How to choose the best greenhouse for your needs

Greenhouse gardening has long been a commercial activity practiced by growers who need a controlled environment to produce crops of foods and flowers during what is otherwise an off-season. A backyard greenhouse is a simple walk-in structure that holds shelves full of plants sheltered from the cold while exposed to the sunlight so they can grow even in winter.

What are greenhouses made of?

Metal frames

Budget greenhouses typically use aluminum construction which is usually treated to resist rust. Better greenhouses use steel, usually powder-coated.

Plastic film walls

Most greenhouses use treated plastic film sheeting that should be replaced once a year. Plastic films are strong but thin and can be punctured easily by sharp objects. Better-made greenhouses have two layers of polyethylene film with a layer of air in between, providing better insulation than a single sheet.

Polycarbonate walls

More expensive greenhouses have rigid wall panels that are far sturdier than sheet plastic. Polycarbonate walls also do a much better job of insulating than plastic film.

Roofs

Because they’re made to be used in the winter, greenhouses need curved or sloped roofs to prevent snow from accumulating.

How are greenhouses shaped?

There are four basic types of greenhouse designs made for homeowners:

  • Tunnel greenhouses are built with curved roofs that provide maximum headroom in the middle. They have transparent or translucent walls and one or two doors.
  • Half-tunnel greenhouses are built to stand next to a wall where they are sheltered from the wind.
  • A-frame greenhouses have pointed, steeply sloping roofs like ski chalets. The roofs are made to shed snow instead of allowing it to accumulate on the roof while also providing headroom in the center aisle. This type has at least one door.
  • Shelf greenhouses take up only a small footprint with three or four stacked shelves.

What keeps greenhouses from blowing away?

Most backyard greenhouses are lightweight, and their flat walls allow lots of wind to push on them. They must be made stable to stand up to winds so they won’t be damaged or knocked over.

  • Tie-downs are crucial to keeping a greenhouse securely moored in high winds. Look for greenhouses that include stakes and ropes to secure them with, just as you would with a camping tent. Strong straps with ratcheting buckles make tie-downs even more secure.
  • Frames need to be sturdy enough to withstand the flexing that comes with high winds without giving way at a critical point.

How do I put a greenhouse together?

  1. Check your local zoning laws.
  2. Select a location. Choose a level spot that has good sun exposure, good drainage and at least some protection from wind. Position your greenhouse so the primary wall faces south.
  3. Get a friend to help. There are many pieces, some of which are heavy and hard to handle alone.
  4. Set aside enough time. Assembling a greenhouse will take a fair amount of time and effort.
  5. Check the parts against the list. You are putting together a three-dimensional structure with many connectors that must fit snugly and securely.
  6. Assemble the frame. Make sure all connectors and fittings are tightened according to manufacturer expectations.
  7. Add the walls. Attach them to the frame as per the instructions.
  8. Add the windows and doors and check for alignment.
  9. Add tie-downs. The best way to secure your greenhouse is to rope and stake it like a camping tent.

What you need to buy for your backyard greenhouse

Shelves

Only a few greenhouses come with shelves, so don’t assume from the pictures that yours does. Check to see what they’re made of and how much of a load they can support. Plastic shelves are lightweight and won’t corrode, but are not as sturdy.

Budget greenhouses

best Giantex Portable Mini Greenhouse

Giantex Portable Mini Greenhouse

This greenhouse includes four vertically stacked shelves in a 5-foot tall, heavily reinforced polyethylene package that takes up less than 4 square feet. The zippered door rolls up to provide access to your plants.

Where to buy: Sold by Amazon

best Wildgreen Mini Outdoor Walk-in Greenhouse

Wildgreen Mini Outdoor Walk-in Greenhouse

You get three tiers of shelving on each side of this 10-square foot greenhouse with zippered roll-up door and windows

Where to buy: Sold by Amazon

best Strong Camel 5- by 10-foot Walk-Through Greenhouse

Strong Camel 5- by 10-foot Walk-Through Greenhouse

This clever design sits against a wall in your home or garage for stability in windy areas. You get a galvanized steel frame with three tiers of open wire shelves, six on one side, double-stitching and a zippered door at each end. 

Where to buy: Sold by Amazon

Midrange greenhouses

best Outsunny 10- by 26-foot Walk-in Tunnel Garden Greenhouse

Outsunny 10- by 26-foot Walk-in Tunnel Garden Greenhouse

You get 260 square feet of sheltered growing space with this 7-foot-tall polyethylene greenhouse. It’s constructed with a powder-coated steel frame and has 12 windows for maximum exposure to the sun.

Where to buy: Sold by Amazon

best Outsunny 6- by 8-foot Walk-in Garden Greenhouse

Outsunny 6- by 8-foot Walk-in Garden Greenhouse

Rolling up the doors at either end lets you air out this 48-square-foot space with plastic sheeting that attaches to the powder-coated steel frame.

Where to buy: Sold by Wayfair

best Shelter Logic 10- by 20-foot Growit Greenhouse-n-a-Box

Shelter Logic 10- by 20-foot Growit Greenhouse-n-a-Box

The translucent cover is treated to diffuse light that reduces shadows and scorching, while the vents and roll-up side panels let plenty of air circulate around your plants. The patented metal ratchet tie-downs ensure your greenhouse is rock-solid, stable and durable.

Where to buy: Sold by Amazon

High-end greenhouses

best Monticello 8- by 12-foot Premium Greenhouse

Monticello 8- by 12-foot Premium Greenhouse

The vented A-frame design is supported by a sturdy aluminum frame and sheds rain and snow from the steeply sloped roof. It has hinged, lockable front and back doors and dual workbenches. Double-walled polycarbonate windows provide excellent insulation against the cold.

Where to buy: Sold by Home Depot

best Palram Canopia Chalet 10- by 12-foot Greenhouse

Palram Canopia Chalet 10- by 12-foot Greenhouse

Unlike the soft plastic walls of most greenhouses, this 120-square foot structure has rigid, unbreakable polycarbonate panels attached to a rust-resistant double-walled aluminum frame. With its slide-in flooring, this well-made product is as much a solarium as it is a greenhouse.

Where to buy: Sold by Amazon

 

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