What soil mixture for a raised bed?

jackmoore · April 2023

I'm building a couple of new raised beds to start growing some vegetables. What soil should I buy to fill them? Is there a good ratio to follow?

Wolveryeti · April 2023

I have built more than a few raised beds in my time, and never filled them completely for expense reasons. The main benefit for me is to build a bit of soil depth to benefit root crops and as a barrier against weed infiltration. I think on average most of my beds are filled around 15cms above the surrounding soil level. Very happy with the carrots/garlic I've managed to grow.

No need to buy soil necessarily - clippings and even branches and logs can fill the bottom bit (look up Hugelkultur). Also worth being on the lookout for people with building/landscaping projects who have soil they want to be rid of - occasionally they crop up on local classifieds/freegle. I would always fill the top few cms with whatever multipurpose compost you use.

Fairygirl · April 2023

It will largely depend on the height of your beds and what you grow in them.
I have lots of raised beds of varying sizes, and although they're mainly ornamental, I fill them according to what I wish to grow. The bigger ones are around 18 inches high, and have lots of old turf in the bottom. That helps to keep a good base in them, and it can be useful if you're in a drier area as it will help retain some moisture. I topped them up with purchased compost - any old stuff as it was largely as a filler, some soil, and now my own compost, leaf mould, or a mix as the level always sinks over time. That's less of a problem for veg though.
I've been collecting molehill soil for some projects rather than buying any compost so that might be worth looking for if you have any fields/parks nearby. It gets you a few funny looks though

A lower bed will just need any organic matter and soil/compost - enough to give a good depth for any plants that need it. Avoid a rich mix if you're growing carrots.

Sheps · April 2023

I filled mine this afternoon, probably 50/50 with shop bought compost and topsoil, then once it's settled I'll finish off with some more topsoil.

Dovefromabove · April 2023

@Sheps 😊 … those look quite shallow to me … what are you planning to grow?

Sheps · April 2023

Hi @Dovefromabove the plan is just salad crops this year, Lettuce, Spring Onions and possibly some of those very short carrots.

jackmoore · April 2023

Thanks all. Think I'll go with 60% topsoil, 20% compost and 20% farmland manure. I've also found some worm castings that I'll add to the mix.

What soil mixture for a raised bed?

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