A Great Season to Plant Trees
Autumn is a great time to plant new trees. The combination of cooler weather and autumn rains allow trees to establish new roots now and next spring before the summer heat and droughty conditions begin. Don't fear the winter: trees, including newly planted ones, go through a dormancy period and emerge ready to grow next spring.
Hotter summers and heavier rainfall events can mean trees provide greater benefits for your property. So, what do you need to do to plant a new tree this autumn?
Go Native
Native trees thrive in our climate, and they benefit birds and other local wildlife. No matter what kind of native tree you choose, note its maximum height at maturity. This ensures your selected planting location is ideal for the long term.
If you're concerned about wind resiliency, choose a tree that will be smaller at maturity or plan to plant a larger tree farther from your home. Locating trees in groups (groves) can also help them resist high winds.
Location, Location, Location
It's essential to identify good planting locations. If you plant a tree near the overhead utility lines, select a tree with a mature height that will be 25 feet or less. And don't forget about the underground utilities when considering a planting location for your new tree. Submit a request to missutility.net/homeowner so underground utility lines can be located and marked prior to tree planting to avoid planting near them.
Where do you want your tree? Plant it at least 15 feet away from your house so there's room for roots and branches to grow to maturity. If you want to save energy, locate the tree where it will shade your home during the hot summer months.
Dig Wide
Once you have purchased your tree, dig a hole two to three times the width of the tree's root ball and only as deep as the root ball. A wide hole encourages outward root growth and gives the young roots plenty of room to spread as they continue growing into the undisturbed surrounding soil.
Save the excavated soil from the planting hole to use as backfill around the root ball. If the existing soil is dense or rocky, it can be amended it with good topsoil or compost. If soil is dense (eg, clay), compost is a particularly good soil amendment to help improve the structure and loosen it up.
Remove the tree from the container before planting. Burlap and wire baskets should also be removed from the root ball prior to backfilling with soil. Cut off any tags and string carefully to avoid damaging the tree. If the root ball of a containerized tree has circling roots (ie, is rootbound), cut the circling roots around the sides and the bottom. Don't fret about breaking these circling roots; doing this will encourage outward root growth, which will help to stabilize the new tree.
Plant It High
Carefully inspect the tree trunk to locate the root flare, which is the swollen area at the base of the trunk where the root area begins. Remove excess mulch or soil from the top of the root ball to expose the tree trunk root flare to determine the correct planting depth. Place the tree in the hole so that it rests on firm soil and the root flare area at the base of the trunk is about an inch above ground level. Ensure the tree trunk is straight; once the roots start growing, you don't want to find you have a crooked tree.
Begin backfilling the hole around the root ball with amended soil about one-third up to ground level and add some water to settle the backfilled soil. Continue backfilling the hole the rest of the way, tamping gently to remove air pockets and adding more water to settle the soil again. The soil should be moist, not flooded with water.
It's not necessary to stake the tree; unstaked trees develop stronger and more quickly. However, if tree trunk protection is needed from lawn mowing equipment, consider installing a section of corrugated drainage pipe at the base of the trunk or protection stakes that are not attached to the tree.
If deer frequent your property, it is also wise and economical to protect tree trunks from deer rubbing with a flexible plastic or wire mesh tree guard.
Don't Forget the Mulch
Mulch holds in moisture, moderates the soil temperature, and reduces competition from grass and weeds. Add 2 to 4 inches of mulch on top of the backfilled hole but keep mulch 1 or 2 inches away from the trunk, to prevent trunk decay. A mulch berm created at the outside edge of the planting hole will help to retain water in the root ball area.
Visit Your Tree
Visit your new tree at least once a week to ensure the soil is moist. If it's dry, water moderately across the mulched area (ie, not just at the trunk). Trees planted in autumn often receive adequate rain, and once the soil freezes in the winter, no watering is needed. Once your tree buds in the spring, start checking it again weekly and water as needed to keep the soil moist.
A watering bag or ring that releases water slowly is not typically needed for autumn-planted trees but will help keep your young tree watered through dry periods the following summer.
From the City's Tree and Landscape Board