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Want to find out how to build a greenhouse cheap? This guide is full of great tips for constructing your own greenhouse on a budget!
A DIY vegetable greenhouse is a great way to extend your growing season. You could even possibly grow vegetables year-round if you ensure your little greenhouse is heated through the cold months.
Since we live in a fairly cold climate, we NEED to grow tomatoes and peppers under covers and a greenhouse works perfectly for us. Although we can’t grow enough tomatoes to preserve a lot of tomato sauce, we can fit enough plants in here for fresh eating.
There’s nothing better than picking cherry tomatoes right off the vine and popping them into my mouth!
How to Build a Greenhouse Cheap (Outdoor Greenhouse DIY)
DIY greenhouses are surprisingly affordable and offer lots of options. Our greenhouse is unheated and it’s usually used from April to October.
And we’ve outlined just how we built it below, to give you some free greenhouse plans that will work for you! But first, here’s some general important greenhouse information you should know.
Is it cheaper to build a greenhouse?
In our case, yes it was definitely a LOT cheaper to build our DIY home greenhouse instead of buying a full greenhouse kit. Keep reading to see exactly how we built ours for some greenhouse ideas for your yard!
What is the best direction for a greenhouse to face?
Try to site your greenhouse so it faces south or southeast. This holds true if you live anywhere in the Northern Hemisphere. The reason for this is to allow as much possible sunlight in, which is especially important of course in the winter months.
Siting your structure properly will allow that winter sun in, even in January and February.
Do I need a permit to build a greenhouse in my yard?
Well, that all depends on where you live. Many areas do require a building permit for any structure over a certain amount of square feet.
Call your local town office and speak to the building department. It could be you don’t even need one, or it could be that the finished project can only be 10 x 10.
You won’t know unless you just ask how big a backyard garden shed or greenhouse can be before you need to apply for a permit.
What is a Cold Frame Greenhouse?
Cold frame describes a clear and insulated outdoor structure that can be used to shelter plants during the colder months. Instead of using gas or electric heaters, a cold frame garden depends on light from the sun to create solar heat.
They’re great for creating a more consistent environment, especially if you live in a climate where the weather can be unpredictable.
This kind of greenhouse allows you to start planting earlier and harvest later without having to worry about frosts, sudden dips in temperature, storms, or any other unexpected obstacles that gardening in colder weather may bring.
Cold frame greenhouses will typically offer a space that’s 5 to 10 degrees warmer than the temperature outside but also offer options for ventilation.
A cold frame garden is also a great option for transitioning any herbs or seedlings that may have been planted indoors but now have to come outdoors.
The environment it offers is stable and more controlled, which will allow your plants to adjust to the outdoors. They can then be transitioned to another garden, transplanted in grow bags for your patio or deck, or left in the greenhouse.
Here’s How to Build a Greenhouse
You already know that a greenhouse is a fantastic addition to any home and it can be built cheaper than you think.
We built ours stick frame but you can easily build hoop greenhouses, which would be less trouble constructing than the one we built.
Ours is very durable however and we are glad we went with stick frame. Our winters are severe enough here we need a steep roof on the greenhouse, so the winter snows will slide off.
Since hoop houses don’t shed the snow as easily, we thought it was best to go with the steeper roof.
Temporary Greenhouse ( One Season)
The picture above is a temporary greenhouse that Graham made soon after we moved here. That year, we grew squash, beans and cucumbers under that cover.
For the permanent greenhouse plans, Graham wanted to reuse those roof panels that you see in the picture.
The roof panels were in two pieces. When it came to deciding where to site the permanent greenhouse, we had some thinking to do.
In the end, we decided to build the new greenhouse right on top of the oldest compost pile. Why create extra work for ourselves?
This way it would be easy to rake out, take away the excess, and leave some really awesome soil underneath the plants.
Right next to the site, we had a second pile of well composted manure. Nice and easy to move into the new greenhouse!
DIY Cheap Wood Greenhouse Equipment List
You’re obviously going to need the very basic tools to build a greenhouse, such as:
- hammer
- tape measure
- nails
- screwdriver and bits
- drill
- screws and bolts
- brackets, if needed and other hardware
But there are additional tools that you will need, or at the very least will make this backyard project a lot easier. These include:
- a miter saw
- a circular saw
- greenhouse plastic
DIY Greenhouse Lumber List
Use this list to estimate your lumber costs, depending on the size of greenhouse. Ours is 12 feet long.
Your costs will vary, of course, depending on the finished size and lumber costs in your area.
- 4 – 12 foot 2×4
- 16 – 8 foot 2×4
- 6 – 12 foot 2×2 (for roof panel)
- 1 roll polyethylene sheeting
- staples, nails, screws & the rest of the obvious!
Building a DIY Vegetable Greenhouse
First, we framed up the one wall.
Then another and another and voila. The basic frame was ready.
Next, we worked on framing in the walls.
Can you see where we laid logs inside where we needed to level the site out? You know why logs are good? Because they are FREE.
Then I started raking smooth all the compost and also adding the great soil from the pile in the back. The compost that wasn’t quite ready, I just shoveled onto the other compost pile. Siting the greenhouse right here was a LOT less work in the end.
Of course, we had put the piles in a good spot to begin with! Nice and close to the garden and far enough to the edge of the lawn that they weren’t under the trees.
You can really see the lay of the land we were working with. See the slope? And that middle hump inside the greenhouse is the left over pile of finished compost.
Over time, I raked that over to the edges to fill out the raised beds inside.
Here’s a better picture of the log details.
Once that was done, we started working on putting the roof panels in place. Graham added a ridge beam from timber we had here, then attached the panels to that.
Graham put a great pitch on the roof and it should hopefully be able to withstand all the snow in the winter.
Adding Plastic Poly to DIY Greenhouse Roof and Walls
Later, we stapled the plastic poly around the sides. We stapled it very well, so the wind couldn’t catch the plastic sheeting and start lifting it off.
For the greenhouse covering, , instead of buying the special plastic, we just used 6mm plastic off a roll that we had laying around for a building project. Some people prefer to get greenhouse weight plastic.
Since the bottom areas of the front had open spaces, I played around with building rock faces on either side. Easy and FREE!
And here’s what it looks like from the porch – we are very happy with the way it turned out. It was a fair bit of work, but it will add a LOT to our homestead. And no tutorials or instructables were necessary; the structure was simple and easy to put together!
This greenhouse project has enabled us to grow peppers and tomatoes. If you live in a northern climate, you really can’t go wrong building a backyard greenhouse.
Using basic tools, you save a lot of money building your own, as opposed to buying a new greenhouse.
Build your own greenhouse for about $300, including electricity – extend your growing season, start your own seeds and grow your own organic food!
The cost for ours was well under $200, even if we would have had to buy that roll of greenhouse weight plastic.
What if the Greenhouse gets too hot?
Sometimes, in the heat of the summer sun, it does get really hot in the greenhouse, even though we have there is no plastic up close to the gables. You can see that in the photo.
If this happens with your greenhouse, you have a couple of choices, one being to install a greenhouse fan. Even if your greenhouse doesn’t have electricity, you could always run an extension cord from the outside of the house and run a fan.
You can also install greenhouse vents, the automatic vents make the most sense, because you don’t even need to be there to open and close them.
Or check out these solar greenhouse vents and fans!
What we do though, is we water the greenhouse – on the outside! I just hose down the clear roof and walls from the outside. If you do this, make sure your hose has been sitting in the shade.
Or, run the house for awhile so all the hot water inside it runs out. You don’t want to be adding hot water from a sun baked hose to the already hot greenhouse.
I spray it down a few times a day in the heat of summer and it helps a lot.
Other Ways to Build a Greenhouse
There are a number of other materials you can employ when putting together your DIY greenhouse plans.
PVC pipe is a fairly inexpensive material, and the piping is especially great for a mini greenhouse, for adding internal structure, or for cold frame gardening.
If you’re particularly handy, sometimes old windows can be upcycled and used in your greenhouse. This may also be more easy to work with on a smaller scale. Here’s a beautiful greenhouse made from old windows.
Build a CD case greenhouse! Believe it or not, CD cases can also be helpful for planting. Making a small greenhouse out of the plastic cases is a great way to repurpose them if you have CDs lying around that you’re no longer using.
You can also buy CD cases in large quantities. The sturdy plastic is a reliable material for planting, and would be great for DIY cold frames.
Plastic bottles in excess can make a fantastic outer shell for a greenhouse. Check out this guide for more detailed instructions on making a plastic bottle greenhouse.
More Articles about Growing in a Greenhouse
- Here’s how we get the Greenhouse ready for the growing season (Spring maintenance tips)
- Find out why I always transplant tomato plants before planting them again into the greenhouse.
- Ever wondered just how small of a pot is needed to grow peppers that actually set peppers?
- Want to read all our posts about growing in a greenhouse?
originally published 2017; latest update Dec 2024