RAISING "MOPHEAD" HYDRANGEA
These are the instructions that I give to neighbors
and others
who receive any of the plants I propagate.
NAME
The hydrangea you received is
probably a "Nikko Blue" or "Glory Blue" species. There are some 1200 different cultivars of hydrangeas so
I'm not sure of the exact cultivar. It does belong it
the class Hydrangea macrophylla, in the "Mop Head" or "Hortense" sub-class. (i.e.
not a lace cap.)
THIS PLANT /
TEMPERATURES NORTH
This plant is less than a year old. You may keep it in the pot through the winter or you may
plant it this fall. I would wait until the over 80 degree days are gone if you
want to plant this fall. It will survive the winter in the ground unless we get
into single digit temperatures. If you keep it in the pot, you can probably
plant it after February 15th as we may get some
freezing days after that, but probably not into single digits.
Keep inside when temperatures are
below 20 degrees. I have heard that many hydrangea including Nikko Blue require approximately 900
hours, or about 40 days with temperatures below 40 degrees in order to maintain
their natural blooming cycle. These
hours do not need to be consecutive. I leave my new plants outside all winter
and only worry if the temperatures go into the low teens and single digits
– a rare event in the
SOIL
Plant in good soil. I use a mixture of 2-3 parts commercial
topsoil, 1 part dried manure, and 1 part peat moss. The hole should be at least
twice as large as the pot. After planting add enough mixed soil to form a mound
2-3 inches above ground level. Soak well with a trickle drip or spray.
LOCATION
Locate where the plant will get the
morning sun, but not the hot afternoon sun at least here in the south. Sometimes locating too close to large trees will cause
problems in later years when the plant grows tall. (4' to
6'). The roots of the tree
will take so much water from the ground in the summer that mature hydrangea do
not get enough water. You can also locate
them in full shade but they may not reach full height for many years, if at all. Plant hydrangeas at least 4' apart. If I am starting a new area, I plant
them about 2’ apart with plans to remove half of them in about three
years.
WATER / FERTILIZER
Hydrangea like water (hydra is a
Greek word for water). The leaves
will begin to droop if the soil is too dry. Some wilting in the late afternoon
on hot summer days is fine – as long as the leaves spring back to normal
overnight. Too much water and the
leaves begin to get brown/black marks on the edges.
Use Miracle-Grow for Azeleas (used to be Miracle Acid to fertilize the plants. Follow the printed instructions - use approximately every
two weeks in the growing season for maximum size. I have started using Osmocote
as a slow release fertilizer with less risk of burning th plant. Two tablespoons under the canopy early in
the season is plenty for a mature plant with perhaps a one tablespoon booster
after blooming, mid to late summer depending on variety. For small plants use
half that amount.
CHANGING COLORS
H. like an acidic soil - especially
if you want the blue blooms. To supplement
the fertilizer and add acid, you can use any of the following: aluminum sulfate
(1/4 oz. per gal. of water), egg shells, coffee
grounds, or ground up orange or grapefruit peels. If you want pink blooms, use less acidic
fertilizer. Some lime lightly applied may be OK. Be
careful to not make the soil too alkaline as that is not healthy for hydrangea.
STRESS / FUNGUS / INSECTS
If you detect black spotting or
brown/gray coloration in the leaves, and you haven't been watering regularly
and/or the leaves have been drooping between watering, these may be signs of
heat stress or fungus. Increase your watering.
Spotting or discoloration, if you
have been regularly watering, may be a sign of a fungus. Fungus
can come from over watering, watering too late in the afternoon (after
Similarly, if you find evidence of
leaves being eaten, you may apply any all-purpose
insecticide. Follow directions. Not
all leaf damage is from fungus or insects. You may find isolated leaf damage
from branches falling from above punching holes or some staining and holes from
bird droppings. These are perfectly natural.
Another condition you may encounter
is sun scalding. If you have a
quick rain followed by a very hot sun, the remaining water can burn the petals and
you will get smooth, almost round, brown spots. Not much you can do about this.
BLOOMS
Buds start forming in late January
and early February. They are not as
tolerant of freezing temperatures.
Late freezes after the buds start to form are a leading cause of no
blooms later in the spring.
Blooms will start forming around the
middle of April with the blooms out in early June. They will last until the end of June.
Since these are first year plants, I recommend cutting just the blooms off as
soon as they begin to grow more than an inch or so across. Do this through the
end of next summer to let the plant mature with larger leaves and more stalks.
The blooms are pretty, but will cause the plant to not grow as much. If you want
them to come in to a full color, enjoy the blooms for a couple of days, but
prune them soon to improve the long term health of the plant.
On a mature plant, the blooms will
last some 4-6 weeks. They start
almost white and then turn pink or blue depending on the soil. Some plants and
even some blooms may have both pink and blue on them. As the blooms mature, they turn to a more
purple/lavender color, then to lime green, and finally white & brown. Let them stay on the plant or cut them
off. I cut them when they turn green as this seems to spur growth on the nearby stalks. Some cut them for drying.
STEMS / PRUNING
Do NOT cut the brown stems off in
the winter. The brown stems are
what next year's blooms will grow on. You may top them for shaping the plant by
taking off an inch or so on smaller plants and three to five inches on larger
plants. Cut just above a node (joint). They seem to like this
"haircut." The next
winter the brown stems will turn a whiter color and eventually will separate
from the root. You can pull gently
on the whiter colored stems. If
they come off in your hand, fine, if not, leave them for a couple of months and
try again.
On a very full mature plant, you can
remove some of the brown stems completely to encourage less, but larger blooms
the next year. Leave the stems
alone for more, smaller blooms.
GENERAL
After the first full year, you may
choose the level of care you wish to give hydrangea. Except for watering, they require very
little care for good results. Or, you can prune, fertilize, and treat for fungus and leaf
eating bugs if these conditions appear for exceptional results.
With a lot of care I have had cobalt
blue and brilliant pink mop heads as big at 10 inches across and leaves as long
as 12 inches and as wide as 9 inches. The plant will grow from 4' to 6' tall
with good soil, watering, feeding, and morning sun location.
If your plant doesn't
make it for any reason, let me know and I'll get another for you. Any questions, please call me at
205-987-5315 weekdays, or email me at cpsmith@conweb.com. The latest version of
this document can be found at http://www.conweb.com/hydrangea/instructions1.shtml
CONTRIBUTIONS
Contributions may
be made to the Sherry Millard Memorial Scout Leader Training Fund, c/o Christ
Church United Methodist,
Pete Smith 
Revision
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