Everybody’s familiar with the giants of the greenhouse world—they hang out at the nursery centers, they’re used to produce part of our food supply and they’re the envy of every greenhouse gardener everywhere. But the truth of the matter is that not everybody wants the extra maintenance or expense that these monstrous glass houses require. For gardeners who just want to start some seeds for their outdoor garden or protect a few flowers, small greenhouses are an ideal solution.
Types of small greenhouses
There’s no hard and fast definition of a small greenhouse, but generally, people who use the term are referring to tabletop greenhouses, small portable greenhouses or small pop-up greenhouses. These structures are a bit nebulous in their definitions as well, but each type has some common characteristics:
Tabletop greenhouses, as the name implies, are small enough to fit on your tabletop. They’re usually used for seed starting, but may also be employed for grafting very special plants or increasing the humidity around specific plants to increase the chances that hand pollination will be successful. Tabletop greenhouses are easy to find in big box stores during the springtime, but can be ordered online any time of the year. They’re generally the least expensive option and are very no-frills.
Portable greenhouses typically use powder-coated steel tubing or molded resin to form a small structure around one or two stacks of shelves. They’re covered in a heavy plastic, usually clear or green-tinted, with a roll-up door. There’s only enough room in a portable greenhouse for the shelving and plants, so you can’t add heating or cooling equipment easily. These units aren’t terribly expensive, but can be difficult to place properly to prevent your plants from melting down in the heat of midday.
Small pop-up greenhouses have become neat solutions for the greenhouse gardener with limited space for a full-time structure. Although they’re not large, usually with a footprint measuring less than 4 feet by 6 feet, they’re very useful structures. Pop-up greenhouses can be erected on a gravel or cement base and stocked with shelving for a good approximation of a full-sized unheated greenhouse, or even placed over already planted gardens to help prolong the growing season when frost threatens.
Small greenhouse climate can be tricky
Although small greenhouses are great in the right situations, there are a lot of things they can’t do. Climate control is a huge problem with these tiny structures—and overwhelmingly why gardeners abandon the inexpensive units for full-scale greenhouses. Because they’re hard or impossible to heat, cool and ventilate, plants may suffer from sunscald, frostbite or excessive humidity—sometimes all in the same day. In short, they can only be considered very short-term greenhouse solutions, though sometimes that’s OK.
Small greenhouses, because of their light weight, tend to blow over or become unbalanced very easily, so you’ll need to have a plan for mounting them securely before the first pole goes up. They can usually handle mild winds, light snows, and reasonable rains, but extreme weather is right out.
If you’re looking for a quick and affordable way to start more seedlings this year or cover your newly planted shrubs, though, small greenhouses may be the perfect fit.