One of the finest experiences my students and I have had is touring different children's gardens around the world through a Garden Video Letter Exchange. It's not as good as going in person, of course, but it's much better than not going at all. My Minnesota students have been amazed to see their video pen pals from Ecuador first growing corn and then standing in a banana jungle, and to watch their Georgia pen pals harvest peanuts and cotton.
Extend your growing season or experiment with different plant varieties
What to Grow, When
What you choose to grow, and when, depends on your curriculum goals and student interests, climate, and the type of greenhouse you have. See Greenhouse Climates for more information on different types.
Depending on your location and growing interests, you may need additional heating to supplement the heat generated through solar radiation. This adds to your expenses but allows you to extend your season. Use supplemental heating when the sun sets and the cold outside air begins to rob the greenhouse of its daytime warmth.
Venting is critical both to draw out hot air and to provide air circulation to reduce problems with pests and diseases. Vents can be manual, electric, or solar (these are triggered to open and close by the heat of the sun.) Ideally, vents should be placed both high and low to allow for proper airflow. They should be well constructed so they can be tightly closed on the coldest days. Exhaust fans placed high in the greenhouse help push hotter (upper) air out, while allowing cooler (lower) air to enter.
To maintain comfortable greenhouse temperatures, you may need to keep some light out of the greenhouse. Overheating problems are actually more common than underheating problems in greenhouses. Even in the North, a late spring temperature of 110° F has been recorded inside a greenhouse on a sunny day.
You can use various methods to block some of the sun's rays. These include:
Air - Plant growth requires heat. Temperature determines how quickly plants take up water and nutrients, their rate of photosynthesis, and their growth. Maintaining a comfortable air temperature for your plants can be a challenge. Generally, 50 to 60°F is a minimum temperature for greenhouse plants, while 85°F is the maximum. Plants generally do best with a 10- to 15-degree drop between day and night temperatures.
Light provides the energy necessary for plants to produce food through photosynthesis. Even though the amount of light inside your greenhouse usually depends on the amount of natural sunlight available, it's helpful to understand a bit about plants' light needs.
The following greenhouse characterizations are based on the temperature that can be maintained inside the greenhouse. They range from the least to the most expensive to build and maintain. Refer to this information when reviewing what you want to grow in your greenhouse.
Greenhouse environments require some control and monitoring
While a greenhouse can provide a delightful environment where living things thrive, it is an artificial environment in which you attempt to control as many factors as possible for the benefit of your plant denizens. It helps to recall what actually makes plants grow. Plants convert light into energy (sugar) during photosynthesis. This process requires light, carbon dioxide, temperatures between 45°F and 85°F, and water.
The material that covers a greenhouse and through which the sunlight passes is called glazing. There are many types available, each with advantages and disadvantages. These include glass, acrylic, polycarbonate panels, polyethylene films, and fiberglass. If you're building, buying, or reconstructing a greenhouse, you'll want to talk with experts and manufacturers about the pros, cons, and costs of various materials.
Kids Gardening and the National Gardening Association actively work with schools and communities across the country to provide educational resources and build gardens to promote health, wellness, and sustainability.