PRUN­ING BRAM­BLES

NZ Gardener - Garden Diary 2018 - - Snip & Tuck -

BRAM­BLES IN THE FIRST YEAR grow in a pat­tern of new canes (called pri­mo­canes), which then pro­duce fruit in the sec­ond year (flor­i­canes), be­fore dy­ing off. An­other way to de­scribe bram­bles is that the crown (the base of the plant from which canes sprout) is peren­nial and long-lived, whereas the stems are bi­en­nial so only live for two years.

For the pur­pose of prun­ing ad­vice, black­ber­ries, boy­sen­ber­ries, tay­ber­ries,lo­gan­ber­ries and hy­brid ber­ries are treated sim­i­larly.

Rasp­ber­ries are also a bram­ble, but prun­ing is slightly dif­fer­ent be­tween sum­mer- and au­tumn-fruit­ing types. As a gen­eral rule, each plant has a com­bi­na­tion of new canes and fruit­ing canes. To keep plants tidy and pro­duc­tive, the flor­i­canes that have pro­duced a crop and died off should be pruned off in the win­ter fol­low­ing har­vest. It’s best to wait un­til the plants are dor­mant be­fore prun­ing, as this gives time for car­bo­hy­drates from the flor­i­canes to re­turn to the crown for en­ergy stor­age. Dur­ing the sum­mer, pri­mo­canes will have formed, so don’t re­move these when prun­ing out the flor­i­canes, be­cause they will pro­duce the fruit in the fol­low­ing sea­son.

CUL­TI­VATED BLACK­BERRY va­ri­eties have upright grow­ing canes – un­like their cousins in the wild, which have a trail­ing habit. Al­low the new canes (or pri­mo­canes) to reach 1m, then cut to en­cour­age branch­ing for more fruit on the tips of each lat­eral. You can use man­ual or elec­tric hedge trim­mers to make it quick and easy.

TAY­BER­RIES AND LO­GAN­BER­RIES are hy­brids of black­ber­ries crossed with rasp­ber­ries, but should be pruned like a black­berry. New canes can grow ram­pantly – nearly 2m in a sin­gle year – so tam­ing them by train­ing them along wires is nec­es­sary.

BOY­SEN­BER­RIES are a trail­ing type of black­berry, so naturally spread hor­i­zon­tally along the ground. When cul­ti­vated in or­chards and home gar­dens, these need to be lifted onto a wire frame to sup­port the canes, which will make pick­ing eas­ier.

Prun­ing of boy­sen­ber­ries is an an­nual win­ter event. The canes at­tached to the wires will have died back, so these need to be re­moved. Dur­ing the pre­vi­ous sum­mer, new growth will have sprouted, and will prob­a­bly be ly­ing un­tidily on the ground. These long canes should be care­fully gath­ered up with gloves to avoid the spines, lifted and wrapped around the wires. An­other way to deal with the nat­u­ral growth of boy­sen­berry canes along the ground is to have a split wire sys­tem. One side (for ex­am­ple, the left) holds the fruit­ing canes, while the other side (the right) has the new canes grow­ing up (in­stead of just be­ing left along the ground).

In win­ter, the fruited canes on the left will have died off, so should be re­moved. In the fol­low­ing sum­mer, the right side canes will be fruit­ing, and the new canes will be trained onto the left side wires. Each year, you should al­ter­nate the train­ing from side to side.

SUM­MER-FRUIT­ING RASP­BER­RIES STEP 1: In au­tumn or win­ter, re­move all the older canes that pro­duced fruit in the pre­vi­ous sea­son, cut­ting close to the crown at the base of the plant. Take care not to dam­age or re­move any of the newly grown canes – these will pro­duce the first crop of ber­ries the fol­low­ing sum­mer. Your goal after prun­ing is to have 10-12 fruit­ing canes per plant (or per me­tre, if grow­ing in a row). Some va­ri­eties with less erect canes will re­quire wires for sup­port.

Prune the new canes back if their height in win­ter reaches way above the sup­port wires. Also con­sider the height in re­la­tion to the weight of the fruit – you don’t want weighed-down or bro­ken canes. Don’t prune the tips of the new canes by more than 25 per cent though as this will re­duce your crop. STEP 2: Next, re­move any wan­der­ing canes sprout­ing out­side of the des­ig­nated rasp­berry bed. Rasp­ber­ries have a large root sys­tem and will send up lots of suck­ers, some­times a me­tre or more away from the par­ent plant, so keep an eye out for es­capees and cut them off at ground level where they emerge. Don’t let the rasp­berry bed get too wide, as it will make prun­ing and har­vest­ing dif­fi­cult, as well as in­creas­ing the risk of fun­gal dis­eases get­ting a toe­hold. In hu­mid ar­eas, con­sider prun­ing spent rasp­berry canes in au­tumn to en­cour­age air move­ment and pre­vent dis­ease. The time you prune is not the most crit­i­cal, so long as you do it be­fore spring, but it’s eas­ier to see what you are do­ing when the plants have lost their leaves.

AU­TUMN-FRUIT­ING RASP­BER­RIES fruit on canes pro­duced dur­ing the cur­rent year, so prun­ing them re­ally couldn’t be eas­ier: all canes should be cut off at ground level in win­ter. The new canes that grow next sea­son will fruit at the end of the sum­mer and into the au­tumn, so se­lect the strong­est 10-12 fruit­ing canes and tie them in to the sup­port­ing wire.

You can also buy dual-fruit­ing va­ri­eties; these fruit in sum­mer and again in au­tumn. After they have fin­ished fruit­ing in au­tumn, cut by half the stems that have just car­ried fruit back. In spring those stems should put on fresh growth at the tip and it’s this new growth that will bear fruit in the sum­mer. Then, once the fruit has been picked, cut those two-year-old canes back to ground level.

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