My family and I are renting a house right now, and looking to buy. One of the first things I want to do when we finally find the right house though is to establish some blackberry plants. The problem I have with blackberries is that they can take up three years before you can start getting a good harvest. I'm not a very patient man. I sure don't like to wait on food, but while fishing last weekend with some good friends, one mentioned that he had some trees growing in containers in his kitchen. This got me started thinking why not start some berry plants in a container, that way when we move I'll be a year up on getting fresh blackberries.
Blackberries and raspberries are not usually grown from seed, they are grown from cutting of other living plants. Berries need nitrogen the most out of all nutrients, and if you grow them in containers you will really need to keep an eye on your soil. They need a pH of 6.0, and adding some compost in your potting mix will help to keep plants healthy.
I'm not much on buying fertilizer for plants. I prefer to do things the cheapest way possible. My plan is to start buying some decent containers. I'm not really sure what size. I've read about people being successful growing berries in five gallon containers, but I've also read that they should be at least two feet deep and two feet wide. I'm going to start with five gallon buckets.
My plan is to get some river rock (I know of a place to collect it, but you can buy it in bags fairly inexpensively at any local garden supply store). Drill some holes in the bottom and layer about six inches of river rock in the bottom of a five gallon bucket. Get some decent potting mix, and add about half volume of leaves that I keep composted around the trees in my backyard. This should give me a decent potting mix that will allow good drainage, but also keep it from drying out to quickly.
Keeping the soil moist will be the most difficult part of growing berries in containers. Of course I have several ideas on how to make this easier, I will have to write up a post on these soon.
The last tip I can think of for growing berries in container is managing the nitrogen in the soil. The last idea I have is to grow beans in the containers with the berry plants. Since beans are nitrogen fixers, this may be the best solution for the two problems. Cheap fertilizer nitrogen fixers from living plants without having to spend money on expensive fertilizers. I'm not sure how well this will work, but it's worth a try. I'll report back later this summer on how well this idea works out.