There is no better time to plant trees and shrubs than fall. They won't make much visible growth in the cool weather and shortening days, but below ground their roots will be growing and establishing themselves in preparation for a strong season of top growth next spring. In contrast, planting in spring or summer can lead to a lot of leaf growth before a healthy root system is developed, causing withering in summer's heat when the insufficient root system can't pull in enough water.
Planting trees and shrubs is not rocket science and here are steps that will help you succeed.
Dig a Worthy Hole
Dig your hole to the same depth as the height of the root ball and 2 to 3 times wider than the root ball.
Pro-Tip: When planting in soil where water does not drain well, construct a raised bed first (or build up a low, broad mound of soil) and then dig your hole in the center of the raised area.
After the hole is dug, break up any lumps in the soil that was removed. This is easiest to do in a wheelbarrow.
Pro-Tip: If you add soil amendments, such as peat moss, compost or sand, it is best to only do so for the top third of soil going back into the hole. Otherwise the water will not move freely between the existing and newly modified soil, which hinders the newly planted tree or shrub.
The roots of the tree or shrub need to be moved from the circular shape they're forced to grow in by the pot—otherwise they may continue to grow in a circular shape, rather than spread outwards. If the roots are not very crowded on the edge of the root ball, simply scuff the soil slightly with your fingers to dislodge any small roots that are there. If the roots are extremely 'root-bound', it may be necessary to pry them loose with the tip of a trowel.
Place the root ball in the center of the hole and check that the top of the roots are even with the top of the surrounding soil.
Pro-Tip: Stand back and look at the plant in the hole before adding the soil. Adjust it so it is standing up straight. If one side looks nicer than the other, face the most attractive part in the direction where it will most often be viewed.
Add the soil back into the hole around the roots, compressing it slightly with your hands to eliminate any air pockets. Once the hole is filled, spread any remaining soil in a thin layer over the area surrounding the plant.
Care for the New Planting
The planting process is not complete without giving your new tree or shrub water. When doing a fall planting in an area where the soil freezes over winter, you may not need to irrigate again until spring, as long as the soil stays moist until it freezes. Continue to water the newly planted tree or shrub through dry spells, checking soil moisture every few days for the first month and then every other week for the first 2 years of growth. Check the soil moisture several inches down, within the root ball area of your tree, to determine when water is needed. Aim for the soil to be moist, but not soggy. Don't rely on lawn irrigation because the grass quickly takes up water for itself.
Finally, spread a layer of mulch over the planting area to conserve moisture and keep the weeds down. Do not place the mulch right up to the trunk, pull it away at least 2 inches, as it will slowly cause the bark to rot, eventually killing the tree.
Stake, Only if Needed
If you're planting a large tree (over 6 feet), in a windy or sandy location, this is the time to install stakes to prevent it from toppling over. Staking is only recommended for windy or very sandy locations. Allow for a bit of movement, as staking the tree too rigidly can inhibit the root development that naturally comes in response to trunk movement. Be sure to cushion any rope or wire where it comes in contact with the trunk to avoid damage to the bark. A staking arrangement should not be left in place for more than one year and should be checked frequently to assure it is in good condition and not damaging the tree.