By Dan Rahn
University of Georgia
Much of Georgia has been dry this spring, and the outlook calls
for more of the same. So when you plant new container-grown trees
or shrubs in your landscape, you’ll have to water them often. You
know that, of course. But you may not know how critical it is.
New container-grown plants may look like the older plants in your
landscape, but they’re not.
“In a very important way, they’re still container plants for the
first few weeks,” said Jim Midcap, a Cooperative Extension
horticulturist with the University of Georgia.
Think about how they grew before you bought them. “Container
plants are grown in a mixture of bark and sand,” Midcap said.
“That’s because those mixtures drain so well.”
The bark-sand mixtures help nurseries avoid the root rot problems
they might have with potting mixtures that hold moisture better.
The only problem is that they also dry out fast.
Oops
“And once the mixture gets really dry, the bark is very hard to
get wet again,” he said.
Nurseries water their plants every day or every other day to keep
the mixtures from drying out. If you don’t keep that in mind when
they reach your landscape, your new plants might not survive.
“If you let the root ball dry out,” Midcap said, “you may think
you’re watering enough. But because the bark is so hard to rewet,
the plant really isn’t getting enough moisture to survive.”
It’s vital to give new trees or shrubs proper planting holes that
make it easy for their roots to grow into the surrounding soil.
But even if you do, he said, all of the plants’ roots are still
in that original potting mixture for the first four to six weeks.
Water the ‘pot’
“That’s what you need to water,” he said. Until the roots grow
into the surrounding soil, the plant still depends for moisture
on the bark-sand mixture in the root ball. “Water it as if it
were still in the container.”
And keep watering it at least two to three times a week for the
first four to six weeks. “On very warm or windy days the original
bark mixture can dry out thoroughly in 24 to 48 hours, even
though the backfill soil around it stays wet,” Midcap said.
If you delay planting a container plant, water it several times a
week, he said. Water it two to three straight times before
planting to make sure the root ball is thoroughly soaked.
If the root ball still feels dry, he said, soak it in a bucket
for a while just before planting. Don’t plant it if the root ball
is dry.
Watch the ‘lid’
In a clay soil, Midcap said, keep the top of the potting mix
exposed. “If you cover it with a clay soil it can seal it up so
moisture can’t get into that sand-bark mixture as readily,” he
said.
In sandy, well-draining soils, it’s hard to water too much. But
be careful not to overwater in clay soils and areas that don’t
drain well, Midcap said. Overwatering in clay soils can kill
plants just as surely as not watering at all.
If a new plant starts wilting or its older, inside leaves begin
yellowing, he said, don’t give up on your plants.
“All you need to do is get that root ball wet again and keep it
watered properly,” he said. “When it dries out, the root system
shuts down. And then a little later, the top begins showing
stress. Give it enough water to get the root ball wet again and
the plant will start regenerating absorbing roots to take up the
water.”
Then keep up the faithful watering. “Frequent watering of newly
planted container shrubs, without overwatering, is crucial to
their survival,” Midcap said.
(Dan Rahn is a news editor with the University of Georgia
College of Agricultural and Environmental Sciences.)
