With the days getting shorter and cooler temperatures on the horizon, it’s time to gear up for planting new trees in your landscape. Let’s go over some of the basics so you can avoid common planting mistakes, increase your new tree’s viability, and ensure that your new tree is something you can enjoy well into the future.
When To Plant
For most of western Oregon the tree planting season begins in October or November and extends into the spring around April. If you’re in an area with colder winter temps, you’ll want to hold off on planting when the ground is frozen—Transplanted trees don’t like cold feet and it’s no fun to dig in icy soil!
We wait until fall to plant for a few reasons:
- Less transplanting shock – If you can, wait until deciduous trees have lost their leaves for the season. Dormant trees use less nutrients to stay alive and will fare better while they adjust to their new home
- Less need to water – You’ll still need to water your new tree, but the winter rains of the PNW can do some of the work for you
- Less heat stress on roots – Going from cool soil to the warm summer sun can have adverse effects on roots, so it’s best to wait for days around 70 degrees or below
Right Tree, Right Place
There’s no such thing as a bad tree. Just a good tree in the wrong place! By carefully selecting your new tree you can avoid future problems like broken or lifted sidewalks, an overcrowded landscape, clearance issues with buildings/sidewalks/wires, excessive debris clean up, and more.
Some things to think about are:
- Size – Even though your tree is small when you get it from the nursery it’s not going to stay like that forever. Be sure that you have enough space when planting a big shade tree or a tall growing conifer. Don’t plant trees that will get large too close together. It may look like there’s too much space at first, but they’ll fill in over time. While there are species of ornamental trees that will stay moderately sized when mature, avoid planting them too close to houses or other structures
- Functionality – Whether you’re planting your tree for shade, as a windbreak, or to be the centerpiece in your landscape, think about the utility that the tree will offer as it grows and matures
- Long-term needs – Some trees are great at first but become challenging as they grow. If you don’t want to have to water a lot, plant a drought tolerance species. If you don’t want to worry about your sidewalk, plant a tree with less aggressive roots. If your soil has a challenging composition, plant something more resilient and less nutrient intensive. If you don’t like cleaning up a lot of debris, plant a tree with smaller flowers/fruit or a conifer that doesn’t “shed” as much
- Aesthetics – Flowers, fall color, bark texture, and branch structure are some of the main things we find people considering when choosing a tree. With myriad cultivars available these days a little bit of research can help you find a tree with the right look for you and your landscape. (Just don’t forget the other considerations above!)
Most municipalities have a list of species that are to be planted as street trees in parking strips. These guidelines are developed based on the width of the parking strip, the growth habit (morphology) of the tree, and presence or absence of above ground power lines. It’s important to follow the guidelines set by your city along with consulting your arborist or local nursery.
Proper Planting Tips
There’s a lot that goes into establishing a new tree. Here are some of the key things to pay attention to:
- Find the root flare – The root flare is the part at the base of the trunk where it rapidly tapers out into root growth. Sometimes this can become buried at nurseries. Gently dig down near the trunk until you find the flare and remove any excess soil to that level. Trees that are buried too deep can experience root rot which can lead to the decline or death of the tree over time
- Check for girdling roots – When stuck in a pot or burlap for a long time roots can start to circle around the edge of their planting container. Gently cut the circling, or girdling, roots. This will encourage them to move into the soil around the planting hole leading to a more solid base and help them avoid choking each other and the trunk of the tree
- Check you planting depth – Measure from the base of the root ball to the root flare to find your planting depth. Tamp down any loose soil that remains in the bottom of the hole to avoid settling
- Dig wider than the root ball – You want the width of your hole to be about 1.5 times the size of the root ball you’re planting. This will ensure that your tree has loose soil to move into as its roots grow during the first couple of seasons
- Mulch & fertilize – Apply a 2-4” thick layer of mulch out to the drip line of the tree. The drip line is the invisible vertical from the tips of the branches to the ground. If your tree has a fastigiate (upright) growth habit, extend the mulch out a little further. Mulch will help the soil retain water and stay cooler in the summer, suppress weeds, and avoid competition with turf for water and nutrients. Fertilizing will help jump start your new tree. Your local garden store will have a custom blend fertilizer that’s best for new trees. General Tree Service also offers a proprietary soil enhancement that includes fertilizer, humic acid, beneficial bacteria, and a wetting agent. One of our arborists would be happy to tell you more if you’re curious how our soil enhancement is different from over-the-counter fertilizer
- To stake or not to stake – Most new trees don’t need to be staked. If your tree is going to be exposed to a lot of winds, has a particularly tall skinny trunk, or is top heavy you might consider staking for the first 6-12 months until the root ball is fully established. It’s important not to leave your tree staked for longer than necessary. The natural swaying of the trunk will help it build strength
- Watering – After everything else is done give your new tree a good deep soaking. Water it every couple of weeks throughout the winter if rain isn’t keeping the area moist. Deep soaking throughout the root zone is recommended every couple of weeks during the tree’s first couple of summers in the ground
There isn’t much to do once your tree is fully established. Continued watering every couple of weeks during drought months and fresh mulch/fertilizer every couple years will help keep your tree happy. Lastly regular pruning by an experienced arborist will improve your tree’s structure, reduce the hazards of dead branches, and make it more resilient to adverse weather events. This can be done as often as every year for ornamental trees or up to every 5-7 years for large shade trees.
For more information or advice on planting your new tree, reach out to General Tree Service at 503-656-2656.