Michigan State University Extension
MSU Extension Forestry Bulletins - FTE77101
01/03/01
Douglas O. Lantagne
and
Melvin R. Koelling
Department of Forestry
Michigan State University
Each year trees are planted on several thousand acres
of Michigan land. Most are planted on cutover forest land
or abandoned agricultural fields, and more recently on
highly erodible agricultural land covered under the
Conservation Reserve Program.
Trees are planted for many purposes, including timber
production, wind-breaks, erosion control, Christmas tree
production,wildlife habitat improvement, future investment,
aesthetics and other landowner objectives. Tree plantings
enhance the natural beauty of the state, protect
watersheds, and enable forests to contribute to the state's
economy by assuring a stable supply of wood and providing
for recreational opportunities.
Each year many trees are planted by private forest
landowners. Often these individuals are unfamiliar with
planting techniques that will assure high survival and good
growth. To have a successful tree planting program,
particular emphasis must be given to soil and species
selection, soil preparation, nursery stock selection and
handling, planting technique and follow-up care. Each of
these aspects of tree planting is discussed in this
bulletin.
Planting Considerations
Species and Soil Selection
Many trees grow under a wide range of environmental
and soil conditions, but best growth in most trees is
attained within a rather narrow range. Tree species
should be selected for their ability to grow on the
proposed planting site. Not all trees perform
satisfactorily on all soils, although they may grow well on
different soils in the same area.
Tree species planted on unsuitable sites suffer high
mortality, grow poorly and are more susceptible to insect
and disease problems. To help insure a successful
planting, evaluate the soil-species combination be-fore
trees are purchased and planted. Recommendations for
coniferous species for various Michigan soil-soil
conditions are discussed in Extension Bulletin E-721,
"Selecting Coniferous Planting Stock for Michigan Soil
Management Groups". Important soil and site factors
include air temperature(average, minimum and maximum), air
drainage, wind exposure, soil moisture, soil drainage, soil
texture and soil fertility. As a general rule, hardwood
species are better suited to loamy and clay loam soil types
where soil moisture and fertility are generally higher.
Although conifers will grow on heavier soils, they are more
commonly planted on drier, coarser textured, and less
fertile soils. All things considered, tree growth is most
rapid where soil drainage is good and competing grasses and
weeds are controlled.
Table 1 contains a list of tree and shrub species
suitable for planting in different parts of Michigan. A
brief description of some of the commonly planted species
follows.
Pines
Red pine is the most extensively planted reforestation tree
in Michigan. It has a high survival rate, grows well on a
variety of upland soil types and is relatively free of
serious insect and disease pests.
White pine grows well on well-drained sandy loam or
clay loam soils, but it is not well suited to dry soils.
It is susceptible to both white pine blister rust and white
pine weevil. The former is a canker disease that often
kills the tree. The latter,more of a problem in the
northern part of the state, causes bushy growth or crooked
stems by attacking and killing the growing terminal leader
and branches. Nevertheless, white pine is a fast growing
tree that does well on good soils in the southern part of
the state.
Jack pine is well adapted to growing on droughty,
infertile sandy soils. It is often planted on sandy
cutover sites where other trees do not grow or grow poorly.
Recently it has been planted in several northern Lower
Peninsula counties to create nesting habitat for the
endangered Kirtland's Warbler.
Scotch pine is extensively planted for Christmas tree
production. Because it is highly susceptible to insect and
disease damage, it is not recommended for reforestation
purposes. Older Scotch pine plantations found in Michigan
generally originated as Christmas tree plantations, but
were abandoned over time. Today,these plantations act as
a breeding ground for many tree insect and disease pests.
Extension Bulletin E-1155 entitled"Recommended Species for
Christmas Tree Planting" lists several recommended seed
sources of pine, spruce and fir species which are planted
for the production of Christmas trees in Michigan.
Spruce
White, black and Norway spruce are well suited to
fairly acid clay loam soils. Do not plant them on dry
upland soils, especially in the southern part of the state.
Black spruce is preferred for planting on poorly drained or
wet soils, particularly in the northern part of the state.
White and Norway spruce can be planted for Christmas tree
production on cooler, more moist north and northeast facing
slopes with fine to moderately coarse textured soils.
White spruce plantations for timber production are also
planted on some soils in the Upper Peninsula.
Blue spruce is extensively planted for Christmas tree
production throughout the state. As with Scotch pine,
there are several seed sources available for planting which
are described in Extension Bulletin E-1155. Blue spruce
grows best on well drained fine textured soils, although it
is adaptable to a wide range of soils.
Firs
Balsam fir, Fraser fir and Douglas-fir are planted as
Christmas trees on well drained, fine textured soils
similar to those used for spruce. Balsam fir and Douglas-
fir often have new growth killed back by late spring
frosts. Plant fir species on protected upland areas to
ensure proper air drainage and to minimize frost damage or
winter kill. Fraser fir and Douglas-fir are more
susceptible to injury from very low temperatures than
Balsam fir. In many areas of the northern Lower Peninsula
and in the Upper Peninsula, Balsam fir is recommended.
However, take care not to plant Balsam fir in areas with
a high concentration of spruce budworm. Fraser fir is
less susceptible to spruce budworm damage.
Hardwoods
Hardwood plantations are typically more difficult to
establish than conifer plantations. In general, hardwoods
require a more fertile soil than conifers. Preferred soil
textures include sandy loams, loamy sands, loams or clay
loams. Because fertile soils typically have higher levels
of grass and weed competition, intensive weed control is
required to successfully establish hardwood plantations.
Hardwoods may also require protection from rodents and may
need corrective pruning to produce quality trees.
Hardwoods planted most often are black walnut,oaks,
maples, poplars and ashes. In addition to timber value,
hardwood plantations can be designed for wildlife habitat,
aesthetics, windbreaks and firewood production.
Mixed Species Planting
Special emphasis must be given to species selection in
mixed plantings. Differences in species survival, growth
rate, shade tolerance, and soil-site requirements are often
responsible for uneven and unsatisfactory plantation
development. While mixtures of hardwoods are generally
compatible, conifer-hardwood and conifer-conifer mixtures
usually do not develop good timber stands, although they
are satisfactory as aesthetic or wildlife plantings.
In most mixed species plantations, weed control is
difficult and often restricted to mowing. Many of the
registered herbicides do not control undesirable woody and
herbaceous competition in mixed conifer-conifer or conifer-
hardwood plantations without damaging or killing one or
more of the planted tree species.
Examples of successful hardwood-hardwood plantations
include autumn olive with any other hardwood species and
black locust/black walnut plantations. Autumn olive and
black locust stimulate self pruning of the hardwoods with
which they are planted. Furthermore, since both are
legumes, they release nitrogen into the soil. Autumn olive
is also a food source for wildlife. Black locust will
produce firewood. The combination of these species with
higher value species, such as red oak and black walnut,
reduces establishment costs because fewer of the more
expensive oak and walnut trees are needed to plant the
site.
Planting Season
Bare rooted seedlings and transplants must be planted
during the dormant season if good survival is expected.
Weather and soil conditions conducive to planting occur in
both early fall and late spring. The spring season is
generally considered the best time to plant, especially if
planting is to be done on heavy loam or clay soils. Trees
planted on heavy soils in the fall are susceptible to frost
heaving and winterkill from dry winter winds. Winter
damage from rodents and other wildlife is also greater in
fall-planted than spring-planted trees.
Start spring tree planting as soon as the soil is free
of frost. Do not plant when the soil is excessively wet,
or on hot, windy days. Dull, overcast, cool days are most
favorable since evaporation and moisture loss from the
planted trees is reduced. However, trees planted in the
spring are susceptible to drought.
Tree Spacing
The distance between planted trees is determined by
the species and the purpose of the planting. The goal is
to plant a sufficient number of trees to fully utilize the
site, but provide sufficient growing space to avoid a
noncommercial thinning to maintain plantation vigor. No
single spacing is ideal for satisfying all planting
objectives. A distance of 6 to 12 feet between trees
within planting rows will result in maximum growth and
maintenance of tree quality for most species. Spacings of
less than 6 feet require thinning before the trees are of
commercial size and value and are not recommended. Tree
spacings greater than 12 feet are also not recommended as
the site is not fully utilized while the trees are young
and weed control problems are prolonged.
Wide spacings also contribute to the development of
trees with large branches and poor form. In general,
hardwood seedlings are planted at wider spacing than
conifer seedlings or transplants and are pruned to produce
high quality stems. Access roads should be evenly spaced
throughout a newly established plantation to facilitate
future management.
General planting density recommendations for specific
planting purposes are in Table 2. Typical tree spacing to
reach recommended planting densities are listed in Table 3.
Table 2: Tree Planting Density recommendations for common
planting purposes.
Conifers for Timber production 600 to 1000 per acre
Christmas trees 1200 per acre
Hardwoods 300 to 500 per acre
Windbreaks 3 staggered rows
Table 3: Common tree spacings used to reach recommended
planting densities.
Distance apart Number of trees per acre
6 X 6 1210
6 X 10 726
7 X 7 889
7 X 10 622
8 X 8 681
9 X 9 538
10 X 10 436
12 X 12 302
8 X 10 spacing is used to establish windbreaks and
shelterbelts in three staggered rows.
In general, rectangular spacings are advantageous
because they require fewer passes over the site with
planting or tending equipment, and they create corridors of
access for future operations. Rectangular spacings are not
recommended for wildlife and aesthetic plantings.
Site Preparation
Site preparation reduces vegetative competition,
reduces any logging debris left on the site, and improves
soil conditions for tree growth. Several different
procedures may be used. Furrowing or scalping, usually done
with an attachment on a planting machine; plowing and
discing, and herbicide treatments are all used to eliminate
or reduce vegetative competition. In all cases, except
scalping and furrowing, site preparation should occur in
the year before planting.
Although furrowing does provide short-term vegetation
control, it creates other problems. The most important is
the loss of fertile topsoil from the immediate vicinity of
the tree roots. The trees are generally planted in the less
fertile sub-soil after the surface layer is scalped.
Furrows also encourage soil erosion on sloping sites and
provide natural runways for rodents that feed on the stems
of newly planted trees. The physical presence of the
ridges caused by scalping also creates problems for workers
and machines in future years.
Herbicides are often used in combination with
furrowing and plowing and discing to provide longer-term
control of vegetative competition. If herbicides are
correctly selected and applied, they are usually more
effective in controlling competing vegetation and more cost
effective than mechanical means. Many herbicides are
labeled for weed control in forest and Christmas tree
plantations. Several are described in the North Central
Regional Extension Publication #251, "Effective Use of
Herbicides in Christmas Tree Plantations". Contact your
local county extension office for this bulletin or any
additional assistance concerning herbicides.
Planting Stock
Types
Planting stock is available in a variety of species,
sizes and ages. Seedlings usually are described as 1-0,
2-0 and 3-0. The first number refers to the number of years
grown in a nursery seedling bed and the second to the
number of years in a transplant nursery bed. Seedlings may
be bare-root planting stock or container grown stock.
Transplants are commonly designated as 2-1, 2-2, and 3-2.
The total age of the plant is the sum of the two numbers.
For example, 1-0 refers to a 1-year old seedling and 2-2 to
a 4-year old transplant.
Transplanted stock is more expensive than seedlings,
but survival and growth after planting are often better.
The improved survival and growth is attributable to the
more thick and fibrous root system on transplanted planting
stock. Order spruce, fir, and Douglas-fir as transplant
stock to help insure planting success. For most pines,
standard 2-0 stock is
usually satisfactory.
Some seedlings and transplants are sold by height
class. This has the advantage of establishing a plantation
which should develop uniformly. This is important for
Christmas tree plantings where uniform growth is desired.
Available sizes may range from 6 to 12 inches. A rule-of-
thumb for planting success is to buy the biggest or oldest
seedlings you can afford. In all cases avoid small (less
than 6" tall) spindly planting stock. For hardwoods, look
for seedlings with at least a 3/8 inch caliper and at least
six vigorous lateral roots. Avoid hardwood stock with a
single large taproot.
In the past several years, container grown seedlings
have be-come more commonly used for establishing
plantations in Michigan. Container seedlings usually are
grown in a greenhouse to reduce the time necessary to
produce a seedling or transplant. Depending on the
species, container grown seed-lings often are ready for
outplanting into a nursery bed or plantation in less than
a year.This compares to the 2, 3 and 4-year old trees
produced in standard outdoor nurseries. For most species,
seedlings are started in containers in the greenhouse and
then transplanted and grown for an additional time in
regular nursery beds. If the seedling remains in the
nursery bed for one year it is referred to as a plug-1
seedling. A plug-2 seedling remained in the nursery bed for
two years. This practice reduces the amount of time to
produce stock for these tree species and results in a plant
with abetter root system.
Container grown seedlings experience less shock than
bare-root stock at planting time because the seedling roots
are not disturbed when outplanted. Containers come in
various sizes to accommodate the rooting habit of the
species being grown. Conifer shipping containers may hold
2 to 4 cubic inches of soil compared to upwards of 75 cubic
inches of soil in large containers used for taprooted
hardwood species such as walnut and oak. Again, avoid
planting small container-grown trees.
Order planting stock well in advance of the planting
season to insure availability of correct species, size and
quality. Many of the nurseries which produce Christmas tree
seedlings and transplants are sold out of preferred
planting stock the summer before the planting season.
Planning is important and essential to a successful
planting season.
Characteristics
Inspect tree quality before accepting of seedlings or
trans-plants from the seller. Tree seedlings and
transplants are typically packaged and shipped in rolls or
boxes. Inspect boxes and rolls for crushed appearance and
coolness. Ideal examples of conifer and hardwood planting
stock should be inspected for:
- healthy green color
- fibrous root system and/or many lateral roots
- good stem caliper (diameter)
- single versus double stems.
Improper processing and/or handling of high quality
planting stock by the nursery, or poor handling after
purchase by the buyer, can reduce the quality of seedlings
and transplants significantly. Reduced quality in turn
means lower plant survival and slower growth. The
following are signs of poorly handled planting stock:
- dry roots
- white root tips
- excess soil on roots
- swelled or burst buds
- presence of mold on needles or stems
- physical damage (broken stems, root stripping)
- ripped or crushed bags and boxes.
Transporting and Storing
Improper care of planting stock upon receipt often
contributes to poor survival and growth of trees. To
curtail damage to planting stock follow these
recommendations:
- Never expose shipping containers to direct sunlight.
- Keep the temperature of the shipping containers near 35
degrees F during transport.
- Don't stack shipping containers during transport or
storage.
- Keep one side of each container exposed to open air.
- Do not allow containers to touch.
- Transport and store containers on pallets.
Good air circulation and careful handling are important
steps in the maintenance of seedling or transplant vigor.
Best planting success occurs when the seedlings or trans-
plants are planted as soon as possible after arriving from
the nursery. If planting is delayed, keep the plants cool
(35 degrees F) and moist. Make sure that roots are moist
and that drying does not occur during storage. Store
containers on the north side of a large structure, under
dense groves of conifers, in shaded snowbanks, in root
cellars or other cool, moist locations. Make sure that
reflective tarps or other covers placed over the containers
allow air circulation and provide shade. Spray containers
with water if the temperature rises above 40 degrees F.
How To Plant
Seedlings and transplants may be successfully planted
by either hand or machine. Where conditions are favorable,
machine planting reduces both time and labor. On
particularly steep,rough or stony areas, or for
interplanting between established trees, hand planting is
often the only practical method. Handplanting is also
somewhat better suited for planting certain hardwood
species, such as walnut and various oaks, which have long
taproots.
Handling Planting Stock
Bring only the number of trees necessary for a single day
of planting to the planting site. Moisten planting stock
containers before they are removed from the storage area.
Shield containers from the sun during the trip to the
planting site. At the planting site, immediately place
planting stock in a shady location. If necessary, use a
vehicle to construct a lean-to for shade. Open only one
container at any one time, and close it after the necessary
bundles of trees have been removed. This prevents the
remaining trees from drying out or overheating. Never sit
or place heavy objects on containers so that seedlings are
not crushed and damaged.
Carefully separate the seedlings or transplants in the
extracted bundles to minimize the number of stripped or
broken roots. If the roots of the trees were not pruned to
an 8 inch length at the nursery, do so before planting with
clippers, sharp axe, machete or hatchet. Root pruning
makes planting easier and increases survival rates. The
actual root length can vary to accommodate the planting
tool being used. In general, the depth of the planting
hole and the root length should be the same, but not less
than 8 inches.
Keep the tree roots moist and protected from the sun and
wind while handling. However, it is usually not
recommended to soak the tree roots in water before planting
because protective soil particles are removed from the
roots, making the roots more susceptible to drying. Place
planting stock in white containers containing either moss
from the shipping container, wet shredded newspaper, wet
burlap or other similar material. This prevents the tree
roots from drying out while planting. These materials
should also be used in the tree holding boxes on planting
machines. No more than one to two hours worth of trees
should be carried by the planter.
Hand Planting
There are two general methods of hand planting: the
hole method, and the bar or slit method.
The hole method consists of digging a small hole in
the soil to hold the roots of the tree. The hole is made
large enough for the planter to spread the tree roots out
in a natural uncrowded or twisted position. Soil is then
added around the roots and tamped firmly to exclude air.
Some variations of this method involve the use of a mattock
or shovel to make a straight sided hole. The tree is then
placed along this straight side and the soil replaced. The
soil is then tamped.
Seedlings or transplants can also be planted by making
a vertical slit in the soil, inserting the roots of the
plant and re-closing the slit, both top and bottom. It is
important that the tree roots are not crowded and the soil
is firmly replaced around the roots. Roots should fall
down in the hole to avoid the deformity called J- or L-
rooting. Seedlings with J-roots are more susceptible to
drought, disease and insect attack because the root system
never develops properly. Root systems with a
characteristic J or L shape are typically caused by not
making the planting hole deep enough or twisting the tree
into the hole.
Machine Planting
A planting machine is attached behind a tractor and
creates a slit in the soil as it is pulled along. The
seedlings or transplants are placed in the slit. A set of
wheels on the back of the planter close the slit and pack
the soil around the tree roots. Many types of machines are
available, and each has some special advantage. Some are
equipped with furrowing attachments to clear away competing
vegetation.
Others have spray attachments to apply chemicals for
controlling weed growth around newly planted trees.
Planting machines are very helpful and efficient when
planting large areas. During operation, check them
occasionally to make sure trees are being planted at the
correct depth and that the soil is being packed firmly
around the roots. Changes in soil type and topography also
may call for minor adjustments in the machine planter.
Summary of Planting Rules
- Plant trees one inch deeper than they were in the
nursery.
- Plant trees upright, not at an angle.
- Plant trees in mineral soil, not in loose debris.
- Pack the soil firmly around planted tree roots.
- Keep tree roots cool and moist.
- Do not plant in excessively wet or sticky soil.
- Plant tree roots in a natural uncurled position.
- Make the planting hole deep enough to fit the roots.
- Remove or suppress competing vegetation on the
planting site.
- Remove trees one at a time from the planting
container.
- Do not remove trees from the planting container
until the hole is prepared.
Follow-up Care
Plantation care after planting usually consists of
eliminating weed competition and protecting the plantation
from fire,grazing, rodents, diseases and insects. Early
plantation care, especially vegetative competition control,
determines whether trees will survive and influences the
eventual success or failure of the plantation. The
development of trees with poor form, or with slow growth
rates, is often the result of too much vegetative
competition for soil moisture and nutrients. Weed control
often means the difference between success and failure of
the plantation.
Weed control can be accomplished by mowing,
cultivation or chemicals. The first two require multiple
treatments during each of the first three to five growing
seasons. Herbicides, depending on the tree species
planted, can often be used to control unwanted vegetation
for one or more growing seasons in a single application.
Contact your local county extension office for more
information on herbicides.
Occasional examination of the trees for off-color
foliage, needle drop, and broken or consumed foliage will
help determine if insects and/or diseases are present.
Once detected and identified, chemical or other types of
control measures may be needed to prevent serious damage.
Obtain assistance on insect and disease identification
from your local extension office.
Special Considerations
Trees and forests greatly contribute to the quality of
our environment. Therefore, many individuals plant trees
for purposes other than producing forest products. Some of
these purposes are wildlife habitat, Christmas tree
production and aesthetics.
Wildlife Habitat
Many kinds of wildlife depend on the cover, food and
environment trees provide. In fact, the amount and
diversity of wildlife in many areas is determined by the
amount, type, variety and extent of local forest
conditions. Large and varied wildlife populations are not
found in barren areas, nor are they found in large, old-
growth forests. In general, the greater the variety of
plant species and the greater the variety of plant sizes
and ages, the better the habitat for a wide variety of
animals and birds.
Plantings for wildlife need not be large. Actually,
they are of highest value when planted in scattered
groupings throughout a property. Leave open spaces and use
irregular shapes in plantings. Plantings of a single
species are not as valuable as mixed group plantings which
contain hardwoods, conifers, and food-producing shrubs.
Wildlife packets, containing a variety of tree and shrub
species, are available from many local soil conservation
districts. The composition of the packets is
varied to match the location in the state where they will
be planted.
Christmas Trees
Michigan produces about one of every five plantation
grown Christmas trees in the United States. Growing
Christmas trees has become a highly intensive business that
requires significant knowledge, time and effort on the part
of growers.
Christmas trees require consistent monitoring and care
after planting. They require annual shearing, beginning in
the third or fourth year, and protection from insects and
diseases each year.
Several species of conifers are used as Christmas tree
stock. The most common are Scotch pine, Colorado blue
spruce, and Douglas-fir. For more information on growing
Christmas trees,contact your local county extension office.
Aesthetic Considerations
Trees and forests are important to the quality of the
environment. Tree cover moderates air temperature,
suppresses noise, collects dust, dissipates odors, balances
carbon dioxide and oxygen levels, and can even warn of
dangerous levels of air pollution.
When planting trees to improve aesthetics, it is well
to plan for future growth of the trees. Mixing species,
such as conifers and hardwoods, lends to diversity.
Planting low growing and tall trees in different locations
adds contrast. Consider tree form, flowering habits,
foliage patterns, and fall colorations when planting
selections are made. Many of these features will increase
the attractiveness of any planting in later years. In
congested urban areas, select trees that posses some
tolerance for confined conditions, and are resistant to
certain pollutants. In all plantings, consider soil
properties, water availability,space and nutrient
requirements before selecting and planting trees. Consult
your local county extension office for further information
on how to select the right tree species for your situation.