Garden Q&A: how can I stop my tree dropping leaves?

Horticultural advice from the experts at the RHS
Question: I planted three standard trees, about seven-feet high, in a row on London soil with horse manure last September. They are all different. One is bushy; one was covered with blooms, and had lots of berries last winter; the other dropped a lot of old leaves, and is now looking very bare except for the new leaves on the outside which look healthy enough. 

Last week I trimmed all of the trees and the bare one a bit more harshly. Before that I had given a foliar feed with a marine type fertiliser. I think the sudden drop of leaves may have been a stress due to heavy rain after a long dry spell. What can I do now to help make this bare tree bushier?  It is slightly more exposed than the others and they all are at the base of a south-facing terrace.

Answer: There may well be two issues here causing leaf drop. Both are a result of being newly planted. If you have soil that is in good shape – it has had manure or garden compost added to it over the years, you can plant without adding any further organic matter. Roots are encouraged outwards to look for moisture and nutrients. If you add this material to a hole, without incorporating it over a wide area, a sump can be created which in wet weather can hold the water and potentially rot roots and cause leaf drop.
 
If you have a clay soil, ensure that the sides of the hole have been roughened up with a fork, to avoid water sliding straight down to the bottom and remaining there. It’s also a good idea to check that root ball is not planted too deeply – aim plant at the same depth the tree was in its container.
 
The other reason for leaf drop may simply be lack of water. It is important to water new trees regularly during the growing season unless there are long periods of rain. Each tree could require at least one bucketful twice a week for two growing seasons. After this time, you can consider that the trees are established.
 
Usually, trees of this size have been pruned ready for sale, so little further pruning should be necessary. With consistent water in dry spells, the trees should leaf out normally in future years.

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