Greenhouses come in a variety of sizes, construction materials, and accoutrements from large structures that can produce commercial quantities to six by ten foot structures and cold frames. For the home gardener in Texas, hobby greenhouses are usually used in the cool weather months to extend the growing season and start seedlings. Cooling greenhouses in Texas summers is rarely practical for the home vegetable gardener.
Texas Greenhouse Structures
According to the Texas A&M greenhouse management guide, “Ridge and furrow houses provide the greatest efficiency in crop production. Aluminum is the most durable and commonly used framing material for commercial greenhouse structures. Double sheets of polyethylene film is the most economical covering material available for Texas producers.”
Venting and Heating Hobby Greenhouses in Texas
Greenhouses get quite warm even on cool winter days. So a gardener needs to be able to vent the greenhouse either by leaving doors open or having vents that can be open during the day and closed at night.
Heating a hobby greenhouse can be difficult and costly. However, many home gardeners have found that the heat generated by large Christmas lights is sufficient to keep plants in a closed greenhouse from freeze or frost damage. A hobby greenhouse gardener can also use low wattage heat mats under the plant trays to raise the temperatures 10-20 degrees which is sufficient to protect plants in most Texas winters.
Watering and Humidity Control in Hobby Greenhouses
Greenhouse plants need access to water. Depending on the size of the greenhouse, watering plants may be as simple as using a sprinkling can or soaker hose when the plants need water. However, unless the greenhouse has its own connection to outside water with pipes protected from cold temperatures, the home greenhouse gardener will be transporting water in cans or connecting and then disconnecting the hose each time.
Leaf transpiration and condensation may create too much humidity in the greenhouse which encourages pests and diseases. For the home gardener, the best humidity controls include venting to release moisture including occasionally using a fan for air circulation and adequate plant spacing to allow drying through air movement. One may also choose a greenhouse plastic covering that has been treated to prevent condensation.
Greenhouse Pest Control and Disease Management
Insects and disease are part of gardening, even in greenhouses. Here are a few simple things you can do to reduce the insect and disease problems in a hobby greenhouse. Take heart that in Texas winters there are fewer insects out and about waiting to attack.
• Cover all soil floor surfaces with concrete, black plastic or weed barrier, advises the National Sustainable Agriculture Information Service.
• Keep all gardening tools clean
• Check plants frequently for insect or disease problems—a small infestation can move quickly in a greenhouse
• Use insecticidal soap against aphids which are a common greenhouse pest
• Remove standing water where pests can breed
• Maintain adequate plant spacing to allow air drying of leaves
• Remove infected plants from the greenhouse and destroy them
• Place diatomaceous earth around benches and plants stands to control slugs and snails
An excellent resource on greenhouse integrated pest management is offered by the University of Illinois Extension Service.
A hobby greenhouse allows a Texas gardener to have salad crops and culinary herbs available all winter. It is also an ideal place to grow favorite, but hard to find, seedlings for later transplantation into the vegetable garden.