Mark's tips on growing blueberries
There is already a lot of information out there about
growing blueberries (see some suggested sources in the
sidebar), so I'll stick to what seems to work in this part
of Rhode Island. (We no longer sell blueberry plants, but
they are sometimes available at Morris Farm, 2779 Warwick
Avenue, phone 401 738-1036.)
Location and soil. Blueberries do best in
full sun; they will grow and produce in half-day sun, but
the crop will be reduced. They require soil that is
acid--pH of 4.5 to 5 is ideal. Most Rhode Island soils are
naturally acid. However, if you are planting in a lawn that
has been limed to raise the pH, you will need to take
measures to lower it. You can dig a large hole and mix in
peat moss, which is naturally acid. (Peat moss is an ideal
medium for blueberries; use at least one cubic foot per
plant, whether or not you need to lower the pH.) You can
also, or instead, mix sulfur into the planting bed to lower
the pH. The soil should be a little sandy, for good
drainage (we have some poorly drained spots at Rocky Point
Farm, and you can see that the plants in those spots don't
do well). There should be plenty of organic material in the
soil. Compost is good, and specialists at the University of
Rhode Island determined that sawdust, both mixed into the
soil and as a mulch, is very good.
Planting. Late fall is best for planting,
but early spring is also OK. If you buy your plants in pots
in the summer, keep them well watered until it's time to
plant in October. Holding potted plants over winter is not
recommended. The bed should be weed free; blueberries
cannot stand competition from grass or weeds. Space the
plants 4 feet apart. Dig a hole to accommodate the plant,
remove it from the pot, if roots are solidly packed tease
them out carefully so they'll grow outward. Place the plant
in the hole, bring soil around it and pack down. Plant at
the same level it was in the pot, or an inch aboveground,
as blueberry roots grow close to the surface and can be
smothered if planted too deeply. Water thoroughly and keep
soil moist until winter. Do not fertilize at this time.
Mulch deeply with whatever you have at hand--wood chips,
chopped leaves, sawdust, or whatever. If you use sawdust or
peat moss, which can dry and shed rain, form the mulch into
a bowl so rain will drain toward the plant. If you have
rabbits, the plant will need some protection; rabbits love
to munch on blueberry buds and branches during the winter.
Care. The first year, make sure the soil
around the plant is always moist. When the blooms appear,
pull them off; you want your little bush to grow big and
strong, not to try and produce berries! (Pull off the
blooms the second year also.) A heavy mulch is very
helpful. Fertilize sparingly--a tablespoon of Miracid in
May, spread thinly at least six inches away from the stem
and watered in, is sufficient, unless you use a woody mulch
such as wood chips or sawdust, which will temporarily tie
up nitrogen in the soil; in that case, another tablespoon
in June and another in July will help. The second and third
years, a little more Miracid, or another fertilizer high in
nitrogen, is called for. An organic fertilizer would be
very good if it is high in nitrogen.
Beginning in the third year, prune during the dormant
season to remove any twiggy growth near the ground and any
anemic looking stems.
After the third year, pruning should be done annually,
bearing in mind that fruit is produced on the previous
season's wood. You want to encourage new growth, and also
to have larger, if fewer, berries. Remove dead or sickly
branches, branches low to the ground, and older, less
vigorous stems.
The bushes will reach maturity in the eighth to tenth year,
by which point you should be pruning annually. If your
bushes grow multiple stems from the ground, remove one or
more of the oldest ones each year, and keep the number of
stems, young and old, to ten or so.
If your bushes take a tree-like form, prune out older
branches to encourage new growth.
Your older bushes should be under a heavy mulch, and will
require significant anounts of nitrogen each year, applied
in May and June. You can calculate the amount of fertilizer
needed by looking up the percentage of nitrogen in your
fertilizer (10-5-5 is 10% nitrogen) and callculating how
much is needed to supply 0.8 to 1.6 ounces of nitrogen to
each mature plant, depending on how heavily they are
mulched, and whether it is a woody mulch. Split that amount
into two or more applications.
By the fourth year you should have begun getting berries,
but you may have to fight the birds for them. We have found
the only effective bird repellent is netting, preferably
hung from wires above the plants and fastened to the
ground.
Varieties. You will want to plant at least
two varieties, to assure cross pollination. There are
dozens of varieties commercially available. See the
Varieties tab for information about our varieties.