We just built a bunch of 4x8 raised beds this year, but used them for other plants, so I'll be doing sweet potatoes there next year for sure. We do a similar mixture as you, with 1/3 compost, 1/6 medium perlite, 1/6 large vermiculite, and 1/3 coco coir (environmentally friendly alternative to peat moss).

The clay soil area had some of the mixture above, plus local soil, plus amendments from last year.

[–] gingersaffronapricat@lemmy.world 2 points 5 days ago (1 children)

Ooh. Good call on the coconut coir. I’d used it in the past but had issues finding it this year and heard certain types of peat moss were ok. I did a little more digging and it sounds like i should try to find a new source for that coconut cour

[–] zd9@lemmy.world 2 points 5 days ago (1 children)

I got mine from True Leaf Market: https://trueleafmarket.com/products/minute-soil-compressed-coconut-coir-blocks-organic, because there was a bulk sale like 8 months ago. I ordered a huge pallet's worth. If you want even more, I also worked with Coir America to set up a larger bulk shipment, but I ended up going with True Leaf Market.

[–] gingersaffronapricat@lemmy.world 1 points 5 days ago

Very cool. I’ll have to book mark them for future reference. The gardening place I used to get it went out. Ither than that, I was only finding it at pet supply places.