Go down the internet rabbit hole for design ideas, then gather your supplies
How nice would it be to have sustainably grown vegetables or beautiful flowers year-round? That image is what many homeowners have in mind when they decide to build a small greenhouse in their backyard DIY.
Today, many companies make it easy. There are hundreds of awesome greenhouse ideas, kits, and pre-made designs you can shop for online to fit your space. If you want to assemble yours from scratch, be prepared to dedicate at least an afternoon or two to the planning phase.
Learn how to build a greenhouse and the many options you have for doing so in this step-by-step guide.
A small home greenhouse casts a wide net on many possibilities for homeowners with a green thumb. This job turns out best with careful planning—and perhaps calculated daydreaming— aligned with your budget, space, and gardening goals.
The cost to build a greenhouse can range from $500 for the lowest priced pre-made kit or reclaimed wood to as much as $10,000 plus for a high-end product. If you’re DIYing, the amount you’ll pay depends largely on the size of the greenhouse and the quality of materials you select.
Do your research and map out your space to help narrow down the scope of your project.
Your greenhouse options may be limited by how much space you have, as well as where you can reasonably place it in your yard. Ideally, a greenhouse should sit where it’ll receive southern exposure for more sunlight throughout the day.
That said, near a shady tree is actually an ideal location for a year-round greenhouse. In the summer, the shade will protect the tree from the hottest parts of the day. In the winter, when the leaves have fallen, your plants will get the extra sunlight they need to stay alive.
Generally speaking, greenhouse kit sizes will look like this:
Small greenhouse kits are typically 6-by-8 feet.
Medium-sized greenhouses creep up to 8-by-8 or 12-by-8 feet.
Large can be as big as 24-by-12 feet.
Luxurious and outrageous greenhouse designs can be, well, anything and everything.
A mini greenhouse, which looks more like a shelf that attaches to the side of your home, or even an indoor greenhouse, can both be great solutions for homeowners with limited outdoor space.
Lean-to and A-frame greenhouses give homeowners that classic greenhouse look. Alternatively, you can assemble a domed greenhouse very inexpensively out of plastic film.
The frame that makes up your greenhouse will likely be either wood, polycarbonate, or aluminum. Due to humidity, wood tends to wear out or start rotting after a few years. Polycarbonate is more affordable and will last longer than wood on average, but aluminum is your best bet for a build that’s going to last a decade or more.
Many homeowners opt for an aluminum A-framed greenhouse if budget isn't an issue.
The next consideration is which material you’ll use to insulate your greenhouse. The three most common types are:
Plastic/PVC
Fiberglass
Glass
Glass is the most expensive but longest-lasting. You can save money by using glass from old windows after construction or remodeling or by reaching out to a glass recycling center near you. Plastic film has about a four-year shelf life, and is easily the most affordable option.
If you’re not purchasing a pre-made greenhouse, you’ll need to draw up a rough outline of what the interior of your greenhouse will look like. Here are some guidelines:
19–24 inches is ideal for walkway space. This way, you won’t bump into plants.
Benches or shelves should be limited to 2–3 feet, or whatever allows you easy access to all the plants in the space from one side.
2–3 feet of overhead space is ideal, so you don’t have to crouch.
One square foot of space for every pot you plan to keep in the greenhouse is another popular guideline. Overshooting this number by a few square feet can allow your greenhouse gardening hobby to expand over time if you wish.
If you just want to focus on your green thumb, ask a local greenhouse contractor near you for help with your build.
Are you ready to build a DIY greenhouse? If so, start with the floor.
Pre-made kits generally come with this. But if you’re all in on the DIY build, you’ll need to either lay down pea gravel or pour concrete (the latter of which has to dry) before building a structure around it.
Pea gravel costs $350 on average for home improvement projects. In most cases, concrete costs more, coming in between $4 and $8 per square foot (including labor).
Next, start building the frame with your chosen material.
Some homeowners choose to build a standing rectangular wood frame as a base for their greenhouse, then use polycarbonate or aluminum frames to create a dome shape over the top. Depending on the job, you’ll need fasteners like a power drill and screws or hammer and nails.
Greenhouse covering goes up last. If you’re installing glass, be very careful with the panels and try to recruit help so as not to break them during installation. You can install plastic film in minutes if you set your frame up correctly.
For year-round greenhouse use, you’ll need a heating source to regulate the temperature inside. An electric greenhouse motor can be bought at home improvement stores starting at around $200.
More sustainable models, such as hotbeds made from decomposing materials, have become popular in recent years. This is yet another element you’ll need to decide on before beginning the job.
Hiring a pro to build your greenhouse makes sense when you’re buying an elaborate pre-made greenhouse kit or simply don’t want to do all the assembly. Since the job's difficulty relates directly to the size and complexity of your build, you’ll need to weigh that in your decision to tackle the job DIY.
