I’m so excited to show you how we built our new DIY cold frame garden beds with a super cool shou sugi ban (wood burned) finish.
I have wanted to try gardening for years but I worried deer would come through overnight and pick us clean – or my poor little plants would get hit by a sudden cold snap in May and perish. So when I heard about cold frames as a way to extend the growing season, I thought it would be great for us, not only because it’s so cold here and the summer so short, but because the lids would provide a little bit of protection from wildlife.
I shared some of the process of building these DIY cold frame garden beds on Instagram, but I didn’t share the tutorial right away because I ordered really cool hinges that automatically open the lids and they have taken weeks and weeks to arrive, argh. So I decided to finally just go ahead and share this cold frame tutorial today and share an update with those hinges later. Building these cold frames was so easy – the only tricky part was getting lumber! Apparently everyone in my city was building garden beds this spring, so cedar was sold out everywhere. But hubby found a lead on a local saw mill through a friend and we finally got us some 2″x6″x8′ rough hewn lumber for our DIY cold frame garden beds:
Supplies for DIY Cold Frame Garden Beds:
Here is everything we used to make these awesome DIY cold frame garden beds.
- 2″x6″x8′ rough hewn cedar boards (about 9 per box)
- 4’x8′ Lexan sheets (x 3)
- 3.5″ deck screws
- Straight edge
- Miter saw (or chop saw or jigsaw again)
- Table saw
- Propane torch (I bought this exact one)
- Propane tank
- Fire proof gloves (like those used for welding)
- Safety boots
- Shed pulls (x6)
- 6″ T-hinges (x6)
- 1″ screws and washers (plated or stainless)
- Tung oil and lint-free rags
- Medium duty chain
How to Build Garden Beds:
I’ll start with how to build the garden beds and then share the tutorial for how to wood burn them and build the lids. The actual garden bed boxes are super simple to build.
First we cut the boards for the four sides, using a sliding miter saw. To make it simple, the boxes are 4’x8′. We then cut the vertical support pieces to length from the same lumber and ran them through a table saw to cut them to width (approx 2″x2″). We pre-drilled holes and used deck screws (because they can withstand the elements) to put it all together. We found that assembling the front and back first was easier. So first we laid three boards on the ground, placed the vertical support pieces and screwed in all together – once the front and back “sides” we put together, it was easier to add the side boards one by one. Stand up a board and screw from the inside – that’s it. We did the sides board by board and it was super quick to put together. And affixing the garden box by screwing into the support pieces first, and then the wood boards, hid the screws from the outside, for a cleaner look. You could do it the other way too, and screw from the outside into the support pieces.
To create the slanted design, we took a board that was cut to length for the sides and divided it in half with a straight edge pencil line to make two triangles. Using a jigsaw we made the cut and then attached it to the bed.
Here’s a closer look at the construction of these DIY garden beds:
Ta da! Rasied garden beds. You can skip the slanted design for a simple garden bed without the lid. Or add more wood to make it taller. But this is the basic how-to for a DIY garden bed.
How to Shou Sugi Ban the Garden Beds:
I decided to use my favorite technique: shou sugi ban, for finishing the wood. Cedar is rot resistant naturally, but charring it adds even more weatherproofing to the wood. Plus, because the new house exterior is a dark grey/brown, the charred wood garden boxes blend in more and doesn’t stand out like the raw cedar wood.
For this wood burned project, I upgraded my tools and bought a 500,000 BTU propane torch. It’s AWESOME! You can char much more wood at a time than the smaller handheld propane torch I was using, which took awhile. This is far more effective for a larger project like this. (And way more fun).
I also wore my fire gear – but you don’t need it, lol! What happened was I decided I’d just use the boots from my gear and then I decided to see if my bunker gear still fits. My municipality finally sprang for my own custom turn out gear, but that was back in the winter and I had packed on the pounds since then, so I wanted to see if it fit so I’d be ready for calls this summer. It did! Barely. Once I had it on, I thought I should wear it for awhile because it’s so heavy and without regular training (due to social distancing requirements), I haven’t been keeping in shape and just wearing this gear is quite the workout. Luckily we also haven’t had many calls – I think the last time I wore this was sometime when there was snow on the ground. So I put it all on and wore it while I wood burned as a mini workout – you’d be fine in some coveralls, gloves and work boots. It DOES get hot (it’s fire!), so please DIY responsibly.
This gear HEAVY! I forgot how heavy. But I am so thrilled to finally have gear that fits. I no longer have to endure the question, “where’s the flood?”.
Charring the garden boxes is easy to do. First, bring the garden boxes to an area that is NOT flammable – stay away from grass. Gravel or concrete is safer. Then soak the nearby area with a hose so if an ember flies the area surrounding it is wet and less likely to catch fire. This has NEVER happened to me, but it’s better to be safe. Keep the hose nearby just in case. Treat it with the same safety you would a bonfire!
You can get better coverage if you char the wood before it’s assembled (otherwise it’s difficult to char between the boards) but this way is EASIER – you don’t need to handle the charred boards or prop them up anywhere. But it always looks better to char wood before it’s made into something. I just always go this route, charring something assembled, because it’s simpler and I like simple.
Once you have your own PPE (personal protective equipment) and have soaked the area, all you need to do is set up the propane torch and start charring! Work in sections and char really dark (it will lighten up). Basically, just burn it until it looks black! You don’t want to burn it though – you just want that surface level to looked charred. So don’t hold the flame on the wood endless, move it around and just char the surface. I pointed the torch at the wood and used sweeping motions to char and moved from spot to spot, working my way around and being careful not to char the hose or get too close to the propane tank with the flame. Once you’ve charred an area, the flame will disappear. It won’t light on fire! But if an area stays lit with a little flame, just give it a tiny spray of water. See more of my shou sugi ban experiments here and here.
Traditionally – and for indoor applications – I use a stiff plastic brush to remove the soot off, and char some more, and then brush again, and finally seal. That method, although labor intensive, creates a dark finish that won’t shed charred wood. But this is a garden bed! It won’t be touched as much and it will live outside where it will see rain and snow. So once I was done charring the whole bed, I soaked it with a garden hose to remove an loose bits. No brushing! Then the next day I charred any areas that still looked light. But I skipped the brushing!
I spread this over a few days because it was SO HOT in my fire gear, lol, but you could probably knock out building and charring all three garden boxes in a weekend. When the wood was charred, and hosed off, the DIY cold frame garden beds looked like this!
The cool thing about the wood burning is that it burned off the roughness. We would have had to pay extra for planed wood and because it’s a DIY garden bed we decided to buy the cheapest and rough hewn was really affordable. It had these rough little bits though, which I didn’t like, but all of that got totally burned off and the charring created a smooth, sliver-free finish which is an awesome benefit of this wood burning technique! I would rather burn than sand, that’s for sure!
How to Seal Shou Sugi Ban Garden Beds:
I wasn’t going to seal my shou sugi ban DIY cold frame garden beds, but people asked me if it was going to rub soot off if you touched it. After being in the rain and sun for weeks, there was very little soot even if I rubbed a shirt against the edge, but I decided to seal it anyway so I could test it out for people who really get in there and garden. I used an old t-shirt and rubbed tung oil over the outside sides and top edge (not the inside – no need). I used another clean rag to wipe off an excess. One coat of that and I can handle it now, although I don’t because the lids have handles and I don’t kneel on the ground and lean over (too scared of ticks) so I stand and bend over to reach any rogue weeds. But the tung oil sealed the charred wood beautifully and it’s all natural, so appropriate for a DIY garden bed – linseed oil is another option but it cures much more slowly and boiled linseed, although a quicker curing formula, contains small amount of lead. So tung oil, because it’s safe to use and cures quickly, seemed like a good choice and I have no complaints about it.
How to Position our DIY Cold Frame Garden Beds:
After soaking them with the hose, we left the DIY cold frame garden beds on the driveway overnight just in case there were an embers (again, an abundance of caution). In the meantime we marked where we wanted them to be and then dug up the sod. I made sure I left enough room between them to fit my lawnmower and enough space behind them (and my raspberry bushes) to pick berries and weed back there. I waffled about laying down landscape cloth and at first I wasn’t going to but underneath the sod is rock hard clay anyway so it’s nothing my plants could use. Se we laid down the landscape cloth to prevent grass and weeds from poking through.
Then I shoveled a 3/4 tonne truckload of topsoil. Every project requires I shovel something out of the back of my truck.
Unfortunately, even if we had wanted to we couldn’t leave our garden beds without lids, lol:
Look at that guilty face of Szuka’s. And Hynda was right in there too:
How to Make Cold Frame Garden Bed Lids:
For the lids, we knew they’d be heavy so we made two individual lids to make it easier to lift – and also for less weight for the hinges, which automatically raise a lid when the garden bed gets too hot. We created the frames using more of the cedar we bought, ripped into 2″x2″ boards and screwed together with deck screws. Then I charred them and sealed them, just like the garden boxes.
We chose Lexan for the lids because it’s safe to use in extreme cold exterior applications (won’t get brittle or discolor) and if a snow heap falls off the roof we won’t get broken glass everywhere, but you can also use old windows, etc. We cut the Lexan with a jigsaw to fit over the two lid frames we built for each box.
We screwed the Lexan on top, using 1″ screws and washers.
Then it was time to attach the hardware! We used these hinges to affix each lid to the garden box:
Finally, we added shed pulls for handles to each lid and some chain attached with screws and washers, so when the lids are open all the way they’re supported.
That way I can open them all up and water at once – or if it’s super hot, let them air out. I’m still getting the hang of the cold frame, but it will be awesome for extending the growing season here on Lake Superior! Here’s a look at our finished DIY cold frame garden beds…
The Finished DIY Cold Frame Garden Beds:
And here’s a peek at my little garden growing! It’s growing more and more each day but I’ll share what I planted – and what actually ends up growing – a little later.
I’m so excited that our DIY cold frame garden beds are finished! I got started a little late with planting my seeds this year but next year I’ll be all set and I hope to be able to garden a little later into the fall/winter – I’ll keep you posted! I don’t have a green thumb but I’m going to try.