July Gardening Tips
for the Willamette Valley
by Rod Smith
Oregon Certified Nursery Professional
© 2002-2017 Rodney A. Smith
All rights reserved.
Cut off old flowers to encourage repeat blooming. Cut delphiniums and columbines back by
half for a fall bloom.
Pruning overgrown deciduous trees and shrubs in the summer will slow down their
growth the following year.
Prune hedges now, especially if you trim only once per year. Make the bottom slightly
wider than the top to keep it from becoming bare at the bottom.
Rapidly growing branches on Apples, Pears and Blueberries can be cut back to 3 or 4
leaves so they will form productive fruit spurs.
Remove blackberry and raspberry canes that have fruited to make room for the new
Continue deep watering to encourage a deeper root system. Lawns need an inch of water
each week when temperatures are near 70 degrees, more during hot weather. Rhododendrons
and Hydrangeas growing in the sun can be cooled down by sprinkling them in the afternoon.
Continue to spray for leaf spot diseases and powdery mildew if plants are watered by
Spray rhododendrons with Orthene twice a month through August for root weevils if the leaves have
notches on the edges.
Check rhododendrons and azaleas for tiny, light brown spots on the underside of the
leaves caused by lace bugs. Severely damaged leaves are almost white. Spray with a
product containing Imidacloprid, such as, Bayer Advanced Garden Tree and Shrub Insect
Control, or Spinosad, such as Captain Jack’s Dead Bug Brew, to prevent lace bug damage.
Both are toxic to bees, so do not use on plants with open flowers.
Spider mites are a serious problem on arborvitae and needle leaf evergreens during
hot weather. Spraying once a month makes them worse. Apply two miticide sprays a
week apart, or according to directions on the package. Hosing down the plants once
a week with plain water also helps.
Use a lawn week killer for broadleaf weeds.
Check lawns for dead spots caused by common cranefly and billbugs.
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