Pruning tips for Triple Crown blackberries
Question: We have Triple Crown Blackberry bushes at our residence. What is the proper care for these particular bushes? They get overrun with weeds and grass during the late spring to early summer. Should they be cut completely down periodically? Any help or suggestions will be appreciated.
Answer: Triple Crown is a terrific thornless blackberry that’s well-known for its productivity and disease resistance. The flavorful fruits ripen in late summer.
Blackberries can be trailing, erect or semi-erect, depending on the variety’s growth habit. Triple Crown blackberries are in the semi-erect category, which means that their growth habit is somewhat upright but the vines will begin to trail if left unpruned and untrained. With proper pruning, however, the plants can be grown to be fully upright or to trail along a trellis.
There are two different pruning strategies you can take with Triple Crown blackberries. This variety bears its fruit on 2-year-old canes, so improper pruning or cutting the plants down to the ground every spring, as is recommended with some other types of brambles, will result in no fruit production. It’s important to remember that at any one time there can be three different types of canes on each plant: old canes that have already fruited, newly formed canes from the current season (called 1-year-old canes) and canes that were formed the season prior (called 2-year-old canes)
First, if you would like to trellis your Triple Crowns, position sturdy posts every 15 to 20 feet down the row of blackberry plants. I recommend using a 4×4 or a round, wooden fence post. Run two parallel wires between each pair of posts. The lower wire should be about two to three feet above the ground. The upper wire should be four to five feet above the ground. The plants should be spaced every 5 feet down the length of the trellis.
As the blackberry vines grow, attach them to the lower wire first. Then, as the vines grow taller, train them to grow out along the length of the upper wire.
In March, any old canes that have already produced fruit should be cut down to the ground to make room for new shoots to grow. Then, train the existing 2-year-old canes to stretch out along the upper wire. They’ll produce fruit later this season.
As new canes emerge from the ground throughout the growing season, attach them to the lower wire. In mid-summer prune off the tops of these canes so they’re level with the top wire. This encourages the production of lateral buds that will produce fruit next year.
Second, you can prune Triple Crown blackberries to grow as free-standing plants. To do this, in March, cut any canes that produced fruit the previous season all the way down to the ground. Canes from the previous season that have not yet fruited (2-year-old canes), should then be trimmed back to 3 to 4 feet. Any lateral branches on them should be cut back to about a foot. These lateral branches will produce flowers and fruit later this season. Then, in mid-summer, cut any new 1-year-old canes down to 3 to 4 feet in height. This forces the production of the lateral branches that will go on to produce fruit the following summer.
In the fall, when the canes have lost their leaves and gone dormant, prune these newly developed lateral branches back to about 18 inches in length.
Though it sounds complicated, once you get the hang of it, pruning your Triple Crown blackberries is a simple process. It does, however, require diligence, regardless of whether you grow your berries on trellises or as free-standing plants.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden,” “Good Bug, Bad Bug,” and her newest title, “Container Gardening Complete.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to [email protected] or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.