Timber Frame Swing Set Repurposed Into An Awesome Underground Greenhouse


Nadine and James Buchanan purchased a home in the Slocan Valley, the heart of the Kootenay Range in British Columbia. They thought it had good potential inside with several sustainable living features including an in-floor heating system running off the woodstove and a propane backup, as well as a few other nice touches.

The property was only 1.7 acres but nicely wooded along the edges for privacy and cleared mostly for food production on the interior. According to James, the previous owners were pretty standard gardeners and they were happy to take what they had started and transform it to the next phase.

Among those ‘next phase’ ideas was a project they are still refining to this day. When they moved in, they found a timber frame swing set that was located adjacent to one garden in the back. Since they realized their swinging days were over some time ago, James decided to make an underground greenhouse out of it for Nadine….

An underground greenhouse is partially buried in the earth and has a transparent (usually plastic) covering that stays warm by passively soaking up the sun’s heat but also by absorbing the earth’s thermal energy. This means that the temperature inside stays largely consistent regardless of the weather outside, particularly in the cooler months.

That also means that fruits and vegetables can be grown year-round, making an underground green house ideal for communities in colder locations that can’t usually grow their own fresh and local produce during certain parts of the year.

James & Nadine’s underground greenhouse measures 12′ x 21′ and features a passive heating system in the winter, programmed lighting, irrigation, and misting to cool in the summer months…

A squirrel-cage fan is used in conjunction with the misting system to keep temperatures from soaring when the sun is directly overhead…

James started the project by excavating 3′ down to provide a more stable temperature, and to provide some needed headroom. Since the property is on an ancient creek bed, there were plenty of rocks to be removed.

These were set aside and once the layout was plotted, they replaced the rocks into the bottom of the beds along with some vented tile that connects to an inline fan and a similar vented tile running along the ceiling…

During the cooler months, daytime heating that collects in the peak of the ceiling is drawn through the system and blown into the rock beds below for passive heating at night…

This impressive little greenhouse is therefore able to maintain between 6 to 10 Degrees Celsius warmer temperatures than the outside temperature during the winter months…

Nadine is able to grow & maintain many of the heartier crops throughout the winter, including kale, spinach, and beet greens. James says that living in a 5a – 5b growing zone where they haven’t seen 20 below in a few years makes growing throughout the winter very ‘do-able’…

This project is a beautiful example of repurposing something that might have otherwise simply been cut up into firewood into something extremely practical. Now this cleaver couple are able to grow year round and supply themselves with their own fresh veggies & produce.

What do you think about this project? Have you repurposed anything else into a tidy little greenhouse?


Love it. Are there any plans?


No, unfortunately not.

I guess it would all depend on what you’re starting with in terms of the initial wooden structure (i.e. the swing set).


I have an old timber swing set that the swings have broken off so I’m going to use this great idea thankyou


Wow, that is a huge project with an awesome result. Well done!!


So cool. I’m considering this subterrainian type greenhouse and this one seems the easiest so far.


Yeah it’s nicely done.