Growing your own plants from seeds or cuttings requires nothing more than a dedicated area of your yard or house where you will be sure to check in daily. I’ve used everything from tables in front of a sunny south-facing window indoors to jury-rigged cold frames and north-facing patios outdoors. But a small backyard greenhouse is fun if you enjoy propagating plants year-round and watching them grow.
Before you take on the cost and responsibility of a greenhouse, consider whether you have the space, what you like to grow and how much you will use it.
For small suburban yards, a 6-foot-by-8-foot or 7-foot-by-9-foot greenhouse is a good size. It doesn’t take up too much space, and it can hold a lot of plants – two 8-foot-by-2-foot benches as well as the floor space under them.
Midsummer is the best time to survey your yard and decide if you can cede space from plantings, patio or play areas for a greenhouse. A perimeter foundation or a solid base can keep critters from tunneling into it. Pay attention to required setbacks, and allow enough space around it so that you can safely reach all areas of the greenhouse roof with a freestanding ladder. Plan to run an outdoor extension cord for a seed-starting heat mat and a fan.
Although it’s a lovely, warm place to work in cold, rainy or windy weather, a small greenhouse can get as hot as a closed car sitting in the sun all day. It’s important to monitor temperature and humidity daily to learn when to open and close vents. Professional greenhouses have built-in fans and misting systems to keep plants happy in warmer weather, but for a hobby greenhouse, those systems are usually not practical. I used shade cloth on the greenhouse all summer and fall, kept both vents wide open and added a screen door to keep temperatures more reasonable during the warmest months.
Don’t let this valuable space become a storage shed! Summer is the best time to clear the greenhouse, sweep it out, reorganize the potting area and other supplies and get ready for the fall growing season. For the two years I had it, my greenhouse was jam-packed with edibles, natives and succulents year-round except in the heat of summer.
In the fall, when garden beds overflowed with summer vegetables, it was a protected growing space for winter-vegetable seeds and transplants, ready to plant out as soon as the summer crops declined.
Likewise, in the spring, the greenhouse enabled me to grow tomatoes and peppers from seed, starting in February or March, ready to plant out in April or May. At times, insects were attracted to the tender plants growing in close quarters, but I watched diligently to prevent infestations.
For native-plant cuttings started in spring and fall, the greenhouse offered a well-organized potting bench, with a surface at a comfortable working height and all necessities at hand. Most cuttings stayed in the greenhouse until they were rooted.
Tiny succulents that needed extra care also benefited from the protected environment.