Compost Bin, Then a Raised Bed?

July 2, 2019 11:05 AM

Naivete has led me from a small scale upcycling project to feeling like I have inadvertently mounted a hobby horse that is not my own and am in danger of being thrown. Can I make a wooden box I cobbled together into a compost bin and maybe later a raised bed garden?

The neighbors were throwing away some wood from an old playhouse. Comrade Doll thought maybe we could cobble a compost bin together out of it. We didn't really do any research. We just cleaned up the wood and built a box. It's about 24"h by 48"w x 48"l. Having done a bit of pressure washing and sanding first, it looks surprisingly decent. But we never really had a plan for optimum composting beyond "Let's throw food scraps and lawn clippings there on the far side of the yard." We figured to line it somehow, but weren't clear on best practices.

CD would now like to make it into a compost bin for this year, then, at the end of the season, mix it all up with nice soil and fertilizer, then use it as a raised bed next year.

Can we do that? Would that plan necessitate different steps than a compost bin?

What kind of lining do we need?

posted by DirtyOldTown to Home & Garden (9 answers total)

So the ideal conditions for composting -- for things to form a pile -- aren't necessarily the best conditions for a raised bed, which is lower and wider. But slow composting can also work if you just let things pile up and then turn it over once in a while (you have to stop adding to it at some point). It's also not that hard to move compost if you don't have that much of it (and it loses a lot of mass as it breaks down). You don't really need a container for composting, so I think you could probably still go with your pile-things-over-there plan for grass and food scraps.

Also, it seems to me that you'd want different locations for a compost pile (ugly) and a raised bed (attractive). Also, if you're going to grow veggies or flowers or things that need sun in your raised bed, that might not be where you'd put your compost.

Are you thinking of lining the bottom? The thing is that you want the microbes and bugs in the soil to get into the food scraps and clippings to make the compost magic happen. So why the lining? If you want to discourage grass or something, then you can put down a layer of paper bags or newspapers, but it's not necessary.

This is how I might approach this: figure out where I want to put that nice raised bed structure and put it there. Maybe get some dirt and add it and put some flowers or late season veggies in (if I was going to do this right away). It would also be fine to put the structure where you want it and just let it sit empty. Then, I'd keep doing the composting on the far side of the yard (or wherever). You can get a plastic Earth Machine type compost container, but you don't really need it (though sometimes cities sell them for cheap to encourage you to compost). But, I'd probably just let things pile up and maybe turn them once in a while (mostly because it's cool to see how things decompose).

Having said all that... sure, you can absolutely compost in this thing. It'll probably be slow, and you might not get that much compost out of it. But it could be an easy, slow compost project if you want. But I wouldn't line it.
posted by bluedaisy at 11:22 AM on July 2, 2019 [1 favorite]

You can compost in anything, though if you want to grow food (rather than ornamental plants) in it you should be not in anything that leeches toxic chemicals, which pressure-treated wood might do. I assume that's why you're asking about a liner.

Something I'll warn about, though: it's real hard to compost in the open unless you are very comfortable with the local vermin treating you like a Golden Corral, possibly one with a Motel 6 next door as they move into your attic to live near the goodies.

My suggestion would be to build your raised bed, also set up a closed bin or tumbling composter wherever a good place for that to live might be (tip: part of your property farthest from anyone's roofline) but not IN the bed because you'll want to use that space later.
posted by Lyn Never at 11:24 AM on July 2, 2019 [5 favorites]

Is this wood painted? I might want a lining if so, probably some black landscape cloth at least, more depending on your risk tolerance / exact situation. Might also be a good idea to cover the bottom and around edges if you're putting it over an area that currently has turf - you will probably want to do additional grass-murdering steps as well (e.g. cut turf chunks and turn them root-side up, cover with cardboard and/or newspaper sections).

24" is going to be a pretty low/small pile and probably won't compost very fast or get up to high temps. I wouldn't count on the compost being ready in the fall.
posted by momus_window at 11:32 AM on July 2, 2019 [1 favorite]

For a compost bin you'll want to line it with hardware cloth on all sides, even the bottom. "Hardware cloth" is not cloth at all but more like a 1/2" wire screen/fencing. Otherwise it'll be a rat and mouse hotel.

Depending on what you throw in it's not likely to be very composted in a single year. It's possible but my "eh, do whatever" compost took a few years to turn into proper compost. Also, it turns out certain seeds are very durable and you're likely to get a few stray zucchini popping up. But sure, given some time and some additional soil or municipal compost, you could probably make it into a raised bed.
posted by GuyZero at 1:02 PM on July 2, 2019

Yes, this is exactly what I (and others) do. We choose one raised bed to be the compost bin for the year and rotate. If there is uncomposted stuff on top when we switch, we just pitchfork it into the new one. If stuff is attracting flies, just throw a shovel of dirt on top. So, use it this year, and build a new one next year, this way you get a new raised bed each year (until you have enough).
posted by 445supermag at 1:05 PM on July 2, 2019 [4 favorites]

Yes, what 445supermag said is what we do sometimes too. Just throw all compost into an empty raised bed for a year and then put good soil on top and plant it up. So you could do exactly what you said in your post. What you really don't want to do is have any uncomposted animal manure in there if you're planting food plants in the bed. If all you put in your compost is plant scraps and grass clippings (no pesticides or herbacides on those clippings right?) you'll be fine. Keep in mind that the level of the soil in the bed may drop a bit as compost continues to biodegrade.

Unless you live in a dry, desert area it's not necessary and not even advisable to line a compost bin. Oxygen needs to be available for the composting process to take place. Here in New Mexico it's so dry, that most of us do line our bins with plastic liner, but then it's necessary to add bulking material like pine cones or big sticks to keep pockets of oxygen in our bins. If the lumber that you made the box out of is treated or painted, I would not compost in it or grow any plants for food in it at all.

Composting practices will vary a lot depending on the climate where you live. Your county extension office will likely be a good resource for you if you have questions. Many have master composter programs if you want to take your compost up a notch. I did it and I recommend it!

Lastly, thank you for composting! You're saving the earth, you really are. While you're at it, don't forget to do your research and plant some native plants that feed your local bees and other insects throughout the summer and fall.
posted by WalkerWestridge at 1:33 PM on July 2, 2019 [4 favorites]

I live in the SE Arizona scrub desert, so things are a bit different. You have to commit to watering a lot in order to grow anything. I'm new here, a native of Missouri and Illinois, but I've watched an Arizona native, a neighbor, as he prepares beds. He'll dig out an area, about a foot deep and the size of a sheet of plywood, and pile organic debris in there, mesquite branches and whatever else he can find. He'll top the pile with the dirt he had dug out and water it. The following year he'll plant vegetable seeds in the bed. A lot of work, but he does get good yields. I second the comments about screening your piles from rodents, etc. Around here rock squirrels and kangaroo rats will consume everything you put out unless they are fenced away.
posted by Agave at 2:00 PM on July 2, 2019 [1 favorite]

You could be able to combine them in a keyhole compost-garden bed. You would put that in a good sunny gardening spot. I would sure think about how to ratproof the center compost basket. (Heavy small-scale wire fencing, probably, but it will last not so long when buried in active compost.)

But definitely, check with local gardeners and Extension for local practices.
posted by clew at 5:16 PM on July 2, 2019 [1 favorite]

I started a raised bed garden by putting down a couple inches of clean cardboard and newspaper the fall before, topped with lots of leaves, then soil and bagged composted manure. It takes a lot of cardboard and newspaper; I scoured the recycling on my street. It smothers the grass and weeds and composts itself. Oak leaves are acid, so I sweetened it up with some ashes from the wood stove, also a good source of potassium. Post on freecycle.net; someone will have wood ashes. Put your wood box in a sunny spot, get lots of compostables, get going. Leaves, cardboard, etc., really compost down,so you will need a lot of material and then a fair amount of soil to add

I am a lazy composter. Who wants to turn compost? What's the rush? I've learned that leaves form a mat and may inhibit air flow, but they will break down. Citrus rinds can putrefy in a mat of leaves; I no longer compost citrus. 25+ years and I still remember that aroma. I pay no attention to green or brown and trying to achieve an unlikely balance. Vegetation? Compost it.

No animal products, they will really attract critters. The compost may attract raccoons, who can carry rabies but are fun to watch from a distance. No rats in my area, pretty sure the garden snake deals with mice; we have a truce. I usually cover food waste with leaves. Dog shit requires high temp to be safe; I used to throw it on a bed that had increasingly lovely day lilies and irises but no food crops.

There will be a Cooperative Extension Office not too far from you;they are really helpful. Home-grown tomatoes are the best. The initial investment is real, but you an keep gardening for years.
posted by theora55 at 6:23 PM on July 2, 2019 [2 favorites]