Shrubs
need three square “meals” a year, says a University
of Georgia expert. It’s time for “breakfast” now.

When to
fertilize

“Shrubs are about to start spring growth,” said Mel
Garber, an Extension
Service horticulturist with the UGA College of
Agricultural and Environmental Sciences.
“Plants have to have nitrogen to grow. They have to have
time, too, to put that
nitrogen into the leaf and stem tissue before they can use
it.”

If you’re waiting for the best time to fertilize your
shrubs, Garber said, wait no
more. “If you haven’t already done it,” he said, “now is
the best
time.”

Follow up with a “lunchtime” application in May. Then
top off the year with a
lighter meal in September.

Nature’s fertilizing
cycle

In the wild, Garber says, plants recycle their food.
Leaves, berries and spent flowers
drop off and decay, breaking down into nutrients the
plants’ roots take up and use again.
It’s a gradual process.

Lighter doses of fertilizer three times during the year
also reduce the risk of
injuring plants by overfertilizing them.

Nitrogen leaches
quickly

But the main reason for the three-meal approach is that
nitrogen, the key element for
growth and color in plants, doesn’t last very long around
shrubs. What the plants don’t
use, the rain fairly quickly washes, or “leaches,” out of
the soil.

“We have a very long growing season,” Garber said. “A
spring application
of nitrogen will have leached out of the soil in six to
eight weeks. So we make small
applications. We use and lose that nitrogen, then come
back with another small
application.”

The idea is to put only as much nitrogen into the soil
as the plant can take out in a
few weeks. That saves fertilizer and money. It also keeps
the excess nitrogen out of the
groundwater.

Choose the right type of
fertilizer

Garber doesn’t recommend soluble fertilizers for shrubs
in the lawn. Soluble
fertilizers are in a quickly usable form, he said, but
because of that form they also
leach out of the soil much faster than granular
fertilizers. You’d need to apply them more
often.

Specialty fertilizers sold for specific plants, such as
azalea-camellia or evergreen
fertilizers, cost more. And you don’t really need them. “A
general-purpose fertilizer
is all you need for most plants,” Garber said.

Fertilizers with timed-release pellets of nitrogen,
though, are less likely to injure
roots, Garber said.

Time applications
carefully

The six- to nine-month formulations can double the
fertilizer’s effective time. But
don’t expect the full six to nine months of active
fertilizer. The high heat and humidity
of Georgia summers release the fertilizer faster.

Timed-release fertilizers are popular. But split
applications of any high-nitrogen
general-purpose fertilizer such as 18-6-12 or 12-4-4 are
also safe, effective and
efficient, Garber said.

In March and May, a normal application for established
shrubs is a level tablespoonful
of fertilizer per foot of plant height. For young plants,
use only a teaspoonful per foot.
And in September, use a slightly reduced rate.

Don’t fertilize during the summer. Normally intense
heat and frequent dry spells make
Georgia summers a time to maintain shrubs, not stimulate
growth.

Put fertilizer in the right
place

The plant’s feeder roots — not the thick main roots
near the trunk — take up the
fertilizer. To best get the fertilizer to these roots,
scatter it around the drip line, a
line under the tips of the branches. The feeder roots,
Garber said, are just inside to
just beyond the drip line.