Care and Cultivation of Raspberries
What to do first
Bare-root canes - After unpacking, inspect the roots and, if dry, stand the plants in a bucket of water for up to an hour (not longer) to moisten the root system thoroughly.
Plant as soon as possible but, if ground is not ready or too wet, temporarily ‘heel’ the plants into a shallow trench on a spare patch of ground, covering the roots with moist soil. Alternatively, if there’s no ground available in a workable condition, wrap the roots in damp hessian or newspaper to protect them from drying and stand the plants in a cool shed or garage until conditions improve.
Potted canes - Water them if they look dry and plant as soon as possible. If ground is not ready or soil conditions are unsuitable, stand them temporarily in a sheltered place outdoors. Check them regularly to ensure they don’t dry out.
Soil Preparation and Planting
Raspberries will remain in the same patch of soil for a number of years and need good soil preparation as well as a strong support system. A slightly acid soil suits them best and on heavy soil they will do better if planted on a raised bed or ridge. Choose a sheltered, sunny area of the garden away from cold drying winds. Although raspberries tolerate part shade, they fruit best in sun.
Plant in rows 1.8m (6ft) apart, each running north to south to catch maximum sunlight and supported on a system of posts and wires about 1.8m (6ft) in height. Strain wires horizontally between the posts at 60cm (2ft) intervals, starting with the first wire at about 45cm (18in) from the ground and rising to the last wire at about 1.7m (5½ft) high.
Raspberries require a well-drained, rich, moisture-retentive soil to thrive, so dig out a trench where the row is to be and incorporate plenty of well-rotted organic matter like farmyard manure into the soil at the bottom.
Be sure to remove all perennial weeds as you dig and, just before planting, rake in a dressing of a balanced fertiliser such as growmore or blood, fish and bone to give the plants a boost this season.
Plant bare-root canes with the roots well spread out in each planting hole, setting the plants out 40cm (16in) apart. The uppermost roots should be no more than 5cm (2in) below the soil, since deeper planting will discourage plants from producing new canes this season. Set potted canes so that the tops of the rootballs will be about 2.5cm (1in) below the soil surface. After planting, tread the soil around the roots to firm the canes in.
Finish by cutting the stem growth back to approximately 25cm (10in) above soil level. Plants establish much better if they are not allowed to fruit in their first season.
Since raspberries are often attacked by birds, particularly when grown on allotments, take this opportunity to provide supports for bird-proof netting. A permanent fruit cage, though initially expensive, is the easiest to manage.
Raspberries benefit from an annual mulch of organic matter, like well-rotted manure or good quality, weed-free garden compost, to suppress weeds and conserve soil moisture. Spread it thickly every spring on the surface of the ground while the soil is still moist from winter rain.
Gradually over the years it will improve the soil’s structure, drainage qualities and ability to hold plant nutrients in the root zone. Each year in March, at the same time as you mulch, top-dress the plants with some balanced compound fertiliser and a high potash fertiliser to encourage flowering and fruiting. When you weed round raspberry canes, be careful with the hoe, since these are shallow-rooting plants which are easily damaged by an over-enthusiastic hand. In dry weather, and particularly on light soils, give canes a generous watering about every two weeks.
Summer-fruiting varieties carry fruit on wood produced in the previous season. Each year, immediately after you’ve picked the crop, cut the fruited canes back to the ground. Then select the healthiest and most vigorous of the young growth produced in the current season, cutting out the rest. Tie in the new canes so that they are spaced about 7.5-10cm (3-4in) apart on the wires. You should aim to have 6-8 fruiting canes each year per raspberry ‘stool’ or plant.
At the end of the winter, cut the new canes back to about 15cm (6in) above the top wire. If this is not done the tops may later snap off under the weight of fruit.
Autumn-fruiting (Primocane) varieties are pruned in exactly the same way, cutting the old canes back to soil level each year. However, since these fruit on the current season’s wood, prune the canes in February. The strong growth made during spring and summer will carry fruit in the autumn of the same year, at the tip of each cane.