Bramble Pruning - - - we've got your back

Date: October 23, 2020

Everything you need to know about pruning your brambles…in one place.

Whether you’re growing brambles—raspberries and/or blackberries— in your home garden or a larger-scale farm operation, pruning is an important part of the growing process that helps your brambles prosper and maximize productivity. Bramble roots live for many years, however, the shoots that grow from the roots live only up to two years. Removing old and weak shoots will encourage the growth of larger berries.

Before we go any further, let’s break down the difference between primocanes and floricanes. In primocane, think ‘prime’ as in primary or first. A cane that comes from the roots in the spring is a first-year cane or primocane. Primocanes, or new canes, emerge every spring and they may or may not be fruitful. After winter, when new growth has begun, these overwintered canes are now called floricanes and some varieties only flower, (flori-) on these canes.

Now, let’s take a look at how the experts here at Nourse Farms recommend pruning the many bramble varieties we have. And, yes, pruning recommendations differ depending on the variety. So, pay close attention!

Primocane-Bearing (Fall-Bearing/Everbearing) Red & Yellow Raspberries

Varieties: Polana, Joan J, Polka, Himbo-Top, BP-1, Caroline, Heritage, Double Gold, Anne

The main crop is borne in the late summer/fall, on the tips of canes that emerge in the spring and grow throughout the summer. Most fall-bearers will produce the best crop if canes are cut down each year and only allowed to fruit in the fall.

For fall production only, you will prune or mow all canes to the ground in the late winter/early spring. This is especially beneficial in colder areas. You’ll want to be sure to cut the canes as closely as possible to the soil surface, leaving little or no stub above the ground.

Pruning timing is very important. Carbohydrates move from plant’s canes and leaves into the crown in early winter, and from the crown to the buds in early spring. If canes are cut before all the carbohydrates reach the crown, the new canes may not be as vigorous the following year. Canes can also be cut too late, after carbohydrates have move to the buds. From December to February, most carbohydrates are in the crown, so this is the ideal time to cut canes.

Some primocane-bearing varieties are able to produce bountiful crops on the floricanes as well as the primocanes—including Joan J, BP-1, Himbo-Top, Anne and Double Gold. When primocanes are cut back 2-nodes below where fall fruit was produced and allowed to stand through the winter into their second year, another crop is produced early the following summer. This summer crop develops on lateral branches on the overwintered canes. In order to develop two crops, the plant must be pruned as summer-bearing varieties. After harvesting the summer crop, cut the over-wintered canes to the ground, leaving the new primocanes to produce the fall crop.

Floricane-Bearing (Summer-Bearing) Red Raspberries

Varieties: Prelude, Boyne, Killarney, Nova, Latham, AAC Eden, Encore

These varieties carry one crop of berries during the summer on over-wintered canes. For best yields, immediately after harvest, you’ll cut the canes that carried fruit as close to the ground as possible. Thin remaining new growth to six to eight strong, healthy canes per running foot of row. This allows all the energy to go into development of canes that will be yielding fruit for you in the future. In late fall, you’ll cut canes to 4.5’–5’ to manage the picking height.

Note: Prelude and Nova can produce a fall crop on the primocanes and the primocanes should be cut 2-nodes below where the fall fruit was produced.

Floricane-Bearing (Summer-Bearing) Black & Purple Raspberries

Varieties: Bristol, Jewel, Mac Black, Royalty

Black and purple raspberries generate new growth from their crown or base and send out few, if any, suckers. These plants will typically produce more if they are tipped. This means, the first-year canes, primocanes, are pinched back (remove about 2”) as they reach a height of 5’–6’ through July and August. This practice encourages fruiting lateral branches to grow from the main cane and also keeps plant height in check. Laterals should be pruned to 6”–8” in the late fall. Pinching back laterals can help increase berry size and increase winter hardiness. Following harvest, cut the canes that produced fruit as close to the ground as possible. Thin the remaining new growth to four to six canes per hill*.

Primocane-Bearing (Fall-Bearing/Everbearing) Black Raspberries

Varieties: Niwot

Tipping or tip pruning is highly recommended for primocane-bearing black raspberries. As the new primocanes reach 3’, pinch or cut the tips to force branches (laterals) to develop. Tipping will delay, but prolong the harvest, increase yield, and reduce arching of the canes and tip rooting. Pruning later in the season decreases the amount of time the plant will have to develop branches. Leaving the primocanes unpruned will allow earlier ripening than the tip-pruning option; but canes will become tall and arching and develop fewer berries.

Considerations

Once it reaches two to three years old, Niwot can also produce an excellent floricane crop.

Floricane-Bearing (Summer-Bearing) Blackberries

Varieties: Natchez, Caddo, Ouachita, Triple Crown, Chester

Tip primocanes when they reach 5’–6’ feet in midsummer or 6” over the top wire of the trellis. Tipping stops terminal growth and energy goes into development of fruiting laterals. Laterals should be cut back to 6”–8” in late fall. These canes overwinter and produce a summer crop. These fruiting canes should be cut to the ground as soon as possible after harvest has ended to allow all the plant energy to go into the primocanes which overwinter and generate fruit the following summer. Thin out the number of canes (primocanes) to six to eight canes per running yard of row or per hill*/plant.

Considerations: Rotating Cross Arm Trellis

Here at Nourse Farms, we have great success growing floricane-bearing blackberries on the Rotating Cross Arm (RCA) Trellis, made by Trellis Growing Systems. This trellis, and the pruning and training technique that goes along with it, gives growers the ability to lay their canes down so they can be covered as winter protection. This system can also reduce sunscald because blossoms will grow one side of the trellis, where the fruit can be protected by the foliage.

The training method for the RCA trellis involves loosely securing primocanes to a low horizontal wire, 18” high, and tipping them when canes reach 5’ or the next plant. Laterals are then trained vertically, up the trellis, in the way that primocanes are traditionally trained. In the fall, the posts are rotated/lowered, so they lay on the ground and are covered with a heavy, floating row cover. In spring, the row cover is removed, and the posts are rotated up.

To prevent sunscald, just prior to bloom, the posts are adjusted so they are parallel with the ground. This causes the blossoms to emerge on the upper, sunny side of the trellis. Once bloom has begun, the trellis can be returned to its upright, standard position, with all of the blossoms on the shade side of the trellis, thus protecting them from direct sun exposure and reducing sunscald. This technique also increases picking efficacy as rows can be more efficiently picked from one side.

Primocane-Bearing (Fall-Bearing/Everbearing) Blackberries

Varieties: Prime Ark 45, Prime Ark Freedom

Primocane blackberries respond very favorably to tipping. As the primocanes reach 12–15” in height, break or cut ¾–1” off the tip to force the cane into branching (laterals). A second tipping should be performed as the lateral branches reach 30”, again breaking or cutting ¾”–1” off tips. This process stimulates earlier fruit development, increases yield and also keeps plant height in check for easier management and harvest.

The main crop is generated in the late summer—on the tips of canes that emerge in the spring and grow throughout the summer. Fall-bearers will produce the best crop if canes are cut down each year and only allowed to fruit in the fall. Just like we mentioned with the primocane-bearing red and yellow raspberries above, for fall production only, prune or mow all the canes to the ground in late winter/early spring, this is especially beneficial in colder areas. Be sure to cut the canes as closely as possible to the soil surface, leaving little or no stub above the ground.

Refresher

Timing is also very important. Carbohydrates move from plant leaves into the crown in early winter, and from the crown to the buds in early spring. If canes are cut before all the carbohydrates reach the crown, the new canes may not be vigorous the following year. This is particularly true for blackberries as carbohydrates move into the crown very slowly. Canes can be cut too late, after carbohydrates have moved into the bud.

Considerations

When growing primocane-bearing blackberries, southern growers may benefit from a single tipping at 3’, leaving laterals untipped. This will delay harvest compared to untipped canes, but advance it compared to double tipped canes while also prolonging the harvest. Southern growers can also benefit from the ability to produce a summer crop on overwintered canes.

Have questions about pruning your brambles that we didn’t answer here? Our incredibly knowledgeable team is available to help! Call us at 413-665-2658 or email us at info@noursefarms.com. We also invite you to refer to our Planting and Success Guide anytime.

*Note: When we refer to per hill we mean per plant. With blackberries, black raspberries, or rhubarb, some growers will plant the individual plants on a mound as opposed to a raised bed where the entire row is hilled. These plants also grow mostly from the central crown and don’t sucker much, unlike red raspberries which spread exclusively through their root system.

Bramble canes being pruned at ground level.