As spring approaches, berry plants, fruit trees and grapes need attention to perform their best. Here are a few tips to keep in mind as you get out the pruning shears and loppers.
As a rule, berry plants such as raspberries, blackberries, blueberries and currants produce best on young wood. Cutting away the less productive portions of a plant allows more water and nutrients to enter remaining strong buds, stems and branches. Pruning berry plants means removing, shortening and thinning.
Weak or slender wood bears little fruit. Long unbranched stems grow out of reach and produce few fruiting side shoots. Crowded stems are also poor producers.
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Red raspberries: Keep canes or stems 8 inches apart and narrow each row to 12 or 18 inches wide so you will have about 2.5 canes per foot of row. Remove suckers that grow out of the soil and around the base of the plant. Shorten remaining canes that grow from the crown of the original plant by cutting 20 to 25 percent from the top.
Fall-bearing red raspberries: A common variety is Heritage. They produce late season berries on wood grown the same season and are easy to maintain. Cut all canes to the ground in the fall after harvesting or in March, before new growth begins. Prune the canes to the same spacing as outlined above for regular season raspberries and remove the suckers. Do not shorten stems during the spring or summer growing season.
Black raspberries: Shorten the lateral or side branches to eight inches to encourage more flowering and fruiting stems. You can take out some of the stronger stems to prevent crowding as canes fill out in the spring. Pinch the new stem growth when it reaches 18 inches by removing the tip of the stem. This will encourage more lateral shoots that will flower well.
Blackberries: Shorten laterals to about 12 to 18 inches to make plants more compact. Cut out all laterals close to the ground because shade from upper stems will reduce their flowers. Fruit from pruned laterals will be far larger than fruit from unpruned weak wood. Thin canes to 10 inches apart and pinch new canes when they reach 30 inches long to stimulate fruiting side shoots.
Blueberries (plants 3 years and older): Remove small, bushy growth near the base. Each year, remove one or two fruit-bearing branches with the goal of maintaining plants with wood no older than 5 years.
Currants: On 2-year old plants, leave six to eight of the strongest shoots. On 3-year-old plants, remove the weakest wood. On plants 4 years and older, maintain a cutting schedule to have three shoots each of 1-, 2- and 3-year-old wood. There should be no wood in your plant more than 3 years old.
Fruit trees also need attention at this time of year. Uniform branch spacing is important. Remove crowded branches, crossing branches and ones with narrow crotch angles. Water sprouts, the long unbranches stems that often grow straight up should also be removed. Shorten long branches in the main portion of your tree to encourage slower-growing spurs that bear the flowers and fruit. Do not remove all the twig growth from the main stems and branches or you may have problems with sunscald on the bark.
Grapes grow from shoots or buds on canes or branches grown the previous year. Some research suggests that heavy pruning is associated with high sugar content in grapes, while light pruning that leaves many buds on each arm or cane is associated with high juice yields. Whatever method you use keep these points in mind:
• The time to prune is in late winter or early spring while plants are dormant.
• The best fruits are borne on pencil-sized canes.
• Most methods recommend keeping plants pruned to four lateral canes with 10 to 15 buds on each.
• Train two sets of parallel canes on supporting wire fence and tie loosely; when you remove other canes, leave at least two buds on four canes to develop into healthy canes for next season’s crop.
To go into more detail, I suggest that the home gardener read up on fruit production tips. Alternatively, “Fruit Production for the Home Gardener” is available from Penn State for $12 plus shipping and handling. Call 865-6713 or email firstname.lastname@example.org for more information.