Are You Ready to Build a DIY Greenhouse?

Carolyn Doyle
Written by Carolyn Doyle
Updated March 31, 2017
Light shining within rigid-panel greenhouse
If you love to garden, a rigid-panel greenhouse may be on your wish list. The polycarbonate panels are more durable than flexible coverings, and the heavier structure can better withstand gusty winds and snow accumulation. (Photo ©Getty Images/Johner RF)

If you feel comfortable tackling DIY projects, there are plenty of greenhouse kits and plans to choose from.

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Do you like gardening? If so, perhaps you’ve built a cold frame, or have a small greenhouse with a flexible cover.

But maybe you’re wondering if you’re ready to take your garden to the next level.

Building a DIY greenhouse

Avid gardeners like to start seeds early in the spring, and extend the growing season for their precious plants well into the fall. Cold frames and small greenhouses, with vinyl or polyethylene coverings, help accomplish this. 

But if you crave more space, or just want something a little sturdier, maybe you’ve daydreamed about building a “proper” greenhouse for growing plants.

The glass greenhouse is a sturdy classic. It’s also the heaviest and most expensive greenhouse option — and the most demanding. A glass greenhouse requires a proper foundation and a heavy-duty frame, due to its weight. 

A plastic greenhouse is a less expensive alternative. If you have some prior building experience, a small DIY greenhouse made of rigid polycarbonate panels is not too difficult to construct. Doing the work yourself can save money.

First things first

Consult your HOA and local building codes to see what type of greenhouse you’re allowed to build on your property, and what regulations may apply, such as obtaining a building permit. Also review whether you can extend utilities to the structure.

A rigid-panel greenhouse: the basics

Advantages: Rigid polycarbonate panels are more durable than flexible coverings; heavier structure can better withstand gusty winds and snow accumulation.

Disadvantages: Compared to a flexible small greenhouse, a rigid-panel greenhouse is more expensive; assembly is more difficult, and it’s not portable.

Cost: Kits start at just under $400 and can run up to several thousand dollars. If you like to DIY, using spare building supplies and constructing from scratch can save you money. 

How big? Typical sizes can range from 4-by-6 to 8-by-12 feet, and some can be larger. 

Location: You’ll want to construct your greenhouse on a firm base, such as gravel, wood or concrete. 

Utilities: Don’t build beneath power lines! But if you’re planning to use LED grow lights, heaters, fans or a watering system, consider how you’ll access electricity, and whether you will need to extend water lines to the greenhouse. 

NOTE:  Always check with the proper agencies before digging, to avoid damaging underground cables or lines. Making a free call to 811 — the nationwide “Call Before You Dig” number — is an easy way to do this. 

Greenhouse kits

Rigid-panel greenhouse kits are a good option if you’re not ready to tackle building a greenhouse completely from scratch, but are comfortable using basic hand tools to assemble the structure.

Polycarbonate greenhouse kits include an aluminum or wooden frame and clear or diffused polycarbonate panels, which may snap in place or be installed in frames with silicone caulk. 

Some models are designed to be expandable. Small models can be constructed in a weekend or so, if you have someone to help.

The 3-sided greenhouse

Want to keep your greenhouse close to home? A three-walled model that you set up against an exterior wall of your home or garage is a simple, cost-effective option. Whether you assemble one from a kit or build your own, a three-sided greenhouse keeps your plants close at hand. Ranging from walk-in structures to modest lean-tos, the three-sided models can save you space, time and money.Size: Three-sided greenhouse kits can range from 4-by-6 feet to 6-by-14 feet, and cost from $400 to $2,000.

Building a DIY greenhouse from scratch

It only takes a little online research to discover that greenhouse owners are amazingly resourceful. Taking a virtual tour of your DIY greenhouse options, you’ll find greenhouse plans, suggestions and hacks galore. 

There are plenty of photos online of greenhouses and lean-tos constructed from found or salvaged materials such as old window frames, pallets and doors. 

Building a rigid-panel greenhouse from scratch allows you to customize, whether you want a door wide enough for a wheelbarrow, or extra supports for hanging plants.

Questions to consider

Still wondering if this is a project you can take on? Ask yourself these questions:

•  Can you work from a diagram?

•  Are you comfortable using power tools? Do you have the equipment you will need? This can range from ladders, pliers and wrenches to a post-hole digger (for framing a sturdy base with posts anchored in concrete).  

•  Can you perform handyman and construction tasks such as framing, hanging a door and installing a vent?

•  Whom can you call? You’re likely to need a helper or two, especially when constructing larger models.

•  Do you have the time? Building a small greenhouse from scratch may take a couple of weekends or a couple weeks, depending on the size and complexity of the design.

Shaping the space

There are as many devices to help you manage your new greenhouse as there are hybrid tomato varieties. Polycarbonate greenhouse design features may include integrated shelving, pre-hung doors and double-layered clear or diffused panels (also called glazing). 

Roll-up shades on the outside of the greenhouse can protect tender plants from too much sun. Solar-powered vents that open automatically when the greenhouse reaches a certain temperature can keep plants from getting too hot. Other options for your new greenhouse include:

• Heat mats for seedlings, and heaters to control air temperature.• LED grow lights.• Fans for air circulation.• Misting systems for plants.

Have your built a DIY greenhouse? Share your experience in the comments section below.

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