Building a raised bed garden planter

Originally published at: Building a raised bed garden planter | Boing Boing


My local corporative extension has a lot information on raised beds with advice from people experienced using them in my climate. For example, here if you make them over 18 inches tall, they tend to dry out too fast.

I speculate that in more humid places you may need to use wood that is pressure treated for ground contact

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Yeah, I don’t really understand raised beds, specifically walled box beds. They’re a lot of infrastructure without a clear advantage. If you need better soil tilth, you can amend nearly any soil or just make raised piles (basically raised beds without the boxes). A lot of raised beds I see are really tall and besides drying out really quickly, require a shit-ton of soil to backfill. That isn’t really an ideal environment as it’s one type of highly compactible soil with no structure and will eventually just settle into a brittle, dry cake. With bed piles you are a) amending the soil that already exists (this is especially important if you have a non-permeable soil which is not going to get better by setting a box on top of it; working in new organic matter is what it needs) b) building tilth year-over-year and c) are able to apply amendments in the easiest possible manner (every year add compost, work it in, then mulch; repeat every spring). If you properly mulch them, your beds will be virtually weed-free (assuming your compost was properly done). I think people need to see structure to feel like they’re conquering nature or something, but in reality it’s creating unnecessary headaches (see also: lawns that no one really uses).

And just to dispel any ideas that without boxes, you will just end up with a chaotic mess, this is a photo from our friends’ BnB showing how lush and refined it can look with basic care. Their recipe after establishing them is basically: add 2-4” of compost and mulch every spring. The mulch from previous years helps with aeration and structure while the compost accommodates any depletion. Oh, and planting directly into the ground allows all of those wonderful creatures like worms and burrowing insects to create even more tilth and aeration instead of being dead dirt in a box.

ETA: forgot photo:


Yes, exactly. Most places in the US need PT wood or very expensive rot-proof woods like cedar or locust. Even then, you’re still fighting entropy year over year and even the best construction will start sagging and collapsing with that much organic matter piled up next to the wood. Of course, you can line it all in plastic (bleccch!).


Where I am, it was the easiest way to get started. Nothing like the video, I just slapped some untreated 2x12 s into a rectangle and filled with soil. Our ground was just impossible to work by hand when we bought the place (very compacted and very rocky) so that let me have a little garden without breaking my back.

It worked out well, though, because 10 years later the wood is on its last legs but now the soil is good and I can just transition to a mound thing like you mention.

The ones in the video look pretty, but I would need a big ladder to harvest a bunch of the stuff I grow. Unless he plans to make the trellis also be climbable, which would be kind of cool.



They’re great if the soil underneath is sandy or has a lot of clay, and it would be way too difficult to amend that soil.

But they’re especially good if you want a lot of mint, but don’t want it to “escape.”


Be careful, though. I’ve seen plenty of raised beds built to contain mint family plants that end up being a series of nothing but mint boxes. Unless they’re completely sealed off, life… uh, finds a way. Fortunately, the more “useful” mints don’t seem to be as aggressive as lemon balm and shiso. Those guys will take over an entire garden if they’re not constantly checked.

Even if you’re going to use raised beds, double digging is a great way to start a bed in poor soil, especially clay. It’s a decent amount of work (but not excessive unless you’re growing large crops), but it’s also a one-time deal. If I was going to use raised beds, I’d still want to break up, aerate and add organic matter (and sand for clay) to it before putting the boxes up. Otherwise it’s basically sitting on concrete and even a smaller annual’s roots will want to go deeper than the bed walls. If you add plants with deeper taproots, they will help draw beneficial soil critters into the lower horizons and draw nutrients deeper into the soil.


Never tried it myself, but I’ve read that planting daikon radishes is a great way to break up hard pan.

As you said, nature finds a way!


Most pressure-treated wood is soaked in chemicals that you might not want to be eating. That’s even the case with the newer treatments.

Use cedar instead, or just replace the boards every few years.

Indeed, keep mint in its own pot. One or two square feet provides all the mint you need unless you’re making mojitos for everyone every night.


Yeah, I’ve had friends plant mint and things like rosemary (which doesn’t overwinter well here) into pots that they bury up to the rim in spring and take inside in the autumn. I wouldn’t do it with terra cotta as it would end up cracking and rotting, though. It’s also a good technique for large planters that dry out easily. I buried the bottom few inches of a planter once and it held moisture for much longer than when it was on a tray. I’ve also seen people use thick terra cotta pipes to prevent roots traveling, but that’s more of a permanent placement and in reality, they often just leap over the top.


We live on clay. Extremely dense. We have several beds unraised beds with amended soil (lined with stones) but one big raised bed for the majority of the garden veg. Tomatoes do not do well in the unraised beds. Amending the soil deep enough just makes a gigantic mud puddle. The water will just sit in the hole with amended soil and take a long time to disperse into the surrounding clay. Hello root rot. We plant other things that can handle the clay in the unraised beds, like natives, a special kind of blackberry, some kinds of roses.
The surrounding stones keep the dirt in and the aggressive pre-existing grass out. We turn and amend the bed every year. Yes, it took a ton of dirt to fill. It doesn’t seem to dry out any faster than anywhere else and we ran drip irrigation. Harvesting and hand control of pests is easier too.

The piles in the pic are really pretty. But a lot of that soil would run off in the kind of spring rain we typically get and keeping the grass out would be a full time gig.


We did this as well, lined with root-blocking fabric, because we live in a city and there is lead in the soil. I think that’s another fair reason to do raised beds (our unraised bad took a lot of digging).


Block is a million times better than wood. I guess that’s the type of raised bed I’d install if I had extremely heavy clay. It also helps regulate temps and evaporation on really hot days. You can probably soak them in the morning and they’ll act like a heat sink all day. Looks like you installed drains in the bottom, too. That’s got to be critical if you’ve got no soil drainage.


Last year, during the pandemic, I was lucky enough to be working with a small group designing and building a whole raised bed community garden in New Westminster, BC. The advantage of raised beds is two fold:

One, the land was previously slated to be a gas station - that was never built, then a construction site - and basically, the soil was not soil, mostly hard pack , giant boulders and as as we learned, construction debris. (We literally had to dig 4x4 trenches and fill it with proper soil in order to plant rows of trees because there was no soil for them. This was an unexpected expense.)

Two: Architecture. Raised benches help with pests and provide a place for people to sit. Quite a lot of people have trouble working on the ground. Raising the box up helps with that. We also build a standing box that was about 3 feet up so you don’t have to bend over at all. And a wheelchair accessible box.

The boxes where special though, not your typical box of dirt. These have a tile system inside that creates a reservoir in the bottom. So you can fill it up and it will slowly wick the moisture up into the soil, which is a mix of compost, soil and vermiculite. You need this mixture, unfortunately, or the water won’t wick well.

It wasn’t all boxes though. My wife volunteers with the CHTA ( and it was important to her that we actually did have some actual living earth on the site. To that end we made an indigenous plant garden. A sort of island in the gravel that we dug down into all the way to the natural soil and completely rebuilt with compost and soil and logs. We then replanted it with native food plants that live in BC.

I haven’t been to visit this spring yet, but they handled last year’s heat-dome quite well. This year a local community garden group has taken control over it and we’ll see how it goes.

The boxes planted:

The place when we arrived had nice looking dirt and gravel… but it needed work:

The natural garden area, before we had anything planted.

If you’re interested, learn more here: Ryall Park Community Garden


I realize that I’m in a challenging biome but I sure wish I had those “problems.” The extreme heat and number of days of it, drought (we just went into la Niña and it’s already very dry here), and crashed soil biology here in my patch of central Texas will reliably murder every plant you listed, unless I put shade cloth over them or plant in heavy shade.

Whatever the heat doesn’t kill, the deer will browse out (yes, even the mints, all aromatics but for–)

(which the deer do not eat and grows like a weed here, until ice storms kill them)

All this said, here’s the only thing that I have found that works, for semi-arid, hot areas:

(I used livestock troughs, and scoria = lava rock AFAICT)

reporting from Zone 8b
~900feet altitude
atop the Edwards Plateau (limestone, often at grade)
29°F a few nights ago, today will be 80°F

I got my first 2022 fire ant bites yesterday.
Spring must be here. It’ll be over in a week.


Yeah, my partner did most of the work. Dug a trench, lined with paving sand. Placed the blocks. Then dug into the inside to break up the clay. Installed french drains. Then filled it up with a mix of compost, clay we dug out, commercial garden soil, peat, some mulch. Mixed it all as we went. We had to add more the next year, as what we had settled. Changed an entire section of the sprinkler irrigation to drip and ran piping every where. It was a lot of work and a lot of money. But it looks nice, the drip irrigation works really well keeping everything hydrated without encouraging fungus on the plants. Bonus home for some wild bunnies (they kept ripping the caps off the drains until we gave up!). I’ve noticed a major uptick in earthworms nearby in the yard too.


That’s beautiful. As you and @SamSam point out, raised beds are great for reclaimed/urban spaces where someone may have already spoiled it. And accessibility is a must for community gardens.

I made a similarly-designed set of buckets a few years ago with a reservoir and hemp wick. It worked really well to keep the soil ■■■■■.

My mom lives in NE Oklahoma and despite all of my efforts, she can’t get anything to grow. Maybe if I had more time, but she’s elderly and it would take years to get that soil to a useful place without equipment.

Maybe they’ll keep it cleaner? :man_shrugging:t2::crossed_fingers:


That is an impressive project and I love the design of the natural planting!
We plant a lot of natives to support the local insect life

@j9c the drip irrigation is the only way we get thru the summer. Even then, most of the plants die back in August. Too hot for pollen then too. The tomatoes typically recover enough for some more fruit in the fall. The roses I have seem to love the heat, wierdos.


Yeah, I have a 4’x4’ box that’s just mint. And one that’s just herbs.

When I had a larger garden (around 7k sq feet) we’d move the chickens around for them to scratch and fertilize. That worked great for soil amendment. Now we live in a smaller piece of land, so we don’t grow as many of our own veggies.


It also saves a ridiculous amount of water. Sprinklers can lose 30% or more in a humid climate.


With the price of lumber right now and depending on the size one might need, large galvanized fire rings or feeding troughs from a farm store are cheaper and faster to get up and running.

A deck that we’ve been planning since the before times has tripled in price for the wood. We’re just doing it this spring because it looks there will be no relief for at least another year.

There are even raised beds with no bottoms available on Amazon but those require a lot of screws to put together because they get shipped flat.