I’ll come right out and say it. Last year was the first time that I ever planted a tree in my own yard. I’ve planted plenty of shrubs over the years, and I’ve planted trees in a few other places, but never one in my own space. It was exciting.
After all the time that I spent picking out the “right” trees for our space, I didn’t want to ruin everything by messing up the placement and establishment of the trees. We went about planting the trees, thinking that we had a good sense of what we were doing. We were careful to try and create conditions that would lead to long-term health and happiness of the new trees. We’d given plenty of thought to their future size and growth and care. We built mulched beds underneath them, with plenty of space. But, in the end, I learned that what we did could have been improved upon. And I know that when it comes to planting trees, there are probably more questions than the clear answers.
A few weeks ago, a colleague and I hosted a live Zoom session for a group of gardeners that we’re providing a season-long gardening program subscription for (it’s called The YARDening Club). We had a friend and colleague of mine (Toso Bozic – www.yardwhispers.ca) come on as the expert speaker. We talked about the when’s and how’s of planting a tree. It was incredibly informative. I decided that I would share some of what I learned (or relearned, in some cases).
Tips for planting a Tree
When is the best time to plant a tree?
The best time to plant a tree depends on what kind of tree that you have and what size it is. Larger, caliper trees (those that are balled and burlap, with a large trunk) are often planted in September or October, before freeze-up. Most people aren’t going to be spading in a tree on their own, so we’ll move on from them for now.
Smaller sized trees, which is what is typically planted by your average person, are planted in spring and summer. Planting in spring means you have a whole season for the plant to grow. The later you go, the shorter time there is for plants to establish a root system and settle into place.
You can start planting trees around the time that you would plant a garden, which is when temperatures have warmed up and the chance of frost is minimal.
Things to understand about the plants that you are buying
Most of the trees and shrubs that you’ll be planting are going to have some of the following characteristics:
- They’ll probably be in a pot of some sort
- The size of the pot or container will vary with the size of the plant. Some might be small, 2-inch pots, and the plant is just a little stick. Others will probably be anywhere between 1 and 10 gallons, or 3 to 28 litres (called #1 to #10). The size of the tree will vary quite a bit.
- They’ll probably tend to be a bit on the tender side, since they’ll have been brought in from another, milder area, or they will be newly emerged and leafed out. Regardless, they’ll have been receiving plenty of tender, loving care, which makes them a bit wimpy when they arrive in your low-care yard.
- Most are actively growing
- Some smaller ones might be a bareroot plant, but most of the time you’ll buy a potted tree.
- Most of them will be a bit root-crowded in the container, which can lead to challenges down the road. Try and avoid trees that have roots coming out of the bottom of the pot, or ones that have quite a bit of the roots circling the pot, as this will be difficult to overcome.
Digging a hole (well, a shallow dish-like hole)
It might seem like a great idea to dig the biggest, deepest hole you can manage before you take a prolonged lemonade break. But you actually want to dig a hole that is wide and shallow. The hole shouldn’t be much deeper than the size of the root ball of the tree that you are planting.
If you are planting a balled or burlap / basket tree, make a hole that is 2 to 3 times wider than the diameter of the root ball and work up the soil around it (to a width of 5 times that width of the root ball).
If you are planting a potted tree, dig a hole that is 3-4 times wider than the width of the root ball of your tree. So, if you are planting a #5 container (5 gallon / 15L volume), it is about 11-12 inches across, meaning you need a hole that is between 36 and 48 inches (1-1.3m or 3-4 feet) wide.
As mentioned, the hole should only be as deep as the depth of the root ball. It should be like a shallow dish, with sloping sides. You don’t want a vertically tight and sealed hole which will constrict lateral (sideways root growth). You want the ground to the sides of the root ball to be easy for the roots to grow into.
Once you’ve got the hole dug, you can determine if you are about the right depth by using a length of 2×4 or a shovel handle across the top of the hole and the pot, to see if you are roughly level. There will be fine-tuning before you are done, but it is easier to have it close at this point.
Once you’ve got the right sized hole/dish, you can improve the soil you removed, working it all up and breaking up the lumps. Put some of it back into the hole, so that you have firm but still loose soil, which is gently sloping towards the middle of the hole. If you have a heavy soil, you might add some organic matter, but not a whole bunch. You don’t need to fertilize the tree at all.
Planting the tree
Carefully remove the root ball and tree from the pot by tapping the pot carefully on the sides. You don’t want to yank out the tree by the trunk, as you might damage the roots. Once the root ball has been liberated, hopefully it won’t be too rootbound (choose wisely before this point).
If the roots are crowded or somewhat rootbound, you can make an X-cut across the bottom of the root ball and then some vertical cuts up the side of the root ball. You aren’t trying to saw through everything, just loosen things up a bit and maybe encourage some new rooting.
Place the tree into the bottom of the hole. Using your handy 2×4 or shovel handle, check that the hole is the correct depth. You want the crown or root collar to be just above the finished grade of the soil. If you are too deep, add some soil underneath until things sit as they should. The root collar is a flared or slightly widened area where the trunk and the roots separate into their respective areas. You don’t want to bury the root collar, otherwise you can get some rotting and problems down the road.
Once you’ve got the depth correct, fill in the soil to make sure that the tree is properly upright and straight. Pack the soil so that there aren’t any air pockets or loose areas. Once things are secure, you can continue to fill in the hole, packing as you go. Fill the hole so that the soil is just below the root collar and the root ball is just covered.
Post-planting efforts
Once the tree is in the ground, you want to make a sort of a lipped area a little way out from where the root ball is. This should be about one foot (30cm) or more out in all directions. This is to give you a way to put on a bunch of water that will gradually soak into the soil. Water the tree well, so that the soil is good a soaked.
Apply a 2–4-inch (5-10cm) layer of bark mulch in a 3-foot (1m) diameter area under the tree. This will conserve moisture and protect the establishing tree. When applying the mulch, don’t let it rest up against the bark of the tree, as this will promote rotting. When applying mulch, always think DONUT, not VOLCANO.
If you are in an exposed area, and the tree might be blown around a lot, you might stake the tree for a year or two (depending on how whippy it is). Be careful not to let the trunk become damaged from whatever you use to tie it (use a piece of old garden hose to blunt the rope or whatever), don’t tie it too tightly, and don’t forget to remove the tie when you are done.
Water occasionally, as required. If it is dry, water every week or two, focusing on deep watering out by the edges of the canopy, which is where the dripline is. The dripline is the area where most of the active roots are.
Some good resources
Toso recommended a short and simple video that can be found on the following link. It uses a small tree, but the principle is the same. The pictures that I have included in this article are adapted and expanded from the information on the page.