Imagine growing food in outer space, feasting on fresh, leafy lettuce during cold winter months, or getting 1,000 pounds of tomatoes from one plant. These are some of the visions that have drawn horticulturists and other scientists to research and practice hydroponics -- or growing plants without soil.
We've heard from indoor gardening teachers, "All of our bean leaves are dropping off-what could be wrong?" or "Do you know any activities with flower bulbs that I can use with my first graders?" Master Gardeners are a national network of resource people who can help answer these types of questions and enrich your classroom gardening effort.
Sure they're excited and having fun, but how does classroom gardening improve students' science and problem solving skills, content understanding, and attitudes toward learning? We're all facing increasing national and local pressures to identify what students are really gaining from different instructional efforts. Although standardized paper-and-pencil-type tests have been the norm, more and more educators are recognizing the limitations of these tools. They are particularly inadequate for measuring gains from active, inquiry-oriented learning programs.
For several years, Roger Crowley's third grade students in Montpelier, VT, have become silly about sprouts. They've written sprout stories, developed sprout characters, and magnified sprouts to project on classroom walls. The sprout project germinated one year when a social studies unit on pioneers sparked student interest in sprouts as a food source. Another year, students grew enough sprouts to start a small business. They developed a logo and advertisements, and took orders for sprouts from the school cafeteria and a local deli.
"It's been wonderful having the Master Gardener's support. I had never done classroom gardening before. I've learned so much from her, and we're able to combine my teaching strategies with her horticultural knowledge to produce some really nice projects."
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.
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.