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Most gardeners would love to own a greenhouse. This appeal may be strongest in cold climates, but being able to grow an endless supply of sturdy little seedlings is a pretty appealing concept no matter where you live. And what gardener isn't intrigued by the idea of having a tropical environment filled with orchids, citrus and jasmine; or wouldn't relish the opportunity to pick fresh salad greens and vine-ripened tomatoes on a cold winter day. There are now dozens of affordable, well-constructed greenhouses on the market, as well as a full range of accessories that make greenhouse gardening easier than ever.
Owning a greenhouse can give you the opportunity to grow plants from all over the world. But before you stock up on potted citrus, orchids, cacti, scented geraniums and bromeliads, you need to stop and think about what sort of growing environment you will actually be able to provide. A common mistake made by beginning greenhouse gardeners is to fill the greenhouse with any plant that piques their interest.
An eclectic assortment of plants such as this may look fine for a few months, but they will soon begin to suffer. Some plants need cold nights, some need warm nights. Some like lots of bright light, some require filtered shade. Some need water twice a day, some only every few days. The challenge is to decide what sort of environment you will be able to provide, to take advantage of the microclimates within the greenhouse, and to choose plants that will thrive in those conditions.
If you plan to run your greenhouse year-round, you first need to determine what temperature range you want to maintain - both in winter and in summer. Wintertime temperatures ranging from 40 to 60 degrees F may be ideal for growing salad greens, herbs, camellias and for overwintering tender exotics. But these temperatures are too cold for producing healthy tomatoes, gardenias and tuberous begonias.
During the summer months, bright sun and daytime temperatures of 85°–90°F may be fine for potted tomatoes, bananas, figs, and geraniums, but alpine plants, African violets, and many types of orchids will not tolerate the heat.
Within any greenhouse, there are certain areas that are hotter or cooler, brighter or shadier. By taking advantage of these natural microclimates, you can provide optimum growing conditions for a wider range of plants. Shade cloth, lathe, small fans, propagation chambers, heat mats, and other devices can also be used to help create and manage these microclimates.
Your climate, the type of greenhouse you have, and the amount of time and money you are willing to invest in heating and cooling, will determine what sorts of plants you'll be able to grow successfully.
This may seem like a simplistic question, but function is really the most important factor in determining the type and size of greenhouse you choose.
An attached greenhouse or sunroom is the right choice if you want a place to read and putter among potted plants. For starting seeds, a freestanding polyethylene-covered hoop house can probably give you everything you're looking for. If your objective is to have a nearly year-round supply of fresh greens and herbs, you may want to consider a solar greenhouse that requires little or no supplemental heat.
Can you imagine yourself tending an extensive collection of orchids, propagating begonias and experimenting with oleander and passiflora? If so, you'll want a well-insulated, professional-quality greenhouse that can be temperature-controlled year-round, with running water, a power source for supplemental lights, active ventilation and plenty of room for expansion.
Appearance may also be an important consideration. Will you be happy with a polyethylene hoop house, or is it important that your greenhouse be a more aesthetically pleasing addition to your home and your landscape?
Climate and location are crucial considerations. One reason greenhouses are so popular in England is that their climate is far more moderate than what most of us must cope with here in the U.S. Operating a year-round greenhouse in Vermont or Minnesota usually requires an insulated foundation, double glazing, insulating shades, buried power and water lines, and a serious financial commitment for heating.
In the summer, maintaining a plant-friendly environment may require shade cloth, multiple fans and a misting system. But people who do have a greenhouse, and have tasted the pleasures of being able to fuss around in their own warm, plant-filled jungle, would be quick to argue that the benefits outweigh the challenges.
Last updated: 3/4/19
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