Blackberry & Hybrid Bushes
Planting
Blackberries need a fertile neutral soil to crop well (a pH of 6.0-7.5 is ideal) with good drainage in full sun. Two pairs of horizontal wires, 60cm (2ft) and 1.2m (4ft) above ground, will be required to support the fruit-bearing canes in future years. The planting distance will depend on the variety. Compact varieties can be planted in the open ground 1.8-2.4m (6-8ft) apart, but more vigorous varieties may require up to twice the amount of space. 'Reuben' blackberry has an upright habit and can be planted as close as 0.5m (20in) apart or grown in a large pot. It can be supported with a stake. 'Black Cascade' has a compact, trailing habit and is suitable for growing in a pot or hanging basket.
Plant your bushes as soon as possible after receipt. Should weather conditions be adverse (i.e. if the ground is frozen or too wet to plant), then the bushes can be left in their pots in a sheltered spot or if bare rooted should be temporarily heeled in until conditions improve. Dig a hole or shallow trench and cover the roots loosely with sufficient soil or compost so that no roots are exposed to the air.
Improve the soil structure by thorough digging before planting and if possible mix well rotted manure or compost into the top soil.
Soak the roots in water for 1-2 hours. Dig a hole comfortably large enough to take the rootball, remove the pot and plant, ensuring the top of the rootball is level with the surrounding soil or up to 1cm (½in) deeper. Apply rootgrow™ mycorrhizal fungi directly to the roots before planting - this will help the plant to establish quickly. Firm the soil around the rootball and water-in thoroughly.
'Reuben' blackberry is very suitable for growing in a pot, while 'Black Cascade' will grow well in either a pot or hanging basket. Start the plants off in a container that is 40cm (15in) in diameter. For greater effect you can plant three 'Black Cascade' plants per hanging basket in the first year. Use a good quality loam based compost such as John Innes No. 3.
Watering
In very dry weather, plants grown in the open ground should be watered thoroughly once a week, especially during the first spring and summer. If growing in a pot, water regularly from spring to autumn to keep the compost moist. This may mean more than once a day in hot dry weather.
Weeding & Mulching
Keep the area around your plant free of weeds, particularly during its first year. An annual mulch of well rotted compost will greatly improve moisture retention and soil structure, and help suppress unwanted weeds.
Pruning Floricane Varieties
Floricane varieties fruit on the previous year’s new wood. To encourage vigorous new growth and help establishment cut all stems back to 30cm (1ft) above ground level at planting time. In future years your fruit will come entirely on the previous season’s canes which then die back to ground level. To prune therefore after fruiting just cut out the canes that fruited and train in the new canes, tying them onto the support wires from where they will produce their fruiting spurs the following summer.
Pruning Primocane Varieties ('Reuben' & 'Black Cascade')
'Reuben' and 'Black Cascade' are primocane varieties. Unlike floricane varieties, primocanes fruit on the first year wood.
'REUBEN' – In March following planting cut all the canes down to ground level. In June/July, once the canes reach a height of 1-1.2m (3-4ft), ‘soft tip’ them by removing the top 2-5cm (1-2in). This will encourage bushy growth. It is important to complete all ‘tipping’ before the end of July. To maximise the primocane (autumn) crop, in winter just cut back all the canes to ground level, clearing the way for the new cane to grow and fruit the following autumn. 'Reuben' can also be used to produce two (smaller) crops a year. To achieve this, instead of pruning all the canes down to ground level in the winter, only remove the top part of the cane down to where fruiting stopped, overwinter and it will crop the following summer. Once the summer crop has finished, the spent cane should be removed completely to give space to the new cane which will carry the autumn crop.
'BLACK CASCADE' – After potting keep your plant compact by soft-tipping the new growth in June and July, thereafter allow the shoots to grow and fruit unhindered. Then in winter cut back hard, re-pot and start the cycle again.
Feeding
Feed liberally in spring using Fruit Feed.
If growing in a pot your plants will need regular feeding during spring and early summer with a balanced (usually liquid) feed. For application rates follow the instructions on the packaging. To keep them growing healthily they will also need fresh compost to root into each year. In the early years this is best done by potting them on into progressively larger pots (or in the case of 'Black Cascade', if you have planted three plants per basket, these should be separated into individual containers). Once the final pot size has been reached (we would recommend a pot that is 45-50cm /18-20in in diameter), remove the clump from the pot in late winter each year, cut or chop away about a third of the rootball from the bottom and around the edge, part fill the pot with fresh compost and re-pot. If after re-potting the compost level looks low, top up with additional fresh compost.
Pests & Diseases
Blackberries and hybrid berries are generally trouble free but watch out for damage to the fruit from the raspberry beetle. If troublesome this may be controlled by installing raspberry beetle traps. Any chemicals should be used strictly as per the manufacturer's instructions.
Further Information
For further information refer to RHS Growing Fruit by Harry Baker. Useful information can also be found on the RHS website.