After a mild July, where I was concerned all my deciduous trees would come into leaf early, the balance was restored by a very cold August, which confirmed that the season was still very much winter! Now, at last, we should see some spring weather and hopefully time can be spent on other things besides repotting. Your deciduous trees should be coming into leaf (if they haven’t already) and you should have enjoyed some blossoms from such plants as prunus, crabapples and flowering quince.
As the new season’s growth commences on trees that have been dormant over winter, the work really begins for bonsai enthusiasts. Pruning is so important in spring. If you have any peaches, cherries, apricots or quinces, prune back the foliage which elongates very quickly after flowering finishes. This will increase branch development, as well as helping to keep your tree looking tidier.
Carefully watch the development of maples in general and Japanese maples in particular. As the second pair of leaves develops either pinch them off when they are quite small or use tweezers. If this practice is not done, long internodal growth (long spaces between leaves on a developing branch) will occur. An added advantage in doing this is that it will also encourage back budding.
Most species of elm can be pruned back to two or four pairs of leaves to increase ramification. After that, it is a good idea to then allow six pairs of leaves to develop and then cut back again to two or four leaves. Take more care though, when pruning Zelkova, as they resent being pruned back too hard, and a trimmed stem may die back past the point you planned.
Spring pruning is not over yet, as evergreens are growing rapidly (especially privets) and conifers will also need lots of attention. Remember that if there are any parts of a tree which are not developing well, do not prune them until that section has become stronger.
Check any wiring on your trees carefully, as branch thickening during spring may lead to wires cutting in more quickly, leaving unsightly scars behind. It is generally better to not wire during spring for that reason, particularly with deciduous species. Remove wiring from a tree if the branch has set, or replace wire in the opposite direction if it has not.
With so much active growth happening, it is time to start fertilising all your trees (except for recently repotted ones). Whether you fertilise fortnightly at half strength or monthly at full strength or every three months it doesn’t matter, but fertilise you must, if you want optimum growth and health in your trees. What is essential is that you follow the directions of the manufacturer and do not over fertilise. Over fertilising can lead to a build-up of salts in your potting mix, which can burn young roots.
As always, make sure your trees do not dry out. Trees in very active growth, particularly if they have been recently repotted, can suffer damage to their foliage or even die, if moisture is not readily available to the roots.