of grafted and normal cucumber plants, and keep track of the performance of the plants and the yields. We will provide a stipend for your efforts in tracking the data. In addition, we encourage farmers to learn grafting technique and produce grafted plants on your own. We will provide you with technical support and help with the process on-site if it is needed. For more[Read More…]


Figure 1. Powdery mildew on cucumbers grown in a high tunnel.

Powdery mildew is particularly severe in high tunnel and greenhouse growing conditions (Figure 1). It affects a wide range of crops including tomatoes and cucumbers. In addition to using synthetic fungicides to control this disease in high tunnels, we found powdery mildew on cucumbers can also be effectively controlled through variety selection and intensive plant pruning. Cucumber cultivars grown in high tunnels are parthenocarpic. Most of these cultivars are marketed as powdery mildew resistance. However, there are actually a wide range of different levels of resistance existed among parthenocarpic cultivars. In our trials, we found Japanese type cucumbers, especially cultivar Tasty Jade, was very susceptible to powdery mildew; Taurus was less susceptible than Tasty Jade, but much more susceptible compared to most Beit alpha (or mini) type, long English (or Dutch greenhouse) type and American slicer cucumbers. Comparing three long English cultivars in our evaluation, Kalunga was more susceptible compared[Read More…]


Figure 3. Cucumber cultivar Taurus were grown in the front, cultivar Corinto was grown in the back.

Supported by NC SARE (LNC17-390), we are continuing research for improving high tunnel cucumber production. One of the biggest challenges for growing cucumbers in high tunnels in the summer is two-spotted spider mites. Dry and hot environments featured in high tunnels allow two-spotted spider mite populations to increase rapidly. The mites cause leaf yellowing, necrosis, and defoliation that interfere with plant photosynthesis. Yield can be significantly reduced. The pest also causes direct damage on cucumber fruit, resulting in a sandpaper-like texture to the rind (Figure 1). Early detection is the key for controlling two-spotted spider mites. As soon as two-spotted spider mites are detected, control efforts need to be taken. In the early stage, yellowish specks on the upper side of the leaves may be noticed (Figure 2). Turn the leaf over, on the other side of where the yellow specks are, you may find the presence of two-spotted spider[Read More…]


Basic Aspects of High Tunnel Soil Fertility Management – (Petrus Langenhoven, plangenh@purdue.edu, 765-496-7955) – Spring has arrived! Every high tunnel grower is now thinking of planting summer vegetable crops in high tunnels or has already planted. Whichever scenario applies to you, I hope that you have submitted soil samples or are in the process of submitting samples to your closest laboratory. Have you analyzed your irrigation water? It will be a good idea to send a water sample along too. There is a lot of important information locked up in your water and soil test results. The results will help you to plan and manage your high tunnel fertility program. Remember, growing in a high tunnel is like growing crops in an irrigated desert. Natural rainfall is unavailable inside your high tunnel and therefore all your plants water needs are satisfied through an irrigation system. Fertilizer needs could be addressed[Read More…]


Bolting of crops overwintered in high tunnels is common in the spring. ‘Bolting’ refers to lengthening and blooming of the flowering stalk. Bolting is often a problem because the quality of the marketable part of the plant declines. Also, plants subject to bolting are programmed to die once they complete flowering and seed production so yield will decline in quantity as well as quality. Sometimes bolting is not a problem because the stalk, buds, and flowers can be sold as a new product while they last; this is often the case with kale,  mustards and related crops. Crops susceptible to bolting include those in the mustard family such as kale, mustards, tatsoi, bok choy (pac choi), mizuna, turnip, radish, etc.; carrots; beets and in some cases Swiss chard; onions; lettuce; and spinach. (Figure 1)   Bolting is triggered by environmental conditions. Some plant types are triggered to develop flowers by[Read More…]


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High tunnels, though relatively new, have gained popularity over the past decade among specialty crop growers who want to extend their growing season. However, these environments can make crops vulnerable to the development of soil-borne diseases that reduce yield. This is particularly true for tomatoes, which are the most commonly grown high tunnel crop and can be highly susceptible to soil pathogens. For most field crops, rotation systems are already in place to combat a build-up of pests and pathogens. In field-grown tomatoes, for example, growers are advised to wait a period of 3 years before replanting tomato in a particular field to break the disease cycle. In high tunnels, rotation systems are more challenging to implement due to space limitations, which results in many growers employing a tomato-on-tomato system from one year to the next. This could be especially problematic for heirloom tomatoes, which are popular high tunnel tomato[Read More…]


Figure 1. Cucumbers were grown in a greenhouse in April 2018

Cucumbers are extremely sensitive to cold. Locally grown cucumbers are almost only available in the summer. While in Asia, without the use of fancy heated greenhouses, cucumbers can grow all winter. Growing grafted cucumbers with cold tolerant squash rootstock is one of the key factors making this possible. Since 2016, we started to evaluate opportunities of using grafted plants to extend early season cucumber production under protected cultural systems in the Midwest. We observed promising results in our research trials. However, knowing research trials can only tell part of the story, we initiated multiple on-farm trials across Indiana to better understand if and under what circumstances growers would benefit from this technique. This article discusses the lessons we have learned so far and raises questions that need to be answered. Heated greenhouses A pronounced advantage of using grafted cucumbers was observed in the situations that cucumbers were grown in soils[Read More…]


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