Things You'll Need
Shelves or benches
A greenhouse is a great way to be able to produce food and flowers all year, no matter what the weather is like outside. Many people have a greenhouse structure of some sort, or would like to get one, but they don't know what to do to begin growing. There are a few key essentials that will help an aspiring indoor gardener get started with a greenhouse.
Check the average temperature in your greenhouse. Plants will not grow well if it is too hot, above 85 degrees F, or too cold, below about 55 degrees F. These temperatures won't kill your plants, but they will slow down their growth rates.
Set up ventilation for your greenhouse. This is essential if it is quite warm inside, but adequate ventilation also helps reduce disease problems in a greenhouse. At least two fans placed near the top of the greenhouse will help to keep the air moving. Set one so that it blows fresh air into the greenhouse and another so that it acts as an exhaust to blow stale air out. You can roll the sides up on a greenhouse with a plastic film cover when the weather is very warm.
Place benches or shelves along one or both sides for holding smaller plants. These are especially useful when you want to use your greenhouse to start seedlings before transferring them out to your garden for the growing season. You can skip this step if you prefer to plant directly into the soil in your greenhouse and won't be starting seedlings there.
Provide plenty of light for your plants. If you are trying to grow vegetables in the middle of winter in your greenhouse, you will need to use appropriate types of grow lights, such as high-pressure sodium lights. If you just need some extra light to help your seedlings get started, cool white fluorescent lights suspended directly over the seedlings will be adequate.
Select plants that will thrive in the greenhouse during the times you want to be growing. Choose warm-weather, heat-tolerant crops such as tomatoes, eggplant and peppers during the warm months. Grow cold-hardy, cool-weather crops such as lettuce, chard, scallions and spinach in winter months. Proper plant selection will help to minimize both your heating and cooling costs.
Prepare the soil by adding amendments, such as well-aged compost, commercial fertilizer and sand, to create soil that is suitable for your plants. If the soil is heavy and full of clay, mix in plenty of compost to help loosen it up. If the soil is light enough and water can flow through it freely, add a good-quality commercial fertilizer to build the nutrient reserves in the soil.
Plant the seeds in rows in the greenhouse. Mark the locations carefully, so you know what you have planted. Keep your plants well watered, but do not overwater.
Adjust the greenhouse temperature as necessary by turning the fans on and off, opening the doors and rolling up the sides, if conditions require. Your plants will grow well and be ready for you to harvest when they mature.
A faucet inside your greenhouse will make watering chores much easier.