Can I place compost on top of wood chips around my raspberry bushes?

October 1, 2020 8:34 AM

I have a raspberry patch with about 100 bushes. Last year, I placed wood chips throughout the patch, including around all the bushes. Presently, the layer is about 1 to 2 inches thick. Is it OK to place compost on top of the wood chips around my bushes? I couldn't find an answer to my question on the Internet.
posted by kirsti to Home & Garden (17 answers total)

Best answer: It's OK to put compost on top of damn near anything damn near anywhere. The only thing you need to be a bit careful about is not piling it up around on the stems of things, because doing that can sometimes keep stems damper than they should be and promote rot in the bark.

The ideal place for compost would be underneath the woodchip mulch: as woodchip breaks down it will be steal a little nitrogen from the topsoil underneath, nitrogen that would otherwise be available to your raspberry plants for making foliage out of, and the compost would offset most of that. But disturbing an existing layer of woodchip in order to get your compost underneath it is not worth the effort, especially given how prickly raspberry bushes are. If you just scatter your compost on top of the woodchip layer, you'll find that it will pretty quickly gravitate to the underneath anyway with a bit of help from watering and worms.
posted by flabdablet at 8:48 AM on October 1, 2020 [6 favorites]

It won't do any harm, but to help your plants, compost needs to be mixed into the soil. You don't need to dig the plant up or anything, just move the mulch aside, put compost around the plant (picture where the roots would be rather than the stem/trunk) and work it into the first inch or two of soil. Rain will take over after that.
posted by headnsouth at 8:49 AM on October 1, 2020

This is a good question. My instinct tells me you should rake back the mulch, and then apply the compost, and then re-rake the mulch.

I don't think it will hurt the plants, and like flabdablet said [on preview] keep any organic matter away from stems.

Also, for gardening questions, check out the local state Master Gardeners group. They are there to answer questions and do research if they don't have an answer.
posted by terrapin at 8:50 AM on October 1, 2020 [1 favorite]

to help your plants, compost needs to be mixed into the soil

Absolutely true. Also true that you don't actually need to do the mixing yourself, because compost will pretty quickly attract enough earthworms to do it for you.
posted by flabdablet at 8:51 AM on October 1, 2020 [8 favorites]

Also also, if that woodchip layer has been in place for a year, you're going to have quite a lot of useful fungi living in amongst it now - fungi that on balance you're probably better off not tearing into pieces by mechanically disturbing the woodchip. Just let the earthworms do it. Their touch is more delicate than that of your rakes or trowels.
posted by flabdablet at 8:57 AM on October 1, 2020 [5 favorites]

I would rake back the chips, spread compost, and re-spread the chips because otherwise I’d lose the benefits of the top side of the chip blanket (insulation, weed-unfriendly). The compost is likely to start the chips rotting as it migrates through, and then you have lovely bare soil instead.

OR put on enough compost to consume the current chips and then a new layer of chips.
posted by clew at 9:00 AM on October 1, 2020 [4 favorites]

I agree with clew's second suggestion. I don't believe it's possible to add too much mulch.
posted by flabdablet at 9:03 AM on October 1, 2020

If you’re water-limited and above freezing you’d eventually be using irrigation to support decomposition that would go all the way to atmospheric CO2 instead of SOM. Or with low soil activity you’d just get a pile of mulch. But in most gardening climates, true.
posted by clew at 9:21 AM on October 1, 2020

I agree with clew's suggestion to add more compost and then another layer of chips. As flabdablet says, you don't want to disturb the mycelium and fungi networks that currently exist.
posted by Lexica at 9:22 AM on October 1, 2020

If it wasn't raspberries, I'd pull back the old chips, put down the compost, and pull the chips back over, but I don't hate the skin on my hands/arms/face that much. Compost over chips, maybe fresh chips over for water retention if you've got some.
posted by Lyn Never at 10:23 AM on October 1, 2020

You could use a compost tea.
posted by spitbull at 11:17 AM on October 1, 2020 [1 favorite]

to help your plants, compost needs to be mixed into the soil

If that were true, compost tea wouldn't be a thing.
posted by HotToddy at 11:43 AM on October 1, 2020 [1 favorite]

I also vote for compost over chips, add more chips on top. As long as you've got the chips, it's less work for you, and at worst, just a little extra time to achieve the same result.
posted by ivan ivanych samovar at 12:36 PM on October 1, 2020

Best answer: Compost on top of wood chip will break down further and nourish the soil, maybe not as promptly, but I always find roots reaching up into the compost heap (unless I use a barrier) and grabbing the stuff. The compost should help the wood chips decompose a bit faster. In theory, as the wood decays, it can steal nitrogen, releasing it later. Make a point of peeing in the raspberry patch. /slightly sarcastic, not entirely
posted by theora55 at 1:05 PM on October 1, 2020

Nthing compost tea, it will soak into the soil right past the mulch.
posted by padraigin at 4:23 PM on October 1, 2020

Response by poster: Thanks for your input. Turns out that I have an unlimited, free-for-the-taking supply of arborist wood chips 2 minutes from my home. So, I'll put down some compost on top of the existing chips and cover the compost with chips.
posted by kirsti at 8:16 AM on October 2, 2020 [2 favorites]

an unlimited, free-for-the-taking supply of arborist wood chips 2 minutes from my home

If I had that, and a hundred raspberry bushes, my raspberry bushes would soon have at least six inches of woodchip over their compost layer.

Arborist wood chips are the best wood chips. They're fresh and green enough not to have lost much of the nitrogen that dried wood chips tend to steal as they break down. A thick layer of arborist chip over compost over year-old existing chip is going to make some very happy soil.
posted by flabdablet at 8:52 AM on October 2, 2020 [1 favorite]