Winter pruning a fruitless endeavour
THERE are many reasons why deciduous trees drop leaves in autumn. Mainly so they are able to survive winter. However, in nature there is no waste, so before the leaves are cast, trees draw from them all the nutrients they can.
That’s why they change colour. And these extra nutrients – mainly carbohydrates – are stored mostly in buds, bark and roots, ready for a flying start to spring.
In short, deciduous trees stock up the larder to survive cold times and with enough in reserve to get going again when warmer times return.
This highly vigorous new growth is now sprouting, which is why early spring is one of the best times to prune fruit and other overvigorous ornamental trees to effectively rein in excessive growth in order to control, shape and train them.
The traditional time for pruning deciduous fruit trees, such as apple, pear, plum and other stone fruits, was in the middle of winter.
This was done in the belief that the trees were dormant and we could also see clearly what we were doing and where we were cutting.
However, these trees are packed with energy in winter, so all this dormant pruning did was concentrate nutrients to stimulate even more excessive growth and masses of useless, non- productive wood in spring.
It happened year after year and by the following winter we were always back to square one, with another impressive but worthless thicket of new branches waiting to be pruned again.
It took a long time for it to sink in that we were wasting both time and effort going around in circles.
Of course, some winter pruning operations are necessary. Removing dead or diseased branches, thinning fruit- bearing spurs of apple and rejuvenating badly congested old fruit trees can be done at any time, including winter, and the trees benefit – giving us better yields of higher quality fruit.
That brings us back to why this time of early vigour is perfect for intelligent growth control.
When trees or other deciduous plants sprout all those new shoots in spring, the energy required cannot come from direct sunlight because there are no fully open leaves to act like solar panels.
The real source is the nutrients stored in and around those bursting buds.
So pruning deciduous trees at this crucial time, especially to remove branches that head for the sky, is essential.
This is the most efficient, harmless and effective way of controlling excess vigour.
It works because new growth causes emergency stores of nutrients to become virtually exhausted.
It is this which prevents the trees from getting out of control.
Let’s be clear, cutting these trees back right now may reduce fruit yields, but only a little.
That’s no big deal because all fruit trees over- produce, which is why fruit- thinning is so necessary.
The main advantage is growth control. By fettering over- active growth early in the season we get better access to the fruit, fewer fungal diseases because of better air circulation and, best of all, at the end of the season we are no longer faced with a great sprouting of new, unnecessary growth. So it saves work too.
Just the same, pruning methods are different with peach, nectarine or apricot trees because they form fruit on growth made the previous year.
So we prune these fruit trees in order to stimulate plenty of new, healthy branches to produce bigger yields.
However, even these trees are no longer winter- pruned.
That’s mainly to prevent diseases gaining access through slow- healing pruning wounds.
The best time is during summer, immediately after all fruit has been harvested. They are still in active growth and ensure rapid healing and far less chances of disease infection.
The trees are then heavily watered and fertilised, so by the time winter arrives they already have plenty of fruit- bearing branches ready for a great crop the following summer.