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Thankfully, if you’re serious about the idea, and are willing to put in a bit of effort, learning how to build a DIY underground greenhouse is something anyone can do regardless of skill level.

Greenhouse gardening is one of the most preferred methods for growing fruits, vegetables, herbs, and even berry bushes, and dwarf fruit trees.

Greenhouses extend growing seasons from weeks or months longer to all year long.

In fact, with an underground greenhouse, you can grow various types of crops all year long no matter where you live.

Read on below and learn how to build your own DIY underground greenhouse!

6 Steps to Building a DIY Underground Greenhouse

Building a DIY underground greenhouse isn’t hard exactly, but it will take more work than setting up a basic DIY greenhouse or greenhouse kit.

In addition to all of the standard steps to setting up a greenhouse kit, or building a standard DIY greenhouse, DIY underground greenhouse constructions include a lot of digging, moving large amounts of materials in most cases, and extra finishing touches as well.

1. Measuring and Clearing the Space Above Ground

Clearing and measuring a dirt lot in the backyard for a DIY Underground Greenhouse.
Image/idea via plasticinehouse

The first step to building a DIY underground greenhouse is picking a great spot and measuring the space.

Make sure to choose a location that gets plenty of sunlight and doesn’t have flooding issues when it rains or snows.

Once you’ve picked a spot, mark the measurements for your underground greenhouse and then clean and level the ground.

2. Digging Down and Clearing Underground Space

A hole dug out of the back yard, to build a DIY underground greenhouse.
Image/idea via homeshalom

The second step, and one of the hardest, dirtiest, and most time-consuming is digging down into the ground and clearing underground space for your greenhouse.

Avoid digging in a location that has a lot of old tree roots, large rocks, or, of course, underground utilities like gas or water lines.

Picking a great (and safe) spot for your DIY underground greenhouse saves you a lot of time and effort.

3. Squaring Away the Inside and Reinforcing Walls

A diy underground greenhouse having it's walls reinforced and insulated.
Image/idea via ceresgs

The third step to building a DIY underground greenhouse is another messy one, but a little less backbreaking than the digging and hauling away dirt part.

Once you have a relatively complete hole for your underground greenhouse it’s time to square off the corners and walls.

It is also a great time to reinforce the walls with wood framing or with a tamper of some sort (compacting the dirt to strengthen it).

4. Building Stairs, Doorways, and Holes for Utilities

A white door and alluminum frame with clear windows and brick ramp and retainer walls leading into an underground greenhouse.
Image/idea via

The fourth step is an important one that requires a careful eye for detail as well as some forethought.

Your greenhouse, being underground, at least partially, needs stairs as well as at least one doorway.

It may also require some small openings for utilities like power cables or garden hoses.

If you have planned your DIY underground greenhouse properly, you already have a game plan for this part of the project.

5. Installing the Top/Ceiling of the Greenhouse

An underground greenhouse having tyvek paper installed on the inside and glass windows on top of a wooden frame.
Image/idea via offgridmaker

The fifth step of building your underground greenhouse is one of the most crucial.

How well you install the actual greenhouse on top of the hole you’ve created in the ground largely determines how well the entire structure will or will not work.

Installing a greenhouse kit over the top of the hole is the quickest, easiest, and surest way to get this step right.

But, if you are a skilled carpenter, you may opt for building a custom frame of wood, PVC pipes, or metal and covering it with glass, plastic, or some other suitable transparent material.

6. Clean Up, Installing Accessories, and Final Touches

A DIY underground greenhouse made from brick, wood, glass, and ceramic tiles.
Idea/image via

Before calling it done at this point, there are a few more things to take care like cleaning up your mess, setting up your greenhouse accessories (shelving, containers, and more) sanitizing the inside, and adding any other final touches you desire.

This final step includes adding paint, trim, stacking bales of hay around the structure, and any aesthetical touches you want your DIY underground greenhouse to have.

Final Thoughts About Building a DIY Underground Greenhouse

Following the six steps above, anyone can build a functioning DIY underground greenhouse.

Just keep in mind that if you opt for a semi-underground greenhouse (one that is less than 6 feet deep), rather than one that is fully underground (5 to 10 feet deep, at least), there is no guarantee that it will extend your gardening seasons through the entire year.

The amount of work it takes to build a DIY underground greenhouse is far more than building a normal greenhouse.

So, think hard and long about it before you make a decision about whether an underground greenhouse is right for you (or worth it for you).

Do you have an underground greenhouse? If so, how did you build it? Let us know how helpful our guide is/was!

Thank you for reading, and good luck with building your new DIY underground greenhouse.

Suggested Reading: Best Cheap and Easy Greenhouse Kits (Our Top 4 Picks)

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