Azaleas and Rhododendrons have commanded a prominent place in the landscape of northeast
Ohio for many years. The brilliant Azalea blooms and Rhododendrons, with their large
jewel-like flower trusses, add interest and pizzazz to an otherwise boring landscape.
As beautiful as they may be, if not planted properly, Rhododendrons and
Azaleas can be a source of headache and disappointment to do-it-yourself gardeners.
You can avoid such problems by following a few simple rules for planting and
culture. Remember, when properly planted and cared for, these plants will reward you
with years of beauty and enjoyment.
**These planting instructions should also be used for Kalmia,
Leucothoe, Pieris and Blueberries. Important.. DO NOT follow insect
and disease control on this page for blueberries as they are an edible crop.**
On which side of my house should I plant Rhododendrons and Azaleas? In the country or other open areas, Rhododendrons and Azaleas will usually thrive on
either the north or east side of a house. If planting on the north side, place the
plant three to four feet away from the foundation of your house. In this way, the
plants will receive adequate light when the sun is high during summer. Conversely,
during winter the house will shade your plants from the drying effects of the sun, which
can be especially harmful if the frozen soil prevents a water uptake.
Winter wind and sun can be a damaging combination to your plants. Eliminating
one or both will greatly improve your chances of success.
Blueberries are deciduous so that they need less protection from wind.
On the other hand, those who live in the city will find that any side of the house is
usually god for planting due to the low wind speed factor. Remember to keep plants three
or more feet from the house foundation to allow adequate rainfall to reach the
roots. Planting a few feet away from the house will also avoid damage from the sun
reflecting off a brick or white-sided exterior.
Generous house overhangs, shallow invasive tree roots, or a dense tree canopy over
Rhododendrons and Azaleas spell disaster. Each of these conditions can cause dry
soil which inhibits root growth so the plant does not become established.
Dig the planting hole
at least 3 times larger than the root ball and about 1 1/2 times
as deep. Remove and discard excavated soil if it is hard and
sphagnum peat moss and ordinary good topsoil at a 1:1 ratio.
NOTE: If you purchase topsoil, do not use discount store topsoil
as it is not topsoil. You may purchase real topsoil from
Dayton Nursery in bags. Also, if you use the dry bales of Canadian
Peat, be sure to pre-moisten the peat before mixing with the soil.
Some compost mixed in the planting mix is beneficial as long as it does
not exceed 25%of the planting mix. Sweet Peet is excellent to use
in place of compost but do not use in place of peat moss.
If the soil or the bottom of the hole is hard
compacted clay, fill in the hole with the planting mix and tamp lightly
to prevent settling so that it is 2/3 full. If the soil is loose, loamy
or sandy, fill in the hole about half way with the lightly tamped
planting mix. This is the time to check for the proper planting
depth to accomodate the root ball and to tamp the soil mix before
planting to guard against the plant settling too deep.
Prior to planting balled and burlapped plants,
pre-soak them in a tub of water for about an hour and then let drain
for an additional hour. It is usually not necessary, but you may
soak container plants the same way if the root ball is on the dry side.
Remove the burlap or pot from the plant,
preferably in a shady area, and with a sharp knife, vertically slice
the root ball a dozen times about an inch deep along the sides and
of the ball from top to bottom. DO NOT cut the top of the root ball.
Expose about one inch of the root ends of the
root ball by spraying the ball with a forceful stream of water. DO
the top of the root ball. First picture shows example of root
wash, second picture shows how plant should look after root wash. Click
on images to view a larger size.
Place the plant quickly in the planting hole after
its root wash and immediately cover with the previously prepared
topsoil-peat mixture and lightly tamp the loose soil with your foot
being careful not to damage the root ball. IMPORTANT: In
heavy clay subsoils, the root ball must be elevated at least one half
above the original soil level with the planting mix mounded around it or
it will not drain properly. See diagram below.
Apply about a 2 inch layer of mulch or pine
needles and water thoroughly until the soil is thoroughly soaked.
NOTE: DO NOT use water run through a water softener.
Holly-tone at the rate of 1/2 cup per foot of branch spread for
new plantings. For larger plants, 3 feet or more, use 1 cup per foot of
branch spread. On established plants, double the rates given above and
apply in April, June and October. Iron Plus is a good supplement
for extra iron as acid-loving plants are heavy iron feeders.
Water plants thoroughly until the soil is
well-soaked every 3 days for the first 30 days. After 30 days, water
only when necessary as over-watering in hot weather will bring on root
disease. NOTE: Do not depend on rainfall to water your plants unless
one inch of rain or more falls within a 24 hour period or an extended
cool cloudy period when lighter rain occurs
Note: If weather is warm and sunny (75 degrees or more) water the plants
thoroughly every other day.
Question: Do Azaleas and
Rhododendrons prefer sun or shade? In general, most Azaleas will grow very well if they receive four hours or more of bright
sun per day. Rhododendrons will grow nicely in full sun to moderate shade. A
few Rhododendron varieties such as 'Caroline', 'Scintillation',
Yakushimanum hybrids, 'Hong Kong' and the new hardy varieties from Finland must have some shade in midday or the foliage will yellow or even
burn - especially during a hot summer. On the other hand, if shade is too dense, it can cause fewer blooms and spindly
growth. Dense shade and poor air circulation can also be deadly to Rhododendrons.
The combination frequently results in fungus which attacks new plant growth and eats away
at the plant branch by branch.
Click on picture for a larger size
Question: How much peat moss should
I use to plant?
One 2 ft³ bag of Pre-Moistened Peat Moss will cover:
Size of plant
# of plants one bag will cover
(1 1/2 bags)
(2 1/2 bags)
balled & burlapped
(1 1/2 bags)
balled & burlapped
(2 1/2 bags)
balled & burlapped
(4 1/2 bags)
*The rates above reflect a peat soil
mixture of 1 to 1 with the planting hole 3 times the root ball diameter and
about 1 1/2 times as deep. Sweet Peet may be added in addition to the
peat moss at 1/2 the given rates. To measure the peat moss of a large
quantity of plants, use our volume chart at the bottom of the page.
Question: How should I fertilize
my plants? Newly planted plants may be fertilized with Holly-tone at half the
recommended rate. An application of Iron Plus at the recommended rate is helpful as it
supplies Iron as well as other trace elements. Water the plant well after application.
Also, scatter the fertilizer evenly under the drip line of the plant and never concentrate
it in one spot or next to the trunk! Established plants may be fertilized three times a
year: April 1-15, June 1-15, October 20-November 10. Do not fertilizer after July 4th on
established plants (except for late fall feeding) as plants may become too
soft to go into winter. Always fertilize a Mountain Laurel at half the
recommended rate as they are more sensitive to fertilizer burn. Finally, if the weather is
somewhat dry, water the Holly-tone in thoroughly. Rates to use on established plants: 1
cup per foot of branch spread, double the quantity if the branch spread is three feet or
larger. Important: The above rates should be cut in half for new plantings and for
Question: When and how do I trim my plants? Most varieties of Rhododendrons and Azaleas will respond well to
trimming. Just trim plants to shape. Azaleas may be trimmed anywhere along
their stems and will re-grow new sprouts. Rhododendrons like to be trimmed
just above a fan of leaves as the new leaves will sprout from this cluster
of leaves. You can "pinch" Rhododendrons to encourage bushier growth by
breaking out the dominate center growth bud when new growth buds just begin
to expand in spring. Do not pinch out the fat flower buds! After
Rhododendron flowers fade, remove the old flowers and flower stalks for
faster growth and more bloom the next spring. Trim your plants right after
they bloom. Trimming later in the growing season will cut off bloom for the
next spring and keep disease caused by rotting flowers to a minimum.
Question: What about insecticides and Lacebug?
You MUST apply
Bonide's Systemic Insect Spray at least 2 times per year June 1st and August
15th, as directed, to prevent lacebugs.
As an alternate, you could also use Rose Shield or Plant & Fruit Guard
when bees are not present.
existing Lacebug infestation will turn the foliage a light to golden
The damage shown from Lacewing is spotted discoloration of the upper
surfaces of the leaves. In severe infestations, the leaves become almost
white, many of them drying completely and dropping off. The undersides of
the leaves are also disfigured by the excrement and cast skins of the
insects. The undersides of the leaves may also show brown spots or an all
over brown coloring.
Volume of Peat Moss at 50% of total volume **Remember, our bag of pre-moist peat moss is 2 cu. ft.