Not quite ready for a traditional glass greenhouse? Check out the new array of lightweight mini-greenhouses with tiny price tags to match.
If you’re an avid gardener, you’ve probably fantasised about having a greenhouse—a lovely, warm, glassed-in garden getaway where you’d tend tiny seedlings, coddle delicate orchids, and harvest beautiful tomatoes, no matter what the weather. Then you checked the prices for traditional greenhouses, and your daydream popped like a soap bubble.
Dream no more. You can enjoy many of the advantages of a greenhouse for a fraction of the price—and in a fraction of the space—if you consider a mini-greenhouse. Ranging from small cold-frame structures to large walk-in freestanding types, these inexpensive greenhouses are designed to be semipermanent, lasting a few to several years.
This new breed of lightweight greenhouse might not have enough space and insulation to make it a great place to hang out for hours on a winter afternoon, but it does help you start seeds and cuttings, overwinter tender plants, grow out-of-season produce, and force spring bulbs into bloom.
Many mini-greenhouses are portable and easy to store during the summer. (Some even come with a storage bag.) Shop carefully and you can find one that takes less than 30 minutes to put up or take down. Some manufacturers even tout their mini-greenhouses as “pop-up.” It takes about as much time to put them up as it does a pup tent. These are ideal if you want to use them for only a few weeks: say for starting seedlings in early spring.
Portable greenhouses also give you flexibility on where to locate them. If you install a permanent greenhouse, you need to carefully consider the movement of the sun and the growth patterns of trees over the years. Most mini-greenhouses, on the other hand, can simply be plunked down wherever it’s sunny. If it’s not sunny enough, you can move them.
Many people want a greenhouse to hold collections of beloved plants, such as orchids or other tropical beauties. Temporary greenhouses are not as good for that. When they’re made out of flexible plastic, temporary greenhouses are not particularly sturdy, and they are harder to heat and ventilate. However, something as simple as milk jugs filled with water helps anchor some designs and also serves as passive solar heat. This method is reported to keep small greenhouses above freezing even when temperatures drop as low as 15°F.
Some determined gardeners install fans even in the flimsier sorts of greenhouses. If you choose a design with rigid plastic, it’s likely to have some type of automatic ventilation system. This will prevent delicate plants from cooking on a sunny day when you’re not around to open a flap or door.
Stormy weather is another issue. Smaller greenhouses can be anchored with bricks, small boulders, or soil staples. Larger ones need rope and stakes. Hail, too, can damage flexible plastic greenhouses. Some models have replacement covers and repair kits, though handy gardeners can do the repairs with clear glue and heavy clear plastic from the home improvement store.
A mini-greenhouse is a clever solution for the gardener who wants some of the advantages of a greenhouse without the steep investment. And come spring, when you’re tending your seedlings even as frost settles in, you may well agree.
Advantages: Small, portable, inexpensive. Ideal for starting greens directly in the ground and protecting flats of seedlings for a few weeks in late winter or early spring. Good for chilling pots of forced bulbs. Can be disassembled for storage. Variety of designs, including some that are sized to fit over a group of tomato plants.
Disadvantages: Can’t grow anything taller than several inches. Bending to open and close lid may be a problem for gardeners with limited mobility.
Price range: £20 to £90
Advantages: Fairly small. Excellent for a deck or patio. Radiant heat from the house provides even more protection. Multiple shelves mean more space than a cold frame—plus, no bending.
Disadvantages: Limited space. Hard to heat, though some may have additional insulating layers for an additional cost. Prone to tipping in wind, so you may want to weight down or wire or attach to a supporting structure.
Price range: £30 to £100
Pop-up or quick-assemble
Advantages: Lots of space for not much money. Most are large enough to walk into and you can even put shelves and/or stands in them. Most have designs that allow you to knock them down in a half hour or less and store easily. Can put directly on grass, if desired—no firm foundation required.
Disadvantages: Very prone to blowing, so be sure to anchor well. Also check design to make sure snow load won’t be an issue. Limited life of a few to several years.
Price range: £150 to £600
Advantages: Can be quite substantial. Good for decks and patios. They benefit from the radiant heat and insulation of the attached building. Can do a wide array of gardening in this type of greenhouse. Since it’s near electrical and water sources, you can install a fan, heater, or hydrant. One design fits over a door of a garage, shed, or house so you can walk directly into it from the building.
Disadvantages: Among the most expensive of the mini-greenhouses. Attaching to the house takes work and commitment.
Price range: £250 to £800
Advantages: Almost but not quite a traditional greenhouse, this one has economy and limited space in mind. Still light and temporary enough to put on a patio or deck, but more durable than those with flexible plastic shells. Could last a decade or more.
Disadvantages: Can’t knock down and store. More expensive than other types. Does best with a foundation of some sort. Gravel is usually acceptable, but brick, concrete block, or poured concrete is preferable.
Price range: £400 to £1,500
Do you need a greenhouse?
If you answer “yes” to more than a few of these questions, a greenhouse may be a great gardening resource for you.
Would you like to start more plants from seed with more success?
If you’re a seed starter, you know that half the struggle is getting those seedlings plenty of light so they grow fast, stocky, and strong. Most indoor grow lights are barely adequate. A greenhouse provides as much light as the sun does.
Do you want to get your cuttings off to a better start?
A greenhouse allows you to start more cuttings earlier and have better results. You’ll have larger, sturdier plants that will take off faster with less pampering come warmer weather.
Do you want to save money by overwintering tender plants?
Some of our favourite plants are marginally hardy. A mini-greenhouse, depending on the plant and your climate, allows you to gain approximately two hardiness zones if you grow the plant in a pot and overwinter it in the greenhouse. In colder climates, it’s a resourceful way to overwinter prized plants such as rosemary, fig trees, gardenias, jasmine, and citrus.
Do you crave more veggies earlier in the season?
Some greenhouses can be constructed with raised beds or set right on the soil. This allows you to start tomatoes and other produce weeks and even months earlier. Then, when temperatures are warm enough, remove the mini-greenhouse. (Charley’s Greenhouse and Garden, for example, makes a special mini-greenhouse tailored for growing tomatoes right in the ground.)
Do you enjoy forcing bulbs in winter?
If you plant spring-blooming bulbs in fall for forcing into early bloom during winter, a greenhouse may be helpful, depending on your climate. Keep it at refrigerator-like temperatures (40°F to 55°F) for at least 12 weeks to let the bulbs sprout. Then bring them indoors, where they’ll grow and bloom.