In December there are boysenberries – which are a blackberry hybrid
We have been growing them for the past five years or so. Our crop has survived the heat of summers past.
It has been easy to grow these berries, and hence I strongly encourage you to have a go, because they are delicious and very expensive to buy.
The first thing to know about them is that they are biennial plants: they need two years to complete their life cycle. The first year the cane grows to its full length then loses its leaves in winter and enters dormancy. The following year in spring, this same cane will produce a collection of flowers.
The first year cane is called a primocane (primo is the Italian word for first) and the second year cane is called a floricane, with flori referencing the floral growth present in the second year. It is this second years growth that produces the flowers that will bear fruit.
It is important to know the plants biennial properties because it is this point that informs the pruning you will do.
Therefore the first year you plant boysenberries the canes will grow their full length but will not produce any fruit. Over winter you will tie the primocanes to a trellis wire. There are various ways to do this depending on what you like and how you want to harvest. One of the best methods is to have two wires set up, one for primocanes and one for floricanes. So that at pruning time you can easily make out one from the other.
Then in spring the primocanes will become floricanes and produce flowers and fruit. In winter you will need to cut these floricanes back to the ground. The new primocanes will grow from the base and once they have reached their full length, will need to be tied away and the cycle continues. Eventually your bramble bush will be full of floricanes, and unless you manage the plant well , it will become harder and harder to find the primocanes or to access them. It is also a good idea to cut back the primocanes a little to encourage lateral shoots the following year and hence more flowers.