GREENHOUSES
Grow about anything you want in micro-environment

April 27, 2012

by Bryan Fisher, Victoria County Master Gardener Intern

edited by Charla Borchers Leon,
Victoria County Master Gardener
Gardeners' Dirt
PHOTOS BY BRYAN FISHER/VICTORIA COUNTY MASTER GARDENER INTERN
This greenhouse belonging to James Mikulik, of Shiner, who is currently enrolled in the Gonzales County Master Gardener Program, was assembled from a store-bought kit. "Always buy the next size larger," he said.
The Victoria County Master Gardener Association greenhouse is located at Victoria Educational Gardens and is used in large part for propagating seedlings and cuttings for spring and fall plant sales.
Work and growing areas in the Master Gardener greenhouse at VEG are equipped with drip irrigation hoses, fans and a shade cloth. Stop by to inspect the greenhouse anytime.
Whether you have seen one in a movie, have seen them at the nursery or a home improvement store, or visited the one at the Master Gardener Victoria Educational Gardens, you could be wondering if you would enjoy the benefits of a greenhouse.

A greenhouse provides protection for tender plants against the elements like cold, wind, heavy rains and pests.

MICRO-ENVIRONMENT

A greenhouse creates a micro-environment by its cover, letting light in and keeping in air that is heated on a cold winter day. Of course, if you plan to use it during the warmer days, you will need to exhaust this same heat.

This covering, which includes a frame for its own support, also protects the plants inside from the elements. A well-drained floor closes in the bottom of your greenhouse.

GREENHOUSE USES

You can grow about anything you want in a greenhouse environment; you are just limited by size. You can use it to start spring vegetable garden plants from seeds, protecting them from a late frost. You can use a work area to start your plant propagations from cuttings, and then use the growing surfaces until you are ready to move them to their final place in your landscape.

With the right equipment, you can even create your own micro-environments, like a rain forest for growing orchids, desert for growing cacti or whatever you can imagine.

LOCATION

Location is important, depending on its intended use. A good location will need access to water, electrical power, good drainage and air flow. Like with a garden, the morning sun is important - and in our hot, South Texas climate, you should pick a location that is shaded from late afternoon sun.

COOLING, VENTILATION

An important requirement for a working greenhouse is cooling and ventilation. Without proper ventilation, your greenhouse will get hot during the day, just like your car on a sunny day. Your choices are plain manual vents or side covers which work well if you are using it during late winter.

VENT OPENERS

Pneumatic vent openers are an inexpensive way to release the heat automatically. They work when the air inside expands and forces a vent open and when the air cools, the unit closes the vent.

With electricity, a thermostat control and exhaust fan can provide your greenhouse with automatic vent control during the day. Adding a heater will also give you control over winter nights.

MISTERS, SHADE COVERS, WALL THERMOMETER


If your plans include creating a climate inside that is cooler than the typical summer day, then evaporative cooling in the form of misters and cooling pads will be needed. Shade cloth is a must if you plan to use the greenhouse in the hottest months like July, August and sometimes in September.

Don't forget a wall thermometer to help control the temperature.

EQUIPMENT OUTFITTING

Work space and growing areas are important for your ease and convenience.

Work space amenities

Having surfaces that allow you to work while standing along with a sink and/or wash surface are added amenities if space allows. Work surfaces should be easy to clean, and growing surfaces should have open galvanized wire to allow for drainage.

Watering equipment

Watering is very important, and in smaller greenhouses a water pail may suffice. In the larger ones, you should consider drip irrigation on timers. Misting equipment will work for water with some plants. Misting can also be used for cooling during the hottest part of the day.

Covering types

If you like saving money and you are good with tools, there are a lot of plans and even do-it-yourself kits available online. They use wood or PVC for the structure and polyethylene film to cover it. Make sure the film you use is UV stabilized.

Store-bought kits will have either polycarbonate panels or polyethylene film for the cover and galvanized metal or aluminum frames. You could assemble store-bought kits by yourself, but the bigger it is, the more likely you will need help. Check the recommendations from the seller.

The pre-engineered units will need to be erected by a contractor to keep the warranty enforced. You may want to select your greenhouse based on the frame if you plan to have hanging plants.

Flooring with good drainage

Whatever type you decide to use, make sure you create flooring that provides for good drainage, as all of the water runoff ends up on your floor. Consider gravel and sand with a weed blockage if you are doing it yourself. The pre-engineered greenhouse will have suggested foundation and flooring requirements.

CARE FOR GREENHOUSE


Regular maintenance is required to keep all of your equipment in good working order. Take care to clean all items used with a soap solution to keep out unwanted pathogens. If you are using polycarbonate panels, a yearly inspection of seals is a good idea, while a polyethylene film, which is damaged by UV, may need to be replaced every three to five years, based on the manufacturer's recommendations.

Whatever choices you make for a greenhouse, I hope you decide to look into creating your own micro-environment.
GREENHOUSE CREATES MICRO-ENVIRONMENT

Location - Catch the morning sunshine and afternoon shade
Covering - Plant protection and traps heat
Flooring - Excess water drainage
Ventilation - Fresh air and cooling
Watering - Drip irrigation to reduce work
Growing areas - Easy access to plants
Work areas - Easy access for humans

********************************************
FOR MORE INFORMATION
Use a feature and the word "greenhouse" in your search engine on the web,or visit these links:

~
Texas AgriLife Extension website ~

~
Texas Greenhouse Management Handbook ~
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or vcmga@vicad.com, or comment on this column at www.VictoriaAdvocate.com.