Late August, given heavy rain and sun
For a full week, the blackberries would ripen.
At first, just one, a glossy purple clot
Among others, red, green, hard as a knot.
You ate that first one and its flesh was sweet
Like thickened wine: summer's blood was in it
Excerpt from Blackberry-Picking, a poem by Seamus Heaney
A recent experience has prompted me to dig a little deeper into this amazing perennial food plant. Like most research projects, the more one uncovers about blackberry culture, the more one realizes remains to be learned. This will be an attempt to share some of what I've dug up.
Blackberries, and a few other cane fruits, such as raspberry, share a rather unique growth habit. The plants themselves are perennial but the individual canes, or growth shoots, are biennial. The canes grow vigorously the first season, not blooming or fruiting (or branching much). These canes are known as primocanes. In temperate regions, the shoots thus formed then become dormant and don't normally grow much, if any, during the winter. In the second season growth for last year's primocanes, which are now called floricanes, is limited to a few smaller leaves and flowering side shoots. These blossoms, with proper pollination, become the berries. At the end of this second season the floricane will die back. During the time that the floricanes are flowering and fruiting, the plant is also producing more primocanes for the following season's berries. This means that, after the first year, the plant will have both primocanes and floricanes at once each growing season.
There are several methods of vegetative propagation, or cloning, that may be used to obtain genetically identical plants from established blackberry plants. Last season, in the autumn, I laid twenty flower pots out next to a single established blackberry plant and anchored the tips of twenty primocanes into the potting mix contained therein. This method is known as tip layering (flowerpots are optional, one can simply anchor the tips in the ground). Fourteen of these survived the winter, including the record cold snap this February. I cut them from the parent plant this spring. They looked healthy and I decided, last week, to try selling them using Facebook Marketplace. I took three pictures; one of the largest and smallest plant set in front of the parent plant (which was in full bloom and quite impressive), one of those two up close, and one of all the potted blackberries in my garden cart together. These photos were added to the description and the price - $10 each. They sold out in less than a day.
The other two common methods of cloning blackberries are cuttings from primocanes and cuttings from roots. I think I'll be starting a bunch of cuttings this summer!
The variety I'm propagating is one of the ones developed at the University of Arkansas for commercial growers. The canes are thornless and the berries are big, juicy and sweet. U.of A. has also recently developed the first thornless primocane fruiting blackberry plant, Prime-Ark Freedom. These plants bear on both primocanes and floricanes, which extends the harvest season, something that is an advantage for commercial growers in some areas, since blackberries don't hold up well in storage.