University of Vermont Extension
Department of Plant and Soil Science
Summer News
Article
BASICS OF GROWING BLUEBERRIES
Dr. Leonard Perry,
Extension Professor
University of Vermont
Blueberries are one of the most
popular and healthful fruits, are easy to grow, and can be grown as an
ornamental shrub. Many have colorful red
fall leaves. If you like eating blueberries from the store or picking
your own,
consider if you might have the space and conditions for growing them in
your
landscape. The most important aspects
for growing blueberries successfully are choosing hardy varieties and
having
the right soil.
There are five main groups of
blueberries, representing three main species.
The northern highbush (Vaccinium
corymbosum) and lowbush (Vaccinium
angustifolium) are the main species for northern gardeners, as well
as
hybrids of these called “half-high”.
While the highbush reach from 6 to 15 feet high, depending on climate
and cultivar (cultivated variety), the lowbush only reach a foot or so
high. The half-high reach from 3 to 5
feet high. These northern groups need sufficient
cold to produce flowers, then fruit, so are not suitable for southern
gardens. There you’ll see rabbiteye and southern
highbush cultivars. There are many
cultivars to choose from within each of these groups, varying mainly in
time of
bloom and fruit size.
When choosing blueberry cultivars,
you’ll want at least 2 if not 3 different ones for cross
pollination unless
they are one of the few listed as “self fertile”.
Make sure to choose ones from the same group
as, for instance, a low bush wont pollinate a highbush type. Make
sure too that they are listed to bloom
the same time. You’ll find cultivars
listed as early, mid, or late season.
Although this often refers to ripening of the berries, relative bloom
time is similar except for some
commercial cultivars. So the bees can
move the pollen among your different bushes, plant them near each other
or
preferably intermixed.
Other than getting the right
cultivars, you’ll need the right soil for blueberries to
succeed. They
like plenty of organic matter in the
soil, and well-drained soils so roots don’t rot. Perhaps
the most
important point though is to
have acid soils—ones with a low pH of 4.5 to 5.2. You can
probably get
by with a pH of up to
6.0 if you use plenty of peat moss which is acidic. Sulfur also
can be
used to lower the pH. If soils are more alkaline (most plants
grow
best with a pH of 6.0 to 7.0—the latter being neutral), it may be
more
work yearly
to try and lower the pH than worth it.
One solution if the soil pH is too
high is to get a shorter cultivar, such as lowbush or half-high, and
plant in a
container. Just make sure it is large
enough, perhaps 15 to 20 gallon size, or 18 to 24 inches wide and 12 to
15
inches deep. You can plant container and
all right in the ground. If left above
ground, make sure to bring into an unheated shed or garage over winter
that
wont allow the soil to freeze. Ample
ground heat protects roots in the ground during winter, something roots
above
ground in pots don’t get. Container
blueberries also are great for small gardens. When planting in
containers, use
half peat moss and half potting soil.
Once you have the right cultivars,
and soil, plant as you would other shrubs.
Give enough space—at least 5 to 7 feet apart for the highbush, 3
to 5
feet apart for the half-high, and 2 to 3 feet apart for the
lowbush. Add plenty of peat moss or compost, or both,
when planting. Blueberry roots are near
the surface and sensitive to drying out, so don’t allow them to
dry before
planting and water well once planted.
Keep them well-watered until established, and even later when
droughts. Several inches of mulch helps
retain moisture, and helps prevent weeds.
Hand pulling weeds is best so not to damage their shallow roots with a
hoe.
Since blueberries usually begin
bearing fruit when 4 to 5 years old, buying older and larger
plants will give you fruit in fewer years.
You don’t really need to prune bushes, except to remove broken or
rubbing branches, until they are much older.
They do need some fertilizer, such as a cup of 5-3-4 or similar for
young plants, more for larger mature ones.
Apply this in early spring, and perhaps again in late June.
Don’t apply much later so plants will harden
properly for winter. Also you can use acidic
fertilizers as you find for azaleas and hollies.
If leaves are reddish or have
reddish dots, and are overall light green to yellowish, they may need
more
nitrogen such as from ammonium sulfate.
If leaves are light green between veins, this is a common symptom
indicating iron deficiency. This, in
turn, may mean the soil pH is too high.
Check it first, and correct if needed, and the iron deficiency may be
solved too.
Animals don’t really bother
blueberries, but they are a favorite food of birds. You may try
scare tactics such as noise
emitters and bright balloons and objects hung among plants, but the
best method
most end up using is tight bird netting over plants. This netting
is black and of thin plastic
strands that aren’t really obtrusive or even noticeable from a
distance.
Whether you grow your own or just
pick blueberries locally, berries are simple to just wash and freeze
for use
through the rest of the year. Eating
more blueberries, even making and drinking blueberry juice,
you’ll realize a range
of health benefits. Not only are they
the highest fruit in antioxidants, but they contain other compounds as
well
that help your immune system fight infections, help to reduce
belly fat, promote urinary
tract health, preserve vision and brain health, reduce the risk of
heart
disease, aid digestion, help prevent certain cancers, and serve as an
antidepressant
to keep you in a good mood. And you thought blueberry pie just tastes
good!
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