You expect nursery residents to get a lot of loving care.
But many trees grown in nurseries have a
tough time trying to thrive in aboveground pots until they’re
transplanted into the ground.
A University of Georgia researcher, though, has found how to
give these plants that tender, loving
care. He puts them back in the ground.
John Ruter, a research horticulturist with the UGA College of
Agricultural and Environmental
Sciences, has found that a second pot provides something of a
security blanket for young trees
and shrubs. It protects their roots from both heat and cold.
Ruter said the pot-in-pot system helps nursery producers grow
healthier, more vigorous landscape
plants.
“(Consumers) are getting a healthier plant, a plant that grows
faster and has a better root system,”
he said. “It’s not uncommon to get a 30 percent to 40 percent
increase in root growth compared
to a plant grown aboveground.”
The system uses two black plastic pots — the kind nursery
plants are commonly grown in.
Growers set one, called the holder pot, in the ground, then
plant the tree or shrub in the second
pot and place it into the first.
The pot-in-pot system offers several advantages over traditional
single-pot, aboveground nursery
operations.
The second pot and surrounding soil insulates the plant’s roots
from heat — especially important
for Georgia nurseries. In traditional potting systems, Ruter has
measured soil temperatures above
130 degrees in the summer.
“On the south and west sides of the containers, there will be
almost no roots viable for a couple of
inches in,” he said. The heat from the sun can literally cook
tender young roots.
Another advantage of the underground pot system is stability.
Ruter said top-heavy aboveground
pots can blow over easily in even light winds. “This system
keeps the pots upright, even in heavy
winds,” he said.
Colquitt County tree grower Melton Mercer said he likes this
benefit — he doesn’t have to stake
his young trees. And he pointed out yet another plus: pot-in-pot
trees and shrubs use less water
and fertilizer.
“It takes a lot less water than it would with overhead
irrigation,” Mercer said.
Ruter agrees. In many cases, the cooler summertime soil around
the pot keeps water from
evaporating quickly.
When the soil temperature doesn’t reach extreme highs, the plant
grows more actively and uses
fertilizer more efficiently, growing healthier.
Using the pot-in-pot system costs nursery operators three to
four times as much to set up as
aboveground systems. But Ruter said most can recover their costs
in about four years in two
ways: water and fertilizer savings and better space use. With
the pot-in-pot system, growers can
raise up to 3,000 more plants in a 10-acre plot.
“And in the end,” Ruter said, “they’ll have more and healthier
plants for their customers.”
