The proper installation of plants in the landscape involves much more
than just digging holes and setting plants in them. The existing soil
is often compacted and poorly drained. Tilling or digging to improve aeration
and drainage is essential for satisfactory plant growth.
The current trend is to plant trees and shrubs in large beds. Preparation
of an entire bed is preferred over preparing individual holes since the
roots will have a larger area to grow before they encounter native soil
that might be compacted and poorly aerated. To achieve a 25 percent increase
in organic matter, incorporate 3 inches of organic matter, such as pine
bark mulch or compost, into the top 12 inches of soil. The organic matter
used should be composted or aged. Incorporating uncomposted organic matter
can create nutrient deficiency problems. Adding organic matter when preparing
individual holes is not recommended.
Plants can be purchased as bare-root, ball and burlapped (B&B), or
as container-grown plants. Planting procedure varies somewhat with each
Planting container-grown plants
Container-grown plants have become the most popular method of growing
plants for sale by the nursery industry. In theory, container-grown plants
can be transplanted year round, however, extra attention to watering must
be made when transplanting in late spring or summer. Late fall and early
spring are considered ideal planting times because roots will have more
time to grow into the surrounding soil before the stress due to new foliage
growth and high temperatures occurs.
The planting depth should be such that the plant is exactly the same depth
after transplanting as it was in the container. Ideally, the hole should
not be dug any deeper than the root ball. The loosened soil below the
root ball can settle resulting in the plant being planted too deep. If
you dig too deep, firm the bottom of the hole to reduce settling. Since
most new roots will grow horizontally from the side of the root ball,
soil firmed at the bottom of the hole will not substantially affect root
growth. In most compacted urban soils, root growth from the bottom of
the root ball will be limited by inadequate aeration and possibly excessive
moisture. In some cases the roots in the lower portion of the root ball
die after transplanting. Efforts to improve the soil should be directed
near the soil surface by preparing the entire bed or digging wide individual
Widening the planting hole is an ideal way to enhance plant growth. A
planting hole that is three times the width of the root ball with the
sides of the hole sloping towards the bottom is ideal in most situations.
When digging in heavy soil the sides can become slick especially if the
soil is somewhat wet. Slick sides can act as a physical barrier to root
growth and moisture movement. Use a shovel to make the sides of the hole
rough and irregular.
Always water plants thoroughly before transplanting. Remove the plant
from the container by turning the plant upside down and giving the top
edge of the container a sharp rap. Catch the root ball in your hands as
it slips from the container. If plants have become overgrown in the container
and the root mass is growing in a tight, compact circle the roots should
be loosened before planting. If the roots are only slightly encircled
you can loosen and spread them out by hand. Many gardeners cut the outer
roots with a sharp knife by making vertical cuts approximately 2 inches
into the root ball on two to four sides of the root ball. Some gardeners
split the lower half of the root ball and spread the roots horizontally.
This practice raises the lower roots closer to the soil surface. Plants
such as azaleas, rhododendrons, and daphne that are especially prove to
developing root rot in poorly drained sites could benefit from this butterflying
practice. After the roots have been loosened or cut, carefully place the
plant in the hole. Always pick the plant up by the root ball never by
the trunk or stem (can cause damage to fine root hairs).
Soil that was removed from the hole should be used to refill the hole.
Traditionally, the recommendation was to incorporate organic matter into
the backfill (soil used to fill a planting hole). Some gardeners took
the practice further and completely replaced the removed soil with purchased
topsoil. Research has shown neither practice helps plants grow and in
some cases can be detrimental. When water enters soil with one type of
texture and later comes in contact with soil that has a very different
texture water movement (drainage) is impeded. Excessive water can accumulate
in the bottom of the hole which can lead to root suffocation or root rot
development. Some researchers report that amended backfill can cause roots
to remain in the planting hole instead of growing into the surrounding
soil (roots will grow in the area of least resistance and greatest soil
aeration). The primary reason for digging a wide hole is to improve soil
aeration and to reduce compaction.
Lime should be mixed with the backfill, if needed, based on a soil test.
Fertilizer should not be added at planting since it can burn the roots.
An exception would be the application of phosphorus which moves very slowly,
or not at all, in the soil and plays a key role in root formation. It
will not burn the roots. Liquid fertilizers are some times applied after
planting, but their benefit has not been proven.
Fill in around the plant with soil until the hole is one-third full. Firm
the soil around the root ball, however, be sure not to use excessive force
since soil compaction should be avoided. Loosen and break up any clods
of soil before backfilling. Clods can create air pockets around the root
ball. Before finishing the filling process, make certain the plant is
straight and at the proper planting depth. It is important when planting
(particularly container-grown material) to avoid covering the top of the
root ball with more than 1/2 to 1 inch of fine soil. Ideally it should
be level with the soil surface. Otherwise, water can be diverted sideways
through the native soil and not soak down into the root ball where it
After a tree or shrub has been planted, construct a ring of soil 2 to
3 inches high to form a water basin at the outside edge of the hole (plants
in beds probably will not require a water basin). This permits water to
go into the root zone rather than running off the surface. Water the plant
to eliminate air pockets around roots. The water basin does not need to
be a permanent fixture and can be removed after the plants become established.
Apply a 3-inch layer of mulch over the planting hole. The mulch will help
maintain moisture and reduce fluctuations in soil temperature. The mulched
area should be expanded as the plant grows.
Planting bare-root plants
Bare-root plants are usually the most economical form of plants but require
more care after planting. These plants were grown in a field nursery and
dug during the dormant season. Soil was removed from their roots before
they were put into cold, moist storage. At shipping, the roots are covered
with damp peat moss or sawdust, wrapped with plastic, and placed in the
mail. Few evergreen plants are sold bare-root; most are deciduous trees
or shrubs. Plants with a long tap root, such as nut trees and some fruit
and shade trees, are often sold bare-root because they are not adapted
to balling and burlapping or container production. Mail-order companies
often sell bare-root plants because it is more economical to ship plants
without soil. Some retailers carry bare-root plants packaged in cardboard
containers with roots wrapped in damp sphagnum. Occasionally bare-root
plants are potted into containers and misleadingly offered as container-grown
Bare-root plants should be planted while they are dormant. Fall planting
is well-suited for these plants. However, many mail-order companies do
not ship until spring.
When plants arrive in the mail check them for moisture. Never let the
roots dry out. Keep the roots wrapped in wet paper or sphagnum moss and
covered with plastic until you are ready to plant. Keep the plants in
a location with cool but above freezing temperatures; roots can be easily
damaged by freezing temperatures.
Before planting the roots should be soaked in water for at least an hour
but not more than 24 hours. Longer soaking can drown the roots from lack
of adequate oxygen. Prune off any broken or damaged roots before planting.
Never leave the root exposed to wind and sun even during the planting
process; keep the roots protected by wrapping in moist burlap or place
them in a bucket of water. Build a mound of soil in the center of the
planting hole and spread the roots around it. With bare-root plants, the
soil should be worked gently in and around the roots while the plant is
being supported to ensure good soil-root contact. Water to eliminate air
pockets. Bare-root plants may need some light pruning after planting.
Planting balled and burlapped plants
Balled and burlapped plants have been grown in field nursery rows, dug
with soil intact, wrapped with burlap, and tied with twine. The size of
the root ball will vary with plant size. The diameter of the root ball
should be 10 to 12 times the diameter of the tree trunk measured 6 inches
off the ground. Most of the plants sold as balled and burlapped (B&B)
plants are large, evergreen plants and deciduous trees. They transplant
best during late fall and early winter but can be successfully done in
the spring. Some field-grown plants are being produced in fabric bags.
They are handled essentially the same as B&B plants except the fabric
bag should be removed at planting.
Many B&B plants are root pruned in the nursery so the root system
will be more compact and fibrous. Even with the best nursery efforts,
many (up to 95 percent) of the roots are lost in the digging process.
The remaining small portion of the plant’s former root system can
have difficulty absorbing enough water to meet the plants needs.
When selecting a B&B plant, be sure the ball is sound and hasn’t
been broken. Avoid plants that feel loose in the soil ball. B&B material
must be handled carefully. On most species if the soil ball is broken,
many of the small roots will be severed from the trunk and the plant will
die. Always pick the plant up by the soil ball --- never by the trunk
or stem. Be sure the soil ball does not dry out or is exposed to hot summer
or freezing winter temperatures for an extended period of time before
The planting procedure is essentially the same as for container-grown
plants. The burlap should be left on the root ball unless it was made
from a synthetic material or has been treated with a chemical preservative.
To determine the difference between natural and synthetic material hold
a match to a small portion of the burlap. Natural material will burn while
synthetic will melt. Untreated natural burlap has a tan color and is biodegradable.
The burlap on top of the root ball should be cut, rolled back, and covered
with soil. If part of the burlap is exposed above the soil line it can
act as a wick that will remove moisture from the root ball.
After positioning the plant in the hole, remove any straps, ties, strings,
or wires secured aroun the root ball. Wire baskets are often used to reinforce
the root ball during shipping. Experts disagree on possible harm that
the wires might cause if left in the planting hole. It might be safer
to cut and remove the top portion of the basket. Removing the entire wire
basket can cause the root ball to be damaged. B&B plants usually need
little pruning at planting but may need careful watering during the summer.