rhododendrons and azaleas
by gladys jeurink
They are beautiful!!
They are not natives to Nebraska and in general do not
like it here. They will
survive but you’ll have to work a little harder to keep them happy.
They are shallow
rooted and like a damp but not wet soil.
This means in a dry winter you’ll need to water during
Christmas vacation and around Valentines Day (if it is warm enough to
get outside) as some of the rhododendrons retain their green leaves all
winter. Azaleas usually
lose their leaves but still need the water. Quite often I will apply
Wilt-pruf around Thanksgiving and then again on a warm day in late
January. Wilt-pruf is a
waxy spray that coats the leaves and helps to keep the water from
evaporating from the leaves when the soil is frozen, and the plant has a
hard time taking up water.
Our soil is not to
their liking either. Our
soil tends to be near or above 7 pH (neutral) so you’ll have to add
material before planting in good volume. This can be acid peat moss,
pine needles, or other acidic type of compost material, plus
granular horticultural sulfur (not sulfur fungicide). As these plants
require protection from summer hot sun and winds they are often on the
north or east side of the house and close to the foundation which
creates another problem. The alkali and lime dissolving off the cement
foundation, or a driveway, into your soil, raises the pH. Also the water
in Lincoln tests out between 6.5 pH and 7 pH so tends to keep the soil
too alkaline for these plants. They
are like blueberries, holly, and evergreen type trees and like a pH of
around 5.5. Therefore, granular horticultural sulfur needs to be added
at least once a year to counteract this and the tendency of soil to
revert to its natural pH.
been working with azaleas and rhododendrons for years and have now
developed some that do better in our Hardiness Zone 5.
The Northern Lights series of Azaleas do much better than their
ancestors. The PJM
rhododendrons blooms a little earlier, have smaller leaves and smaller
blooms, but can stand more exposure, and do better here in Hardiness
To sum up, azaleas
and rhododendrons grow best:
Mulched to cover shallow roots,
In very acidic soil,
Protected from the wind and hot sun,
In moist soil.
For more information
send a self addressed stamped envelope (SASE) to Lancaster County
Extension Office at 444 Cherrycreek Road, Lincoln, NE 68528-1507 and ask
for NebGuide #G97-1341 (Landscapes for Shade), or NebFact NF77-94 (Plant
Nutrient and Soil Acidity).
and Educational Circulars (G and EC) and some NebFacts (NF) are also
available on the internet. Go to www.ianrhome.unl.edu/search
and type in the name of the plant, or the subject, or the name of the
pest (insect or disease or weed).
June 5, 2005