WITH the good weather we have been enjoying, many of you will have spent time sitting in your garden enjoying the fruits of your labours.

But as you look around, a number of you may be thinking that a tree you own requires pruning. So how do you prune a garden tree?

First and most important is do not give it an all-over ‘haircut’. This promotes more new growth; every stem cut encourages three or more new stems to grow.

The centre of the tree becomes a mass of woody stems, air and light cannot penetrate effectively and there is three times more wood to cut out next year. You end up with annual maintenance and effectively a hedge in the sky (see figure 1).

The next important point is never prune out more than 25 per cent of the tree’s growth. If you do, the tree will respond by producing large amounts of epicormic growth or water shoots, bolt upright branches which spoil the natural shape of the tree.

It wants to replace lost leaves (it gets energy to grow from sunlight on the leaves) and rebalance roots and branches (see figure 2).

Next to consider, is the right tree in the right place? For example, a local development near me planted a birch tree in a small garden. Birches want to be 60ft (20m) tall or, to put that into perspective, 10ft short of an English church tower.

If you cut the top off, the tree will produce up to three new leader shoots, all aiming to be 60ft tall.

So if your tree is too big for its space, the best option may be to have it removed by a reputable tree surgeon. More on right tree right place later.

So how do you prune? I use the 4D’s as my guide; first, cut out any branches that are dead, dying or diseased. Next, and more difficult, is to prune for design, to keep the natural shape of the tree. Take out complete branches or laterals, but not more than 25 per cent.

I lay the branches at the side of the tree, take a step back and assess what percentage I have removed. If more that 25 per cent has to come out, I wait till the following year to remove it. This normally delivers a reasonable result (see figure 3).

As for when to prune, the only time to avoid is spring, do not prune when the sap is rising. You run the risk of the tree bleeding to death. Prune either when the tree is in leaf or when dormant in winter.

But above all else, remember right tree, right place and chose well at the time of selecting a tree.

My favourite would be Sorbus aucuparia, the native mountain ash. White flowers in spring, light foliage through summer, orange to red berries in late summer that provide food for the birds in winter and small enough to hang bird feeders from.

Enjoy your gardening.

* For weekly gardening advice, you can follow us on Twitter at @HelmsleyWalledG. If you have a particular problem, email me at mike@helmsleywalledgarden.org.uk or drop me a letter, we will try to help