How to Build a Small Greenhouse and Gain Inspiration in 9 Simple Steps

Ben Kissam
Written by Ben Kissam
Updated February 1, 2022
Family gardening outside
Photo: FangXiaNuo/Getty Images

Go down the internet rabbit hole for design ideas, then gather your supplies

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Project Difficulty: 3/5 Perfect for handy homeowners.

Time to complete: 3+ hours

Tools and Materials Required: 

  • Pen and paper

  • Greenhouse kit or

    • Greenhouse frame materials (aluminum, wood, or polycarbonate)

    • Greenhouse covering materials (plastic film, fiberglass, glass)

    • Greenhouse floor materials (pea gravel or poured concrete)

  • Fasteners (screws or nails)

  • Power drill/hammer

  • Tape measure

  • Circular saw

  • Safety goggles

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.

1. Determine Your Small Greenhouse Budget and Goals

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 $40 for a temporary domicile, to under $1,000 for one made from basic materials. Pre-made greenhouse kits can make the job easy for you, but you could pay as much as $10,000 for a high-end product.

Do your research and map out your space to help you narrow down the scope of your project.

2. Pick the Ideal Size and Location in Your Yard or Space

Swing and trees in backyard
Photo: Olga/Adobe Stock

Steps one and two go hand and hand, especially if you plan to buy a small outdoor greenhouse plan or kit instead of building a small greenhouse from scratch.

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 greenhouse plants will get the extra sunlight they need to stay alive.

Generally speaking, greenhouse kit sizes may look like this:

  • Small greenhouse kits are 6x8 feet space.

  • Medium-sized greenhouses creep up to the 8x8 and 12x8 feet.

  • Large can be as big as 24x12.

  • 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.

3. Decide Which Model of Greenhouse Is Right for You

There are common materials and even shapes that homeowners use to make greenhouses. You’ll need to decide which is right for you.

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.

4. Decide Which Covering You’ll Use for Your Greenhouse

Children playing inside greenhouse
Photo: Cavan Images/Getty Images

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.

5. Choose a Layout or Design One Yourself

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: 

  • Nineteen to 24 inches is ideal for walkway space. This way, you won’t bump into plants.

  • Benches or shelves should be limited to two or three feet, or whatever allows you easy access to all the plants in the space from one side. 

  • Two to three 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.

6. Build Your Greenhouse Floor

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).

7. Build Your Greenhouse Frame

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.

8. Install Greenhouse Covering

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.

9. (Optional) Install a Heating System

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.

DIY Small Greenhouse Build vs. Hiring a Pro

Man building greenhouse
Photo: Guido Mieth/Getty Images

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.

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