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 1950 will produce fruit in 1951, and also in 1952! 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.