Today I'll be showering you with the knowledge I have pertaining to growing your own organic blackberries. Who wants to pay the ever-increasing prices for those darned things, when you can have literally hundreds, if not thousands of blackberries every year for the low cost of... maintaining your blackberry bush(es)! Seriously though, I'll be covering everything you need to know from soil and fertilizer to how much sun your blackberries should have, but first... we need to decide what kind of blackberries you want.
What kind, you ask? Yes, what kind. I'll bet you thought there was only one, huh? Those black ones? Well, as far as I know, yes (with the exception of one which can be red), they only come in black. It's a little more complicated than that though. You have different varieties for different areas they grow. For example, the "Chester" variety is exceptionally cold tolerant, so it would be good for the Montana area or anywhere that ends up having those cold winters. Other varieties, such as "Brazos" are resistant to disease. Some of the more classic ones that you may be fimilar with are: Boysenberries, Loganberries, and Olallieberries. They just so happen to be in the blackberry family.
I personally like the ones that I have in my backyard. There has been some dispute over the variety it may be though. Either way, the type of variety for this one is the prize. It's a thornless type, which is a mild lie because if you look closely it does have thorns here and there. However, they are very small and signifigantly fewer than regular versions. If you were to get a type like this, I'll tell you now that the plant will most likely want to revert back to it's old ways and be thornier then you'd ever believe. Take this into consideration and be prepared to remove the thorny sprouts before they become a larger problem.
That's the thing about blackberries, they're rebels. They want to go where they want and do what they please. In other words, they act like a weed. How? They spread from underground with rootlike extensions called runners. It's probably best if you plant the blackberry in a very large pot and put them on a trellis, as opposed to planting it in the ground... unless you really like blackberries (I know I do). If you give this plant half a chance it'll spread like wildfire in no time, so it's important that you keep it under control.
Okay, now that we've got all the fun stuff covered, time to get down to business. First, I'll tell you about all the stuff needed for planting blackberries in the ground, then I'll tell you about the minor changes for when you plant them in pots.
The first thing you need to consider is the kind of soil you're going use for your blackberries. Generally, blackberry plants aren't too tempermental, so the important thing is that the soil drains well. In other words, when you water your blackberry plant, it shouldn't be standing in water for half the day. Another wonderful thing that would be great for the plant is if you were to have organic material in the soil. Organic material is fully decomposed plant matter and should already be in the soil in some quantity. It's often sold as humus in large bags. If your soil doesn't look rich and near black in color, you can ammend the soil by folding some hummus into it. The blackberries (and any plants nearby) will thank you. Blackberries enjoy full sun and can tolerate some shade as well, but remember, the more sun, the more berries... as long as they don't cook, such as in the desert anyway.
If you're planting your blackberry plant in a pot then a general organic potting soil would work well as long as your pot has an irrigation hole in the bottom of it to let water out. Another side note... when you water any plant in a pot, be sure to water it until water is draining from the hole(s) in the bottom. This will keep your plant healthy and happy, making sure that all of the plant's roots in the entire pot get water. There is another reason for it, but I won't go into detail describing it in this article. Remember, this becomes a large plant, a large pot would be prefered for it. Something along the 15 gallon range at the very least.
I believe this is a good time to tell you that when you plant any plant you need to be careful not to leave any major airspace between the plant and the soil. Large pockets of air will dry out the roots and ultimately cripple, if not kill, the plant. I know it seems like a silly mistake, but it happens more often then you'd think.
As far as a good organic fertilizer is concerned, there is a wide selection on the market, but my favorite of all time is most definitely bat guano. It's really packed with a lot of nutrients and is one of the best organic fertilizers on the market. It can be difficult to find, so you may have to order it online. Most good garden stores should have it in stock. It works wonderfully and I highly recommend it from my own personal experience. How much should you use? Well, you can use quite a bit and it won't harm your plant and the benefits will be astounding. Just keep in mind that there is such a thing as overdoing it. Normally, you want to mix in some of the bat guano or other organic fertilizer you've decided to use in the local soil. You can also put some of the fertilizer in the bottom of the hole itself. If you're going to add the fertilizer later also, I recommend working a generous layer of it into the soil around the base of the plant and watering it in.
It'll probably be a good year or so until your blackberries start blooming and producing a signifigant amount of fruit. The berries only grow on canes that are 2 years old. This is important to note because that means you should probably prune back the ones that have already bloomed. The fresh ones that didn't bloom should be left alone, as they'll most likely bloom next year. Every winter, or when the plant has gone dormant is a prime time to prune. How can you tell when your plant is dorment? When the blackberry plant drops all of it's leaves, it has gone dormant.
There isn't any more to it really than that. A couple of sites that might help you if you want to look into blackberries further and with more extensive detail would be at Oregon State University, I know it's a bizarre reference, but it's there and it's very informitave. Another resource would be on Ehow. With that, everyone should be able to enjoy many blackberries for years to come. If anyone has any questions concerning this article, please leave me a comment or contact me in some way.