There are a number of trees in my garden and the leaves are starting to turn brown. Is this lack of water?
Drought is having a big impact on trees. Consistent watering is the only answer, and plenty of it.
The problem now will be hose-pipe bans, and unless you are good at recycling your water then the plants will find it difficult.
By mulching around the base of the plant after watering you will ensure that the water won't evaporate too quickly.
Water in the early morning or last thing at night.
This applies also to any container-grown plants.