I currently have my blackberry and raspberries in large containers and grow bags. Next year I will be building raised beds, on my driveway so it won’t be in ground at all. My plan is to have it 12-18” deep, it will have a bottom lined with hardware cloth and landscape fabric for drainage. I need to plan for the mix that I’m going to fill it with. What would be a good base, since the soil will have to have last for years with just top dressing and fertilizing. I was thinking 50/50 blend of compost and peat/coir, then add 20% by volume of hydroton or perlite. Then add the stuff like gypsum, rock dust, bio-char. I’ve read neem meal is good to mix in as slow release fertilizer and pest repellent.
I may be over thinking this, as I’ve been watching a lot of gardening videos and reading about soils used for indoor medical grows.
i like to use pro mix bt from tractor supply 50/50 mixed with good compost and a few bags of floor dry coarse D.E from napa auto parts. the D.E helps hold more water and also adds silica to help strengthen the plants. might also help if you add some old rotten firewood in there before you add the soil. it will also help hold more water. kind of like a hugelkulture mound does. it also will save you some on soil cost. as the wood breaks down, just add some more soil over time. my raised beds are 1/3 wood and have only settled 3in. over the last 5 yrs. in regular years i rarely have to water.
Blackberries do well in a variety of soils, even heavy soils.
Raspberries (long-term) are more finicky and need the excellent drainage.
Because of the different soil requirements, perhaps you can put the blacks and rasps in separate beds.
Oh my OCD won’t let me put them in the same bed and let them grow into each other lol. For each of my varieties I plan on a separate bed or sectioning a bed in half.
have my raspberries in my heavy clay rocky soil and they do fine. even the wild ones grow great in it also. my blackberries grow great in it also.they are one of the few plants that does well in my crappy soil.
I guess I’m hung up on the drainage part, I’m reading that loamy soils is almost sandy in its drainage and how loose it is, but have all the organic stuff mixed in for moisture and nutrients. So maybe a equal part mix of compost, promix/peat, and perlite/vermiculite or sand. The laying of some logs down sounds like a good idea, I’ve seen some videos about that practice, just wasn’t sure how it would work in a bed that’s only 12-18” deep. Granted, I’ve ready that for black/raspberries I just need a 6-8” minimum depth for soil, with some tap roots that go to 12-18”.
id just put a single row of wood no more than 6in. that should help you. the rest sounds good. don’t overthink it. brambles are some tough plants!