There are a number of (relatively) early flowering trees and shrubs that prefer to be pruned immediately after planting as it gives them more time to produce new wood on which they will flower next year. The list includes Deutzia, Kolkwitzia and Philadelphus.
Trim/clip back Privet, Pyracantha and the hedging Viburnums (such as V. tinus Eve Price).
Please don't forget to water the trees and hedging you planted over the winter and into the spring - it really makes a difference.
You should also keep both newly planted trees and hedging clear of weeds.
And keep an eye out for caterpillars at this time of year. There are one or two processionary moths that can create an infestation in a couple of weeks and thousands of caterpillars can strip young hedge plants (beech hedging is a favourite) in a few days. Either kill them with a proprietory spray, or blast them off with a pressure washer if you do not like using poisons
Fruit needs a bit of attention at this time of year. Fruit trees grown against walls should have any really vigorous side shoots shortened or they become lop-sided. You can also tue in new growths on espalier and fan trained fruit.
Your blackberries, boysenberries, raspberries etc will all be producing new canes (on which they will fruit next year). These will need to be tied in, but try to do it in such a way as to make sure you do not cut them out by mistake later in the year when you remove the old canes....
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