Date: Fri 26-Sep-1997

Publication: Bee

Author: CAROLK

Quick Words:

Gardener-Bleach-plants-trees

Full Text:

(Suburban Gardener column on transplanting tips & foibles, 9/26/97)

Suburban Gardener-

Transplanting Trees: Facts & Fallacies

"But he who received the seed on stony places, this is he who hears the word

and immediately receives it with joy; yet he has no root in himself, but

endures only for a while."

-St. Matthew

By Anthony C. Bleach

Many mistakes at planting time would not happen if we knew more about roots.

Joe Freeman, in Flower and Garden magazine, dispelled some common fallacies in

a recent issue.

Established wisdom tells us we should do the following:

To stimulate the roots of a tree or shrub to grow after planting, we should do

one or more of the following:

Add soil amendments (peat, compost, etc.) to the fill.

Make two to four shallow, equally spaced, vertical cuts along the container

root ball.

"Tease" roots away from the outside of the root ball.

Slice the bottom of the root ball in half and spread, or "butterfly," each

half horizontally.

Research indicates soil amendments do not help woody plants become

established; they are recommended mainly when plants will be located in

confined beds or areas with very poor soil. Likewise, the "slice-and-dice"

methods do nothing to enhance root growth or plant survival after planting.

To establish a container-grown or bare-root plant in its new home, its roots

must grow rapidly into the soil after planting. Two things are critical to

success: loosening the soil in the landscape bed and proper watering.

Tilling the soil or digging the widest possible planting hole loosens and

aerates the soil, which increases root health and vigor, making it much easier

for roots to grow into the new soil.

We know water is important but we forget that, until the plant's root system

grows into the surrounding soil, it depends on a very limited root zone for

its water supply. Note also that moisture does not move from the surrounding

fine soil into the coarser potting soil.

By constructing a ridge of soil just outside the existing root ball after

planting, you create a basin that makes watering easier. Check soil moisture

daily; sandy soils will need more frequent watering than clay soils. To give

the roots a deep soaking, fill the basin with water, allow it to drain, then

fill it again. Note that it may take several months to a year or more before a

tree becomes established and top growth resumes.

It is also a fallacy that we should plant slightly deeper to ensure that the

roots don't dry out. In fact, deep planting suffocates feeder roots and

contributes to the death of many first-year plants. Digging the planting hole

deeper than the root ball allows the plant to settle too deep. Some plants

regenerate their feeder roots, but many cannot and die.

Set the plant so its crown is even with or slightly above the soil surface. In

poorly drained soils, dig a hole only two-thirds as deep as the root ball and

construct a mound to cover the sides of the root ball.

If you think you have planted too deeply, dig and reset your plants

immediately, taking care to cause as little root disturbance as possible. Do

not attempt this task in the heat of summer; however, if hot temperatures

prevail, wait for the cooler days of fall to replant.

Many current sources suggest you should remove one-third of a tree's branches

to compensate for root loss when you transplant. But recent research reveals

pruning young trees reduces root and shoot growth and therefore is not

recommended. Prune only to remove dead, diseased, dying or crossed branches.

They also say most of a plant's feeder roots can be found just outside its

drip line (branch spread). This is where fertilizer should be applied. Roots

grow far beyond the edge of a plant's branches, often three times the branch

spread.

When fertilizing urban shrubs and trees, it is best to spread the product over

the soil surface. In heavy soils, place it around the tree in "pockets" 4 to 6

inches deep - any deeper and you risk placing the fertilizer under the root

system. These pockets help to reduce fertilizer runoff on sloping ground or in

compacted soils where water filtration is low. Tree spikes are perhaps an even

better option.

Generally it is not necessary to fertilize trees growing near lawns or plant

beds. Trees growing in small, isolated or confined areas, however, need a

regular fertilization program. In any event, use compost or a product with

slow-release or organic nitrogen.

Weed killers should be used sparingly. If you must use a weed-and-feed

product, stay several feet outside the plant's drip line for safety. Consider

instead pulling the weeds by hand or spot-treating them where needed.

When transplanting, dig wide, not deep. Digging wide protects feeder roots,

which grow just beneath the soil surface and are most essential to the tree's

survival after transplanting. Because of compacted soil and high water tables,

most trees planted in urban sites don't even develop tap roots.

Almost 80 percent of a tree's roots are located in the top 12 inches of soil,

where oxygen, nutrients and moisture are abundant. About half of a tree's

roots grow beyond the canopy. Thus, even minor changes in the site's grade can

suffocate, injure or remove a large portion of the tree's critical roots,

causing decline or death in the years following construction.

To reduce root damage and soil compaction from heavy machinery during

construction, build a fence around the tree at the drip line. Tree wells

should also be located near the drip line or as far from the trunk as

possible. (Professionally installed tree wells that include drainage tile,

gravel and pipes to aerate roots are suggested in situations that offer no

other choice.)

Even with these precautions, some trees will slowly decline, although the

effects may not show for as many as 15 years. However, simply leaving a small

open area around the trunk won't do any good.

The best treatment for trees damaged by construction is irrigation. Heavy

fertilizing may make the problem worse, by forcing top growth that cannot be

supported by the reduced root system.

(Joe Freeman is chief horticulturist at Cypress Gardens, near Orlando, Fla.

Anthony C. Bleach coordinates the landscaping and horticulture programs at

Naugatuck Valley Community-Technical College in Waterbury.)