Greenhouses provide enclosed, protected growing situations for both commercial growers and hobby gardeners, and can be extremely valuable in any growing situation. These controlled environments give gardeners in cold growing zones a chance to grow warm-weather plants, flowers, vegetables and fruits. A greenhouse also gives any gardener the option of lengthening a summer growing season, or growing year-round. To grow effectively in a greenhouse, though, gardeners must keep some specific guidelines in mind.
Prepare the greenhouse before you start using it, to keep problems from popping up. Check the equipment—fan, heater, lights and thermometer—to make sure it's in good working order. Check for any cracked seams or windows, and use caulk, available at home improvement shops, to seal the cracks. If you're using the greenhouse for winter growing in a cold zone, consider making some homemade insulation by taping bubble wrap to the outsides of the windows, to hold heat inside.
Place plants appropriately in the greenhouse. Make sure the plants that require full sun are in areas where they'll get full exposure to natural sunlight or the artificial lights. Place hardier plants near the outside of the greenhouse, where temperatures are slightly cooler, and keep the more sensitive plants in the middle of the greenhouse, where they receive better protection.
Maintain the plants as necessary, with watering and appropriate light exposure. When temperatures drop and the days grow shorter during winter, use the heater, fan and artificial lights to supplement natural conditions for the plants. If you're using the heater and fan, increase waterings to keep the plants and trees from drying.
Maintain the humidity in the greenhouse during winter growing by spreading the plants and soil with the hose once a week. Keep all windows and doors closed, to keep humid air from escaping to the outside. A crowded greenhouse will stay more humid than an empty one, as plants release water vapor during their everyday processes. This humidity aids all the plants during winter survival.
Watch the greenhouse for mold and fungus growth, which may occur whenever temperatures and humidity are higher inside the greenhouse than outside. Look in cracks and corners for mold or fungus, and eradicate it before it can spread to the plants.