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NURSERY |
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THE BASICS OF PLANTING TREES AND SHRUBS
Adding trees and shrubs to your landscape is an investment; not just a financial investment
but also one of time,planning, labor and often emotion. With all of the investment made even
before planting, it just makes sense to learn as much as possible about the care of your new
tree or shrubs.
PLANTING
Dig a hole no deeper than the plant root ball and 2 to 3 times wider. Fill the hole with water
before planting. It the water empties in less than 15 minutes, you have well draining sandy
soil. Refill the hole with water 3 to 4 times more. If water takes longer than 45 minutes
to drain, you have soil with clay. Don't add any more water until planting is finished.
Watering the hole prior to planting moistens the soil deeply and encourages deep,
drought resistant root growth. You have prepared the planting hole. Now you can start
planting. Remove the tree or shrub from its container and place in the hole. The top
of the soil of the root ball should be even with or slightly higher than the ground soil.
Adjust the hole depth as needed. Once the plant is properly positioned in the hole,
back fill with the soil you dug - do not amend the soil with compost (we will address
this later.) Leave a small depression around the plant and fill with water two to three
times. If the soil settles exposing the root ball, add more soil but leave the depression
to serve as a holding area for watering.
AMENDING THE SOIL
We don't recommend adding amendments to planting hole for trees and shrubs,
nor does the Master Gardener Program or the Royal Horticultural Society, among
others. Over a period of 50 years, we've learned that amending the planting hole
often inhibits the roots from growing out of the amended soil into the surrounding
soils, especially if the existing soil is very different from the amended soil - e.g.
heavy clay or sand. Nor will adding grit, sand or bark to the planting hole "open up"
clay soils.
To properly amend or open up existing soils for a tree, you would need to dig a
hole large enough for the root system of a mature tree - anywhere from 20-30'
wide by at least 10' deep for a medium size tree; 80-100' by 20' deep for a
large conifer. As well, amending the soil often makes the roots vulnerable to
tipping over in winds or to a general decline in health. Again, this reinforces
the idea of choosing a plant appropriate for your soils and site.
MULCHING
Small shrubs planted in the border are not as adversley affected by soil amending.
The best way to amend the soil is to apply a mulch over the planted surface and let
nature do the work of intermingling it with the existing soil.
SOIL TESTING
It is best to have your soil tested before planting a new area. Contact the
Master Gardeners Office or the Elisabeth Miller Library at the Center for Urban
Horticulture for information on companies who can test your soil. You'll learn any
fertilizer deficiencies or over abundance, pH and other important facts about your
soil. Amending without soil testing is like driving across the country without a
map - or a destination.
WATERING
Water all trees and shrubs well after planting, keeping them moist for the next
three years, not just summers but years. In the Puget Sound area we usually do
not have sufficient rainfall from April 1st through Thanksgiving to support new plantings.
Against houses, under eaves or on the leeward side of fences or neighbors' structures,
new plantings may need additional water during winter months, especially evergreens
which will shed water away from their root ball.
SPRINKLERS
shrubs. These systems tend to apply too little water for short periods causing roots
to rise to the surface in search of a meager 5 to 15 minute watering. On hot days
these roots dry and the plant becomes stressed or dies. Slow soakings by soaker
hoses or trickle systems are the best way to deliver water to the unestablished trees
and shrubs. Until the roots move out from the original root ball and down into the
surrounding soils, the trees and shrubs, like infants or young pets, rely upon you
to become self sufficient and established.
'How often should I water" is a common question and one difficult to answer.
There can be no set schedule. You water plants when they need it, keeping in
mind that trees and shrubs must not dry out for the first three years after planting.
On cool rainy days, the answer is "not very much or at all." When days are sunny
but under 72F watering every other day is probably sufficient - unless the plant it
large and lush which requires more water. Once temperatures climb above the
mid 70s and it is sunny, most newly planted trees and shrubs will need water daily.
Above 90F and you may need to water in the morning and in the evening.
Remember that slow deep soakings are best. Standing with a hose spraying at the
base of a tree for two or three minutes is functionally useless to the plant. The
gardener is the only one soothed in this situation.
The average tree or shrub doesn't need fertilizer. In many cases it can harm
the plant by creating too much soft growth vulnerable to insect and disease
attacks. A simple mulch of wood chips (not bark) or a mixture of compost and
sawdust/chips (no manures) placed around the root zone and just beyond the
drip-line of the plant is best.
The mulch should not be any thicker than 3 inches. Exceptions to mulching
are rhododendrons and Japanese maples. Their shallow root systems are easily
smothered. Apply mulch outside the drip-line of these plants, with just a dusting
beneath the canopy. The drip-line is the term used to define the outmost edge of
branches and thus the plant. This is usually where the feeder roots begin in the
ground, where they can catch rain and nutrients unblocked by the canopy of the tree.
Lawns, annuals some perennials and roses can require ferlitizer to support their
constant growth and flowering. The best fertilizers are formulated dry products
applied and worked into the soil. These formulated mixes are balanced for specific
plants and often contain micro-nutrients and elements needed by the plants and
soil microbiota. Using alfalfa meal, bone meal, or kelp - to name a few- alone will
not provide balanced nutrition to the plant.
Most plants respond well to annual compost mulching, but those which bloom
heavily from week to week need the extra boost of applied fertilizers to maintain
this flowering frenzy...along with deep soakings of water.
STAKING
Staking is rarely needed but it you do stake a tree or shrubs, stake it loosely
so the trunk can move with the breeze. This encourages strong root development.
Rigid staking inhibits the plant from creating a strong and stabilizing root system.
PRUNING
A tree rarely needs pruning unless a particular shape is desired or the canopy
need to be raised to expose the trunk. The general pruning rule is to remove
the three Ds: dead, diseased or damaged wood. Shrubs are different and may
respond well to many forms of pruning. Additionally, spring blooming shrubs like
forsythia, deutzia or philadelphus benefit from summer pruning soon after flowering
to remove the older flowering shoots to the ground. By doing this, younger stems
and the fresh growth sets buds for the following year. This also shortens the natural
height of the shrub. Instead of growing 8 - 10' tall a shrub may only reach 5-6'.
That said, pruning is not necessary - except for the 3 Ds.
SOILS
Learn your soil type: topsoil, sandy/gravelly, clayey, mixed up and compacted
from construction, or -the worst-a few inches of topsoil placed over clay, hard pan
or construction debris.
The first three are easy to plant in as long as you use plants adapted for those
soils. The latter two - mixed construction or topsoil over debris - are the most
difficult to garden with and to amend. Just placing a layer of top soil over the poorer
soils doesn't work. The two layers must be intermixed, otherwise water and roots
may not penetrate from the top to the lower layer. It's best to hire a landscaper
who can provide labor and machinery to effect better soil conditions, although hand
digging is a good option. In sandy soils remember to use drought tolerant plants.
Even if dressed with mulches sandy soils remain fast draining.
In soils which take 30 to 45 minutes to drain, most plants will do well.
The soil has organic components absorbing water which is what most plants want.
In soils that are clayey and take over 45 minutes to drain use clay and moisture
tolerant plants, which still may need supplemental watering during dry summers.
Clay soils tend to hold water while providing little air space --
even plant roots need to breathe. The soil is often full of nutrients but when once
dried out, it is very hard to rehydrate.
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