Good planning is key when considering where to plant your blackberry canes. The thornless varieties we grow will reach more than 8' tall if you don't trim them, and new canes will develop in future years in very wide area if the soil and sunlight are ideal. They prefer a rich, well drained soil but can grow nearly any where that there's at least partial sun and you are prepared to fertilize them for a needed boost.
Here's a picture of a newborn quail and an enormous blackberry from our patch; both arrived in the same hour. Yep, that's a very small bird AND a very large berry that's half as wide as my hand!
Tenderly remove your blackberry plant from the pot, taking note of the root size and shape. Dig a hole wide enough that the roots have plenty of room to expand. Put in some of the top soil you got from digging the hole, and add some into the bottom and onto the roots as you fill the hole. Plant blackberries at the same depth as they were in the pot, and don't add fertilizer when planting.
Plant them 3' apart; if you're creating multiple rows then space the rows 8' apart. Training the plants onto a trellis will keep your berry patch more tidy. And of course, if you don't plant them on against a fence then you'll more easily be able to reach the prolific berries from both sides of the bushes.
Prune your main blackberry canes to 3 to 4' tall, and side branches to about 12", leaving 5 or 6 buds on each. Fertilize your blackberry plants each spring and just after harvesting the year's berry crop. Mulching around the plants is recommended. Canes should produce for 2 years then the old cane dies, and fruiting will occur on this year's new canes. Cutting out old canes in the fall will help keep your bushes more tidy and much healthier, and produce bigger berries.
The only real pest we encounter on our blackberries are Japanese beetles and June bugs. My policy is to plant enough to let them have some rather than spraying any type of poison that thwarts them. I DO NOT recommend those beetle trap bags; the scent simply lures more beetles.
Watering after the first year is rarely needed unless a severe drought occurs. Blackberries are pretty tough plants, but if you need to water then give them a long slow watering of 1 inch or so of water with the hose simply trickling into the surrounding soil, every 10 days. Do keep an eye on them during fruiting as this is the time you want to make sure their thirst is adequately quenched.
TIP: if you allow a patch of wild blackberries to grow nearby then they will cross pollinate with your thornless blackberries and reward you with bigger fruit and more berries! (I personally won't go near a wild blackberry bush and fight those thorns, but we do let some grow for this reason).
A good source of B vitamins, vitamin C, and vitamins A, E and K. High in fiber and their dark blue color makes them high in antioxidants.
Store unwashed berries in shallow containers in the fridge for up to 3 days and wash (Shallow containers help keep them from crushing each other). Or lay them individually on a cookie pan and freeze them then store in a bag in the freezer for up to 6 months for a fresh taste of summer any time!
The all-time favorite in our house is blackberry cobbler, blackberry jelly and blackberry hand pies, but why stop there?
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