Date: Fri 22-Sep-1995

Publication: Bee

Author: SHANNO

Illustration: C

Location: A-12

Quick Words:

transplant-root-growth-soil

Full Text:

Suburban Gardener -

Transplanting Myths Vs Realities

By Anthony C. Bleach

Tradition used to tell us that soil amendments should always be used in the

planting hole, but as the "optimum" amount seemed to vary from five to 50

percent by volume, one or two skeptical agronomists in the 1970s began a

long-term study on some transplanting techniques.

Every planting season, I review the summary of this work in Carl Whitcomb's

Establishment and Maintenance of Landscape Plants . Here is his advice:

Match the requirements of the plant with the conditions on the site carefully.

Look at such factors as tolerance to shade, wet soil, exposure, eventual size

and shape. Matching the conditions on a planting site with the plant is the

single most important factor influencing plant establishment.

Dig a planting hole at least 18-24 inches larger than the root ball. It is a

myth that roots grow down deeply. Most spread near to the surface, so the

wider the hole the better.

Planting too deep is often the cause of predisposing new transplants to

cultural, insect and disease problems. Many times the gardener is planting to

the top of the ball and even one to two inches higher to allow for settling

and for a layer of mulch.

But often, repeated handling of the balled and burlapped tree causes the soil

within the ball to be pulled up around the stem of the plant. Unless this is

pulled back down, you will be planting two to three inches too deep.

Excess mulch is also a common mistake. Steve Heywood of Bartlett Tree Experts

writes you should never exceed the one to two inches that occurs in nature.

The problems with excess soil and mulches around the stem and root zones is a

decreased ability to obtain oxygen. In addition, excess soil or mulch can make

the bark consistently wet above the root zone. This can affect the plant's

cold tolerance, encourage fungal pathogens and insect invasions.

If the plant has been dug balled in burlap, remove the plastic cover and any

string or plastic twine around the stem of the plant. The burlap may be left

in place unless it is plastic. If you have a container-grown specimen, remove

the container before planting for as short a time as possible. The white

growing root tips are the key to rapid establishment and they are killed by

even a brief exposure to air.

Fill the hole around the root ball with the same soil in most cases. Soil

amendments in a small planting hole do not assist plant establishment and

growth. They encourage the roots to stay undeveloped in the rich soil, instead

of growing to their full potential. Water thoroughly while shoveling back the

soil, to avoid leaving air pockets. Do not pack soil, but firm it enough so

the plant is supported.

Remember that aeration is the key to rapid root growth. Make sure any burlap

is buried one inch below or it will act as a wick and dry out the soil. Mound

the remaining soil in to hold water around the tree.

Keep grass and weeds away from young trees. It is best to clear a circle, five

to seven feet in diameter, around the tree and spread mulch three inches deep,

everywhere except near the base of the tree.

Do not place black plastic below the mulch, as it cuts off the oxygen supply;

porous weed barrier fabrics are better. Do not use limestone rock as a much,

as it will make the root zone too alkaline.

Plants grown in the fall while the soil is still warm establish more rapidly

and nearly guarantees a successful planting.

(Anthony C. Bleach coordinates and teaches the horticulture programs at

Naugatuck Valley Community-Technical College in Waterbury.)