Blackberries will of course grow wild, outside, all around the UK. But if you would prefer to grow your own than to go out and forage then a polytunnel can be ideal for the purpose. Blackberries can be ideal for polytunnel growing as long as they are managed in a sensible way and trailed along a support, rather than allowing to run wild with a mass of brambles. In order to prevent any damage to your polytunnel, however, it is best to choose a thornless variety. A polytunnel will make it easier with all soft fruits by reducing the fruit you will lose to birds and other wildlife and meaning that your crop will be less dependent on fine weather.
Blackberries will grow in shade, though the growth and the fruits are at their best in full sun. Most soils except very chalky soils will be fine as blackberries are not particularly fussy about the soil in which they grow. However, it is best to avoid a soil that becomes waterlogged. A thornless variety will be better for smaller spaces as it is less vigorous and of course will not scratch the gardener, though if the growing conditions where you plan to place your blackberries are not ideal then you may wish to go for a more vigorous variety (though the more vigorous varieties do usually have thorns).
Blackberries are self-fertile so you will only need one plant for fruits to form. While blackberry plants can take at any time of year, it is best to plant them between mid-Autumn and early winter. When choosing where to place your plants, do not forget how large they can grow. Planting spacing will depend on the varietal you have chosen.
When planting out your blackberry bushes (potted or bare rooted) it is important to make sure that the crown of the bush is level with the soil surface. Do not plant too deeply or the crown may rot, likewise, avoid leaving the crown above soil level as the bush may then fail to establish. Place in a hole slightly deeper and wider than the spread of the plants roots and add an organic fertiliser if required. Add a good quality organic mulch around your plants to help suppress weeds and keep in moisture.
Prune to keep plant within bounds and for good air circulation, which will help with problems that could cause fruits to rot. Remove old stems after they have fruited to encourage the growth of new fruiting stems for the following season.
Harvest blackberries when they are ripe. The timing of this will vary considerably not only due to the variety you have chosen but also due to the growing conditions and weather throughout the year. Blackberries can be eaten straight from the vine or used in a wide range of delicious puddings and preserves.
