In article , "graham"
wrote:

I've had 2 blackcurrant bushes for several years and have yet to get more
than 6 or so berries in total!
They flower heavily but very few of them set. The bushes are healthy and
neighbouring redcurrant bushes produce copious amounts of fruit (provided i
keep the aphids at bay).

Has anyone out there any suggestions before I dig them up?

Graham

I have two species & three varieties of currants, though not the black
currant per se. Two of mine fruit well, & the the third didn't fruit at
all for two years but this year fruited a little. The one that has
fruited poorly is the earliest in blossom, so it's primary problem is
there aren't enough bees up & around that early in the year, although it
is also a highly ornamental cultivar & some shrubs developed for maximum
flower don't necessarily have maximum fruiting to follow.

Although currants are by and large self-pollinating (with bees'
assistance), SOME cross-pollinating would even so be helpful. With
blueberries, having two compatible cultivars would be absolutely necessary
to get good crops; it's not regarded as essential for currants. Yet
according to a study by J. B. Free in the 1960s, & studies since,
cross-pollination between distinct but compatible black currant cultivars
increases fruit numbers & size. Black currant will even cross-pollinate
with other Ribes species, such as gooseberries.

Occasionally bees specialize in certain plants and bypass others, so it's
best to have more than one kind of bee in your garden; honey bees are not
picky & even when they do show preferences, black currant is one of those
preferences. But unless someone is keeping honeybee hives in your
neighborhood you'll be reliant on sundry other species of bumblebees &
leafcutter bees & mason bees &c, & you may have to introduce mason bees in
a timely way yourself. If you do any poison spraying for insect control,
probably you'll never have a sufficient bee population, but if you are
organic about it, you can attract more types of bees to the vicinity by
planting flowering perennials that bloom just before & while the currants
are blossoming. If you notice any underground hives on the property, avoid
disrupting them so the bees feel safe & happy & stick around. I lost a bee
hive when I reduced the area that some lavender covered; they didn't like
me shoveling near their hole, & I was very sorry that they shortly after
moved out.

Black currants produce the majority of their fruit on one-year-old wood
that grows from two to three year old wood. So bad pruning technique could
be removing buds, though if you're getting good flowering this wouldn't be
an issue. Removing wood older than three years will concentrate more vigor
in the young fruiting limbs. (Unlike black currants, my red currants
produce fruit on older wood.)

A final consideration is the amount of sunlight a black currant gets.
Black currants is an understory shrub, so likes at least a LITTLE shade.
If the shrubs are extremely exposed & the blossoms are cooked at the
hottest point of the day, it may keep them from setting fruit even if bees
do get to them properly.

Also, if you're on a windy hill, bees will not work in an area while the
wind is blowing. Planting a leeside hedge or having a wooden fence as a
wind break will make it more inviting to pollinate. Our place is on a
hillside & the first two years it was hard to attract enough bees, but we
put in a number of substantial-sized young trees, & now even in high winds
our gardens are pretty calm. That & the increasing number of flowering
shrubs & perennials means we have PLENTY of bees, though I still fret we
don't get enough EARLY bees for early blooming shrubs.

So the main thing is to increase your garden's population of bees,
without whose assistance black currants never fruit well. Set up mason bee
hotels on all sides of the house, but especially in proximity of the
shrubs you need pollinated, as mason bees are short-flight bees (unlike
honeybees that can range for miles) and might not travel even so far as
from one side of the house to the other. With our modern world so full of
toxins, even if you don't use insecticides, your neighbors' use of garden
chemicals could be lowering the pollinator population to next to nothing,
& many gardeners discover there is no part of the year when the number of
bees is sufficient to do a good job. I fortunately live among
organic-gardening neighbors, so we've got several species of bees up the
wazoo, & this year we're even being visited by lots of honeybees though
I've not a clue where they're coming from, I don't see any box hives
anywhere in the neighborhood.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/