May Gardening Tips
for the Willamette Valley
by Rod Smith
Oregon Certified Nursery Professional
© 2002-2017 Rodney A. Smith
All rights reserved.
Annuals from seeds are best planted this month. Started plants can be planted
outside. Fertilize regularly to keep them healthy and blooming.
Dahlias and Gladiolus can be planted outdoors. Use soil and bulb dust to protect them
against insects and diseases.
Geraniums and Fuchsias, both upright and hanging, may be planted outside. If you have
over wintered them indoors, set them outside during the daytime in a sheltered location,
and bring them in at night,for a few days before leaving them outside so they don't suffer shock.
Planting a few perennials in bloom each month will insure continuous flowers in your
Vegetables seeds and starts can be planted now. Plant bush beans every two weeks for
a continuous harvest. Planting both early and late sweet corn will also extend the
Spring Bulbs Care
Remove the spent flowers after they finish blooming so they won't use up energy
producing seeds. Do not cut off the leaves because they are needed to store up food
for next spring's flowers. Remove the leaves when they turn yellow and start to dry.
Prune spring flowering shrubs after they finish blooming. Remove spent flowers, also.
Broadleaf and needleleaf evergreens are best pruned or sheared just before or just
after their spring growth. Pines can only be sheared at the soft candle stage,
usually during May or June, when the needles are just emerging from the candles.
Continue to spray for leaf spot diseases as long as rainy weather continues.
Spray rhododendrons in late May for root weevils if the leaves have notches on the
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 until flowers have dropped off.
Give a second feeding to bulbs, rhodies and azaleas when they have finished blooming.
Grapes should be fertilized with a high nitrogen fertilizer.
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