I find it difficult to understand why the pruning of redcurrants and blackcurrants is so different?
Redcurrants fruit on old wood, whereas blackcurrants fruit on last season’s growth. The best results are obtained with redcurrants if the pruning is restricted to the removal of the weaker branches and any necessary thinning out. Blackcurrants, however, crop best when, immediately after fruiting, as much as possible of the old fruiting wood is removed without sacrificing the strongest young growths.
We have recently seen advertisements offering two-and three-year-old blackcurrant bushes for sale. Which would you advise to buy?
In the case of blackcurrants it would be better to plant one-year-old bushes; they would have more vigour than either two-or three-year-olds. Whatever its age, it is advisable to prune a newly planted blackcurrant bush hard—almost to the ground. The time to do this is early in March. It is this pruning that ensures production of strong new wood for fruiting the following season.
Our main interest in growing blackcurrants is for their Vitamin C content—although we enjoy them cooked and like the jam, too. Which variety would you suggest we grow?
As with other fruits, there are varietal differences, and it is generally accepted that ‘Baldwin’ is the blackcurrant with the highest Vitamin C content. This is fortunate as it is a compact grower well suited to garden culture. It is a proven cropper and it flowers late, so it has a better chance than most varieties of escaping the spring frosts. The fact that it also ripens late may not be important if it is Vitamin C you want.
Our blackcurrants ‘Boskoop Giant’ are now eight years old and produce very little new growth, with the result that the fruiting wood is now at the tips of the branches. Each year we have mulched with peat around the bushes, so why don’t they grow well?
Blackcurrants need more than peat: they are hungry feeders, and your bushes are evidently short of nitrogen—and maybe of potash and phosphates as well. When fruiting is finished this season, cut the old wood back hard to produce an open framework and stimulate new growth. Then in February apply Growmore fertiliser at the rate of 130 g/m2 (4 oz/sq yd). Repeat this application each year.
Our redcurrant bushes always lose their leaf colour in July or August, but the ribs of the leaves always stay green. Are they suffering from some disease?
By July and August redcurrant bushes tend to lose lustre in their foliage, but the fact that the leaf ribs of yours remain green indicates a shortage of magnesium, one of the trace elements . Commercial Epsom salts appliedjn the spring at the rate of 65 g/m2 (2 oz/sq yd) should improve matters.
We would like to grow white currants. Are they difficult? If not, what variety would you recommend for a small Middlesex garden?
White currants are not at all difficult, and they seem to have returned to favour in recent years. Like redcurrants they fruit on the old wood. ‘White Versailles’ is an excellent cropper—the berries are large, and the plant is certainly the best white variety for any district.
The new blackcurrant variety ‘Jet’ is said to be frost-resistant. Would you agree that it is the best one for us to plant in Yorkshire?
Its reputation for being frost-resistant may stem from the fact that it blossoms much later than other varieties, and so often escapes the frosts altogether. ‘Jet’ has a flavour of its own, very different from the traditional blackcurrant flavour. Include it as a trial, but remember that the more conventional ‘Baldwin’ always does well in the north.