44 articles tagged "Greenhouses & High Tunnels".

It’s that time of year, where we are prepping high tunnels and getting back into the full swing of production, slowly, here in the Midwest. Many of you have already begun to transplant and may have encountered your first pests on these new crops. Aphids are one that remain a problem in high tunnels, and may even have plagued your winter production (Figure 1,2,3). Some keys to preventing or controlling these pests rely first on sanitation and then careful scouting. Try to remove any green bridge material that may already be infested before transplanting into the space. This includes weeds, lingering winter crops or residues. Having a week without vegetative hosts should get rid of any overwintering residents. After transplanting scout diligently, at least weekly, or more often on susceptible young transplants. Aphid infestations tend to begin on the growing points or younger tissues of the plant. Be sure to[Read More…]


Figure 2. Plants died in the second day after average soil temperature was 54 °F

Growers start to plant tomatoes in unheated high tunnels around the end of March in southern Indiana. Around that time, there may still be a few light frosts, or even heavier ones, like the one we just experienced in the past week. With additional help from row covers inside of high tunnels, temperatures normally can be maintained above 32°F. Tomatoes typically do not have problems with the short-term low temperatures. However, this may not be the case for cucumbers. Although they are both warm season crops, Cucurbits (cucumbers, cantaloupes, and watermelons) are much more cold sensitive than Solanaceous crops (tomato, pepper). From a temperature perspective, this article discusses important considerations for deciding the time for planting cucumbers in a high tunnel. The best condition to grow cucumbers is when soil temperatures are above 70°F. This situation may not happen until the middle of May inside of the high tunnels, according to our[Read More…]


Figure 3. A Japanese type cucumber grown in a high tunnel.

Cucumbers are produced with very different production systems. The ideal cucumber variety for process pickling production is not the variety used for greenhouse production. Choosing the suitable variety for a specific production system then becomes important. Where do you find recommended cucumber varieties for high tunnel production in seed catalogs? Some of the seed catalogs have a category called Greenhouse or Protected culture. Varieties listed in this category are recommend for greenhouse or high tunnel production. Other seeds catalogs may call this group Parthenocarpic hybrid or European slicer. Cucumbers listed under these names are also suitable for greenhouse or high tunnel production. A few technical words (parthenocarpic, monoecious, gynoecious) occur frequently in the descriptions of high tunnel-grown cucumbers. Understanding their meaning is important in choosing the right varieties. Parthenocarpic means that the plant can set fruit without pollination. Since pollinators are not required in this case, parthenocarpic is a desirable characteristic for cucumbers grown in protected[Read More…]


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This article is my response to a grower’s question about lowering soil pH in a high tunnel. The soil test indicated pH of the soil in his high tunnel was 7.7. The high pH could be partially caused by alkaline water he used to use for irrigation. The grower has changed the water source, but high soil pH is still a concern. ‘I have soil sample from the high tunnels if I could have your input on them I would appreciate it. I am concerned with the pH, should I use sulfur to bring it down, if so, how much?’ Following is my response to the grower’s question. My response is mainly based on the publication ‘Lowering Soil pH for Horticulture Crops‘. Purdue Extension HO-241-W. We have a few choices to reduce soil pH. Adding elemental sulfur is one way to do it. If you want to reduce soil pH[Read More…]


A grafted tomato plant grown in a high tunnel

Awareness of tomato grafting has increased tremendously in the past years. Some growers fall in love with this technology and apply it to every tomato they grow. While others find this technology is not cost effective. The growers who have successfully adapted this technology are often small-scale, high tunnel or greenhouse growers who have mastered the grafting technique. They graft tomatoes by themselves and often can achieve a high survival rate. In this case, the added cost for grafted plants is mainly the cost of rootstock seeds, which is roughly 30-50 centers per plant. A small amount of yield increase could easily compensate for the added cost. This is particularly true for tomatoes grown in high tunnels that often sell at a higher price. In situations that farmers buy grafted plants, the cost rangs from $1 to $3 per plant. Farmers would expect a high percentage of yield increase to compensate for[Read More…]


Consumers love cucumbers that are sweet, seedless and have thin skins. They are willing to pay high prices for the long or mini cucumbers sold at grocery stores. These cucumbers are often grown in greenhouses and shipped long distances. It will attract consumers’ attention if greenhouse type cucumbers can be produced locally in high tunnels, and be available in the early-season’s market. There are at least three benefits for targeting early-season cucumber production. First, prices are higher; second, there are less pest problems; and third, things are going slower in early seasons compared to in the summer. However, we all know that cucumbers love high temperatures and do not grow well when soil temperature is low, even in high tunnels. This is especially true for the greenhouse type cucumbers. The situation may be changed with the use of grafting technology. Using squash as rootstocks, we were able to harvest cucumbers[Read More…]


When we first began working in high tunnels about 8 years ago, most of the popular literature said that the tunnels would provide protection from most insect pests, other than the usual greenhouse pests like aphids and mites. What we found very quickly is that that information was untrue. We found very high populations of a variety of insect pests within our high tunnels. Caterpillars of various types seem to be especially problematic in high tunnels. Our theory is that the moths fly into the tunnel and can’t figure out how to escape, so the females just lay their eggs on the crop they can reach. The key to managing these caterpillars is regular scouting and treating early. For the crop you are growing, look for the products recommend in the Midwest Vegetable Production Guide for caterpillars, then check Table 16 on page 45 to see if it can be[Read More…]


Figure 1. A 30% black shade cloth was added to one of the high tunnels

Tomatoes growing in high tunnels are in the middle of or close to harvest. Developing and maturing fruit are under leaf canopies. On the top of the plants, many flowers are still blooming. These flowers will contribute to the second big harvest. Although tomatoes in June are most valuable, we certainly appreciate big, red and delicious tomatoes in July and August.  To ensure a sustained yield, it is important for these flowers to set fruit. The process of fruit set is very sensitive to excessively high temperatures. When temperatures rise above 100°F, even just for a few hours for a handful of days, tomato flowers may be aborted and fruit set fail. Night temperatures above 75°F may also cause tomato fruit set failure. In addition to fruit set, high temperatures affect fruit ripening process. Ethylene associated ripening decreases markedly at a temperature above 93°F. As a result, there might be an increasing number of[Read More…]


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Every grower will have to do some basic calculations when mixing a nutrient solution. Understanding some of the calculations will help you to apply the correct concentration of a nutrient or determine the concentrations of a combination of nutrients applied. In the previous article Taking Care of Plant Nutrition in Your High Tunnel-Water Hardness and the Removal of Unwanted Ions, we have discussed how to manage hard water, and unwanted high concentrations of sodium, chloride, iron, manganese and sulfur. Growers have different nutrient solution mixing and application options. Depending on the size of your high tunnel or greenhouse operation and the sophistication level of your nutrient solution application system, you might decide to use a single-bag mix (contains all needed elements), a two-bag mix (Tank A-calcium and iron, and half of potassium nitrate; Tank B-all other elements including phosphates and sulfates), or an individual element mix (individual compound fertilizers). The[Read More…]


It is essential, especially in hydroponics to start with a laboratory analysis of your source water. It is also important to do follow-up analysis throughout the year. Water quality can change especially where the water source is a well or a pond. In the article Taking Care of Plant Nutrition in Your High Tunnel-Water Alkalinity (Issue 627), we have discussed the importance of water alkalinity and how to correct high alkalinity levels. Additional elements of importance are Ca, Mg, S, Na, Cl, Fe and Mn. Knowing concentrations of these ions can help you to determine the need to purify water, leach or bleed more frequently, as well as to avoid these contaminants by choosing the appropriate fertilizer. Hard water might be generally associated with high alkalinity, but it is not always the case. Water hardness is a measure of the amount of dissolved calcium (Ca) and magnesium (Mg), expressed as if[Read More…]


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