The variety of blackberries is very small compared with other fruits. There are only two varieties of blackberries which are erect and trailing. The difference between them is the growth habit of their canes. The erect blackberries have stiff, arching canes that are self- supporting and the trailing blackberries have canes that or not self-supporting.
Also the erect blackberries are more cold- hardy than trailing types. You can grow trailing types in colder areas with one condition: leave the canes on the ground and mulch them in winter.
In the next lines I will explain the steps that you should take in order to have a great harvest of blackberries.
First, you should choose a sunny site in your garden with good air circulation and water drainage. Also your soil pH should be 6.0 - 7.0. You should keep the roots moist until you plant them. You should put as much organic matter as you can in the soil and mulch to keep out weeds. You should dig a hole big enough so the roots are not bended. Another good advice is to trim canes to encourage new growth. Also you should plant the blackberries 2 feet apart in rows 7 feet apart. Trim the plant to 7 feet and cut the canes which grow outside of rows.
Second, you should know that the seeds requires stratification and is best sown in early autumn in a cold frame. Also stored seed requires one month stratification at approximately 3 degrees C and is best sown very early in the year. You should plant the seedlings out into their permanent position in late spring of the next year.
Regarding the soil you should know that blackberries prefers light (sandy), medium (loamy) and heavy (clay) soils, requires well- drained soil and can grow in nutritionally poor soil. Also it is good to know that the plant can grow in full shade, semi- shade or no shade. The soil should be moist and the blackberries can tolerate drought.
When you plant the blackberry keep in mind that it is not considered a companion plant. You should plant it away from primary gardens and walkways because it grows very fast and can take over if not pruned frequently.
The best time to harvest the blackberries is as soon as they turn a very dark, deep red/ purple (black in appearance) - hence the name.