Bruce Bordelon, Professor, Horticulture & Landscape Architecture, Purdue University
Blackberries are a popular fruit for the home landscape. They are easy to grow, tolerant of poor soils, heat and drought, have few pest problems, and have excellent fruit quality. The one major weakness of blackberries is a lack of winter hardiness. Most varieties are only hardy to about -10?F, which is frequently experienced in central and northern Indiana. Winter injury is common on blackberries grown in the region and usually occurs as “delayed winter injury” with damage showing up well after plants have started growing for the season (See figure 1).
A new type of blackberry has been developed that will make winter injury a problem with which growers no longer have to contend. Primocane-Fruiting Blackberries bear fruit on the current season’s growth (primocanes) (See figure 2). All other blackberry varieties are floricane-fruiting, thus the canes must overwinter for fruiting the following year. With primocane-fruiting blackberries growers can get a crop every year, even if winter temperatures kill the previous year’s floricanes. These new varieties are similar to the popular fall bearing (or ever bearing) raspberries such as Heritage. In fact, the trait was transferred from raspberries to blackberries through interspecific hybridization. They have the potential to produce more than one “crop” per year, a normal summer crop on last year’s floricanes, and a later crop on primocanes. In the upper Midwest, the primocanes may continue to produce fruit well into fall. We have picked fruit as late as mid-November from our plantings near Lafayette (Figure 3).
Breeders at the University of Arkansas have now released primocane fruiting blackberry varieties for the home grower. The varieties are listed under the trade name Prime-Ark®. The first two varieties released are Prime-Jim® and Prime-Jan®. Another variety was released in 2009 for trial commercial production, Prime Ark® 45 (See Figure 4). More primocane fruiting selections are being tested and more varieties will be released in the future, including thornless types.
For all the northern growers that are looking for an easy to grow berry crop for the home garden, primocane fruiting blackberries may be the answer.
Click image to enlarge