Red Currants are pruned differently to Black Currants.
Most of the problems associated with lack of fruit on red currant bushes is owing to the wrong method of pruning. Get the pruning right at the right time and red currants are hardly ever a problem. There is one very important thing to realize about red currants fruiting, and once you fully realise that, then the pruning is a simple matter and everything falls into place!
Redcurrants produce fruit on what is termed old wood. That is simply to say, branches and twigs that were produced in the previous years. Wood produced in the current year, is classed as new wood, but of course next year it is classed as old wood! Branches that are produced in 2016 will produce fruit in 2017, and also in 2018!
Branches which are more than 3 years old, will still produce fruit, but it will be of poorer quality.
Winter! Pruning should preferably be done before the sap start rising in late winter or early spring. The reason for this being that it is far better to have the life-giving sap rising into the branches that you wish to keep rather than the branches you are going to cut off!
Going on from the second paragraph, which explains on what branches the redcurrant fruits, if you examine your bush in winter, you will be able to see which branches are more than a couple of years old. Redcurrants will produce good quality fruit on a branch for no more than 3 years after which it deteriorates.
First line of action is to prune out these older branches which have borne fruit over the last 3 or 4 years. They can be cut right back to near ground level, or back to a main supporting stem. This will then leave you with branches which were either produced last year or maybe the year before. The thickness of the stem will be a good guide as will the colour and aging of the bark.
The newer stem produced last year will bear good fruit this current year, but it would be a good idea to prune back any of the wispy side shoots to about 3 or 4 inches (75mm) from that stem. This will allow then to branch out and develop new branches that will bear fruit the following year.
Bear in mind all the points given above, and aim for building a well shaped, upright growing bowl shaped bush which will probably start on a single stem for about 5in (15cm) from the ground. Best to make any pruning cuts to an outward facing bud we are after a bush which is not crowded out in the middle.
Any new branches which are sagging should be removed in favour of the upright canes. The sagging branches will be weighed down to the ground with the fruit.
Regular supply of new shoots (canes) is the desired end result, so ensure that you feed the bushes after pruning in early spring with a balanced fertiliser. Do not aim for a feed that is high in potash or phosphate. Nitrogen is the key to good growth especially with regularly pruned bushes.
Redcurrants are one of the popular ‘bush’ fruits that can be grown quite easily in almost any soil type. They are actually related to Gooseberries – another popular bush fruit, so not surprisingly, share some of the same cultural requirements.
Ribes rubrum - to give it its proper botanical name – also has a variant with white coloured fruits., realistically named the Whitecurrant! A good, well-established bush can produce around 8lbs (4kg) of luscious berries each summer, with the berries in trusses of up to 12 berries per raceme/truss.
I favoured the redcurrant at home as a child, as I could more easily and secretly pick a small handful – rather than black currants. For me, they tasted much better, though the slightly acidic taste does not appeal to all.
Redcurrant bushes are best planted where they can get a good helping of sunlight, though slightly dappled shade will also provide a good crop. Full sunlight though, is best. Soil type can be either acid or lime, though not to extreme of either – neutral being perfect. Medium loam is best, but they will also grow on lighter and heavier soils, but seem to resent being waterlogged in the winter.
They flower in spring to early summer with the berries cropping from mid to late summer depending upon season.
If planted in rows, allow for plenty of space between each bush, for they will grow to around 1.2m (4ft) across. The space between plants is good for air circulation, which helps keeping mildew at bay. Space also allows for sunlight and full ripening of all the fruits down the branches, for well grown plats will positively droop with clusters of berries. Some varieties of redcurrant will grow to 1.5m (5ft) tall -the main feature – brought about by proper pruning of redcurrant bushes – is the upright habit of growth.
Planting can take place almost any time in the year – as they are often sold as container grown, or containerized plants. They can also be bought through the winter as pre-packed or bare rooted plants. Choose the site according to that written above, and plant into hole with a good helping of potting compost or rotted organic matter. A handful of bone-meal per plant is always a good planting idea for all shrubs.
Keep them well watered after planting if planted in spring or summer. Autumn planted shrubs should normally fare well, but will still require watering in the first year during the drier spring months.
Caterpillars from the Gooseberry Sawfly will soon strip a bush of much of its foliage. They are not simply a once-off pest, for the breed well and can have two or three batches (hatches) of the little green pests throughout spring and early summer. A good spray at first sign with a fruit-friendly insecticide will do the trick once they have taken hold. It is far better to regularly inspect for the caterpillar larvae, which will be hiding on the undersides of the leaves. Rub them off by hand – not too gently! Follow up with the spray to be sure.
Birds of course enjoy a nice meal of succulent berries, so if you live in a rural area in particular, you might like to consider a fruit cage – what a pain – or simply netting whilst in fruit.
Harvested fruits are bet used immediately – or can be stored for a while in the fridge or even frozen in the freezer.