When should you plant new trees? Many people plant in spring, probably because they want to do some gardening at that time of year. Others claim that fall planting is better. Here is what the experts say.
When Do Landscapers Plant Trees?
Landscapers should know the best time for planting trees so it might make some sense to look at what they do. Around here, zone 5, companies are planting trees almost any time of year, except in the dead of winter. I think this has more to do with the need to complete projects than what is best for the trees.
A new local grocery store was landscaped on the hottest days of the summer. The next day, the shrubs looked like they were dead. They have since come back mostly because they are a very hardy variety of dogwood.
Along the road near where I live they are still planting trees at the end of November with frost in the ground and snowing.
Neither of these are good examples of when to plant trees. However, it always surprises me that some trees and shrubs planted this way do survive.
This blog assumes that you are planting in a cold climate where you do get frozen ground during part of the year. In warmer climates the time for planting is not as critical provided you can provide adequate water.
Planting Trees in Spring
Spring seems like a good time for planting trees. Nurseries have the biggest selection at this time of the year so it must be the best time to plant, or else why would they have all these trees available?
Planting in spring gives the tree a chance to grow all summer and get ready for winter. Soon after planting, leaves develop and they are able to make food for the plant all summer. Keep in mind that we only see what goes on above ground. When a tree is planted it needs to make new roots. Planting in spring means that the tree needs to make new roots at the same time as it makes new leaves. Both of these growth processes require sugar reserves that are stored in the roots, and stems. Trying to grow both leaves and stems at the same time is taxing for the plant and both processes can suffer.
This growth not only requires sugars, but it also requires a lot of water. With a limited root system, the plant can have problems getting enough water. This is why some newly planted trees drop some or all of their leaves shortly after planting. They just can’t suck up enough water to support all of the leaves.
Planting Trees in Fall
Many experts claim that planting trees in fall is better. In fall, the tree can make new roots without having to feed the leaves. Water requirements are much lower without the leaves on the tree. To us it feels cool in fall, but that is actually the best temperature for root growth. Roots grow best in cool soil.
A fall planting allows the tree to grow roots in fall and again early spring before leaves develop. This gives the tree a good chance to lay down a good set of roots before they need to collect water and nutrients for the leaves.
What about plant availability? There is probably less selection in fall, but good nurseries do have many plants available because fall planting is becoming more popular. The other potential benefit is that there are good sales in the fall. A low price may or may not be a good thing. If the plant is in good condition it is a good time to buy. But in fall you also find trees that have been sitting in the nursery all summer and suffering due to hot weather. This is more of a problem at your local big box nursery. These mistreated trees are not as good a deal.
Fall planting allows trees to grow more roots before they need to make leaves. But do they survive the winter better than spring planted trees? I have not found a good answer to this question, but I suspect a lot of winter damage is dependent on how the tree was treated before it was planted. Did it sit around for months and months in a nursery with not enough water? Has it grown good roots all summer in the pot and is now root bound? How much damage was done to the roots when it was dug up, and when it was planted?
According to Purdue University, some plants are more susceptible to winter injury from fall planting. “Magnolia, dogwood, tuliptree, sweet gum, red maple, birch, hawthorn, poplars, cherries, plum and many of the oaks are among the plants that are best saved for spring planting.” I would not give too much credence to this list, but it certainly makes sense that some types of trees are more susceptible to winter damage.
Deciduous vs Evergreens
Deciduous trees lose their leaves in fall, and once this happens, the requirements for water are vastly reduced. Growing roots still require water, but that is a small amount compared the what leaves use. Fall planting of deciduous trees works better because of this lower water requirement in winter.
Evergreens keep their leaves/needles all winter and even though their metabolism is reduced, they still lose water all winter long. When the ground is frozen, the roots have trouble getting the water they need, and this results in brown/dead needles in spring. For this reason fall planting is more difficult for evergreens, especially broad-leafed evergreens.
The Gardener Effect
The best time for planting is certainly influenced by the gardener. For fall planting to be successful the tree does need adequate water right up to the time when the ground freezes. If you don’t mulch the tree, or if you don’t water in fall, you are probably better off planting in spring when you are more likely to be in the garden. Newly planted trees need regular watering especially during the first 6 months in the ground. Ideally they will continue to be watered regularly for the first year.
Spring or Fall Which is Best?
If you are still with me you are probably wondering if spring is best or if fall is best. Although many references are quite clear about which they recommend, the answer is not as clear as they make it out to be. The question was recently asked on The Garden Professor Facebook group and the answer was a bit surprising.
The Garden Professors are experts in trees and do tree and plant related research. It is a group that can certainly be trusted with their advice. Here is what they had to say (quotes are from reference #2).
Bert Cregg says: “Location makes a difference. Here in the upper Midwest, my rule of thumb is to wait until spring unless there is a compelling reason that you need to fall plant. I do a lot of post postmortems on landscape planting failures and see proportionately more problems with fall planting than spring planting. This doesn’t mean fall planting can’t or doesn’t work; just the odds of success are better in the spring.”
Linda Chalker-Scott says: “As Bert says, location, location, location. The post postmortems I do often stem from spring planting and no irrigation. Fall planting in our climate (Washington State) is best (because of dry summers), and I’d argue it would work anywhere as long as the soil is well mulched to prevent freezing.”
There you have it, the definitive answer.
The key point here is that trees need to have water during their recovery period of which the first 6 months is critical. The west coast has a very dry summer, but a warmer and shorter winter. Fall on the west coast is a long cool period, with a short cold period which is ideal for root growth. Hot summers are not. In the midwest, summers are wetter and less damaging to a spring planted tree. Fall is shorter, and winter is longer and much colder–a difficult time for a newly planted tree.
A key to the success is the mulch Linda mentions. When I add a 5 inch layer of wood chips to an early fall planting, my ground stays moist right up to spring, without watering. My fall planted trees get lots of moisture and most survive quite well. Similar spring planted trees may need watering during a particularly dry summer.
For climates with longer, more severe winters it is best to plant trees in spring. In climates with milder, shorter winters fall planting works well. In either case the trees must have adequate water, and be planted correctly. In case you are wondering, summer planting also works but it is much harder on the tree and is not recommended.
1) Fall is Ideal for Planting Trees: http://www.hort.purdue.edu/ext/falltreeplanting.html
2) Discussion about the best tree planting time: https://www.facebook.com/groups/GardenProfessors/permalink/10153401177806490/
3) Photo Source: USFS Region 5