Greenhouse Gardening

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.

Generally speaking, a greenhouse that can maintain a minimum of 60°F at night can grow almost any crop year-round. Most school greenhouses have some limitations, but think of the greenhouse as a microclimate of your outdoor growing conditions. You will be more successful if you match the needs of the plants you grow to your particular greenhouse conditions, just as you would consider your hardiness zone for growing plants outside. It would be quite frustrating, for example, to attempt to meet the needs of a banana tree (which requires bright light and warm temperatures) in a cool northern greenhouse.

Below you will find some plant suggestions for your greenhouse. What you can grow varies seasonally. Remember to check for pests before bringing any garden plants inside.

Fall Possibilities

• bulbs for forcing
• lichen and moss terraria
• seedlings of cool-season crops (Chinese greens, collards, lettuce, herbs) to put in greenhouse beds
• plants retrieved from the garden--experiment by digging up some annual flowers, vegetables, or herbs to see what survives the change

Winter Stalwarts

• plants harvested from the fall garden
• forced branches of pussy willows, forsythia, apple blossoms if you have a heated greenhouse or live in a warm climate
• tender perennials to overwinter if you have a cold greenhouse
• nothing, if you have an unheated greenhouse in a cold climate

Early Spring Dandies

• seedlings for outdoor gardens
• herbs, vegetable plants, flower plants for plant sale
• seedlings for warm-season crops (tomatoes, melons, cucumbers) to grow in greenhouse beds through the summer

Summer Sweeties

• warm-season crops (tomatoes, cucumbers, eggplants, melons) in greenhouse beds, particularly in areas with a short growing season
• perennials from seed or cuttings
• tropical crops (figs, citrus fruits, bananas)

If Not Bees, Who?

In nature, flowers are pollinated by insects, wind, birds, bats, and so on. Without natural pollinators in greenhouses, who does the work of moving pollen from the male to the female flower parts, so fertilization and fruit and seed production can occur? Fortunately, many crops that produce edible fruits or seeds have both stamens (male parts) and pistils (female parts) in the same flowers. Pollination occurs easily since the parts are arranged to facilitate pollen transfer. Greenhouse crops such as tomatoes, peppers, and beans are in this category. You can help pollinate them by shaking them gently from time to time. Special European varieties of greenhouse cucumbers are designed to bear fruit without pollination. If you and your students want to try to "play the bees," you can do so with regular garden cucumbers, melons, or squash.