As the heat of summer comes into full effect, most deciduous bonsai benefit from a bit of midday shade. Watch for sun damage and move your tree if the leaves start to wilt or become crisp. Continue to rotate regularly for even growth.
Summer heat also means your bonsai needs to be watered more frequently. Monitor soil conditions closely; this bonsai care calendar suggests watering twice daily.
Defoliation is best performed in early summer after the first growth of leaves has hardened off. Defoliating early gives the tree enough time to produce a second growth.
Bonsai Beware: ONLY defoliate established, vigorous trees.
Early to mid-summer is the best time for wiring; this is when your tree’s branches are most pliable. Wire after defoliating and pruning for fewer obstructions.
Continue pruning throughout the summer; remove branches and foliage that are overcrowded or clash with the aesthetic you’re trying to achieve.
If you missed the window to re-pot before your tree’s leaves opened, you can carefully re-pot once the leaves have fully matured. If repotting in the summer months, trim about 25% fewer roots than you would in spring.