Cultivated blackberries are very much larger and far more luscious than the wild varieties.
They need little spraying and can be planted in rough corners of the garden or be allowed to scramble over a fence or garden shed.
They will grow in any, although if grown in a sun-baked spot the fruits will be rather dry and hard.
Buy one-year-old rooted layers.
Plant any time between October and March. If planting is to be done in rows, allow 6 ft. between the rows to permit easy access. Erect strong posts at the ends of each row and stretch galvanized wires along the rows from one post to the other at intervals of 1 ft. — the lowest 3 ft. and the highest 6 ft. from the ground.
Put the plants in the rows from 8 to 12 ft. apart according to the method of training to be followed and the strength of the variety. Particularly rampant varieties, such as Himalaya Giant, should be planted up to 15 ft. apart.
Fan training is the most usual method adopted for blackberries that are grown in rows, or on a fence or shed.
Arrange the fruiting canes in the form of a fan. This is a job for two people, because the thorny canes sway about and need to be firmly held by one person while the other makes the tics, first round the wires and then round the canes.
Tie in six or seven canes and remove the remainder, and as new canes grow during the summer loop them together or tie them roughly straight up the centre of the fan, and then twist them round the top wires.
Immediately after harvesting, cut down the old canes and tie new ones in position to replace them. This will allow the new canes to ripen better and to withstand the winter.
A more simplified form of training is to loop three or four canes together and tie them to the supports. This saves labour, provided the new canes are kept together, otherwise they will need to be disentangled late in the summer, which is almost impossible.
Always fasten the new wood higher than the old to avoid any disease spores falling from the old wood on to the new. This, except in wet seasons, is usually sufficient control for cane spot, a disease which sometimes causes trouble. If there are small purple-rimmed sunken patches on the canes in May, spray them with a colloidal copper spray.
Another method, quite commonly used, is to fan-train the canes, fastening the old ones to the right, and the new ones to the left. When the old ones are cut out, the next year’s growth replaces them so that in the second year the new canes are to the right and the old ones to the left. This method saves handling the canes twice in one season.
As the roots grow very near the surface, little cultivation of the ground can be done apart from hoeing to keep down perennialduring the summer. Put a mulch of rotted or sedge peat along the rows in June, and if any of it still remains in the autumn, lightly fork it in after tidying and fastening in the new canes.
In the spring after planting, top dress with superphosphate at the rate of 2 oz. per sq. yd. to strengthen the root growth. To help cane growth, use a nitrogen fertilizer in addition at the rate of 1 oz. per sq. yd. Potash is good for the berries, particularly if the soil is light.
Sever the rooted layers and plant them out the following autumn or spring.
As blackberries fruit on laterals from buds on one-year-old canes, prune out the old canes immediately after fruiting to allow the young canes to ripen.
Sometimes new canes grow from two-year-old wood, so the base of the older canes can be retained if the young canes are to be used in training.
Blackberries are jet-black in colour when ready for harvesting. They have a long cropping season, thus avoiding gluts and consequent waste. Pick all fruit when it is ripe even if it is not required, as this helps the later fruit to ripen.