We often think about planting trees in the spring, which is definitely a good time, but fall is also a good time to plant and establish new or replacement trees. There are some advantages and cautions about fall tree planting that should be considered before getting started.
One main advantage of fall planting is that the soil temperatures are warmer and this encourages root growth more quickly as compared to cool spring soils. If the roots are able to grow quickly this also means that a fall planted tree is able to become established sooner than a spring-planted tree and will be more prepared for the heat stress next summer.
Here are some other tips for fall tree planting:
1. Make sure to plant at the correct time. If an evergreen tree or shrub is to be planted it should be by mid to late September. These plants ideally need at least 6 weeks to establish themselves before the first killing frost. If not established properly they can be subject to winter injury and desiccation from cold and wind. Deciduous trees (those that drop their leaves) may be planted later in the fall than evergreens but the benefits of warm soil and quick root growth are lost the later the tree is planted. Deciduous trees are less prone to winter damage but must still receive proper care to survive the winter.
2. For ball-in-burlap or containerized trees dig the hole two to three times wider than the rootball. Dig the depth of the hole 2 or 3 inches less than the height of the rootball. The first root (flare root) coming off the tree trunk should at ground level and no deeper. One of the most common planting mistakes is planting trees too deep. Once planted too deep, a tree grows slowly and has increased stress issues over its lifetime. As little as two inches too deep can cause issues. Always set the root ball on undisturbed soil. It is more important to dig a wider hole to loosen soil around the sides of the root ball because tree roots grow outward.
3. Deal with girdling or matted roots. Containerized trees may have circling or matted roots that will need to be shaved or cut to prevent girdling (roots growing around and damaging the tree trunk) later on. Girdling roots can be cut with pruners or a hand saw if needed. Stopping circling roots know will prevent major problems for the tree decades later.
Stem girdling roots – Fixing stem girdling roots is an important practice when planting woody plants. Heavily matted root systems of annuals and perennials also need to be addressed at planting for plants to perform their best. Even quick-growing annuals often fail to develop a good root system if circling roots are not teased out. Roots growing in a tight circle will continue to circle after the plant is in the ground.
Matted roots – If a plant’s root ball is matted with roots, either pull the root ball apart with your hands or make several cuts down the side of the root ball to loosen it. Pull the root mass apart and spread the roots out in the planting hole. Annual plants with a mat of roots at the base of the root ball also need attention. Tear the base mat of roots off or gently pull the root system apart so it can be spread out in the planting hole. Plants will quickly develop new roots.
4. Once the tree is in the hole and straight, backfill with the original soil. It isn’t recommended to add compost, peat, or other organic materials to the backfill. It is possible to amend the planting site, but amending only the planting hole can negatively influence water movement into or out of the root ball, and it does not help root establishment.
5. Mulching is highly recommended and will moderate soil temperature and moisture fluctuations. Be careful not to pile the mulch directly up the tree trunk itself since this can allow more points of disease entry and harbor bark chewing rodents like voles.
6. Trunk protection with a tree wrap or guard is recommended on newly planted trees to prevent freezing and thawing cracks that often occur in the bark during the winter temperature fluctuations. Staking may also be necessary for long or leggy trees.
7. Consistent watering will be a must for new trees. Trees should be watered on a regular basis during the remainder of the year. Frequently check the moisture status of the tree’s rootball. Water newly planted trees when the rootball begins to dry out but do not overwater. Continue watering until the ground freezes in winter and even during the winter at least once or twice a month on warm days to avoid winter kill.
Diagram of a properly planted tree
Practices that encourage growth
- loose/non compacted soil, proper irrigation
- mulch ring 8 feet in diameter or more around planting hole
- root flare slightly above soil surface (not planting too deep)
- leaving top of tree intact (no pruning at planting)
- proper staking (if needed)
- trunk protection (especially for thin bark on new trees)
- compacted soil
- little or no irrigation
- grass and weeds close to trunk
- planting too deeply
- heavy pruning at planting
Little or no effect
- peat or organic matter addition as backfill to the planting hole (can lead to problems with water moving in and out of the root ball and the tree settling too deep in the hole as the organic matter decays)
- root stimulant products
- fertilizing at planting (it is recommended not to fertilize until the tree has had a year to begin establishing roots in the new site)