Prune back Now - Spirea, Russian Sage, Butterfly Bush and Lifting A Tree's Canopy
Russian Sage - Prune Back Now
If you prune them now then the plants will be full of flowers at a proper height.
If you don't, they will be leggy and odd looking...do not be afraid to cut, cut, cut....
Plants to prune back to a foot or 18 inches above ground now are :
Butterfly Bush Dark Knight (Buddleia spp.)
(courtesy of wayside gardens
Spirea Anthony Waterer and other summer blooming spirea(Spirea spp.)
Limemound and Lemon Princess Spirea and other summer blooming spirea (Spirea spp.)
(photo courtesy of Greenleaf Nursery)
You may also prune certain trees now and remove selected lower limbs to 'lift' their canopy.
This allows more air and light into a space, providing 'filtered' shade which makes the area more inviting and more hospitable to 'understory' shade plants.
'Let your ground be covered with trees of the loftiest stature. Trim up their bodies as high as the constitution & form of the tree will bear, so as that their tops shall still unite and yield dense shade. A wood, so open below, will nearly have the appearance of open grounds…"