Cultural Practices

Greenhouse Cleanup

It is best to clean greenhouses as they become empty rather than to wait until just prior to the spring growing season. Cleaning early will eliminate over-wintering sites for pests and reduce populations for the next crop cycle. Greenhouse pests will overwinter in weeds and protected areas in unheated greenhouse, especially if the winter is unseasonably warm. Remove leftover plants and debris and clean the floor of soil, organic matter and weeds. Clean areas around furnaces and along side walls where small weeds are usually found.

Cleaning Containers

While some growers clean and re-use pots, trays and flats and it is important to do it properly. Plant pathogens such as Pythium, Rhizoctonia and Thielaviopsis can survive in root debris or soil particles on greenhouse surfaces. If the previous crop had a disease problem, then avoid re-using those containers. It is also a good idea to avoid planting crops that are prone to Thielaviopsis problems, such as calibrachoas, in containers that have been previously used.

Scheduling a Greenhouse Tomato Crop

Greenhouse tomatoes are usually scheduled to come into production when field tomatoes are not available. In Northern sections of the country, such as New England, the field production season occurs late in the summer and is short in duration. As a result, greenhouse tomato growers in New England, find they can market greenhouse tomatoes through most of the summer and still get a good price. The time interval between sowing a crop and harvesting ripe fruit will vary with the season since the rate of seedling and fruit development are affected by temperature.

Storing Growing Media

Many problems can arise from improperly stored growing media such as becoming contaminated with weed seeds, insects or chemicals. The pH or soluble salts could be too high at time of planting or it could be very dry and hard and difficult to wet. Here are a few guidelines for proper storage for the upcoming growing season.Store growing media in a cool, dry, low-light environment. If possible, store growing media inside a building with a clean floor (not the greenhouse).

Growing Spring Crops at Cool Greenhouse Temperatures

Cool outdoor temperatures continue and energy costs are high. Some things to consider if you are growing crops cooler to save energy costs:

Seed Germination: Don’t skimp on heat here. Temperatures too cool during seed germination will delay germination, reduce percent germination and decrease the uniformity. For most species, germination media temperature should be 72F-76F. After a crop is established, most plants will tolerate non-optimal temperatures more easily.

Transplanting Tips

Handling purchased plugs

Upon arrival, open and unpack the boxes immediately and check the physical condition of the plants. Inspect plants for root and foliar diseases and for insects and mites. Report any damage or discrepancies immediately to your supplier (most companies want to hear within 24 hours). Take a picture!

Reducing Humidity in Greenhouses

It is important to properly water plants and reduce humidity in greenhouses to prevent and manage Botrytis. When irrigating, apply just enough water to prevent excess water on the floor, and water early enough in the day to allow plant surfaces to dry before evening. The highest relative humidity in a greenhouse is generally found inside plant canopies, where moisture is generated from transpiration and trapped due to insufficient air movement. Adequate plant spacing and mesh benches will help to improve air circulation at the plant level.


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