Spring and fall are good times of year for tree planting. Unfortunately, many newly planted trees will die within the first few years simply because they were planted incorrectly. Learn the simple steps to properly plant a new tree so you can enjoy its benefits for many years to come.
In this article, we cover:
- how wide and deep to dig a hole in which to plant your tree,
- what to backfill the planting hole with (and what you shouldn’t do),
- whether or not to stake your tree,
- the best thing you can do right after your tree is planted, and
- how to make sure it gets enough water.
How to Dig a Planting Hole for Your Tree
The hole you dig for your new tree is its literal foundation for life. There are two important considerations when you dig your planting hole: width and depth.
Planting Hole Width
Dig a hole that’s two to three times the width of your tree’s rootball. You want to make sure the soil around your new tree’s root ball is:
- Loosened and well-draining – Bare, open soil can become compacted easily, making it hard for water to drain and for tree roots to penetrate. This is especially true if you have clay soil.
- Free of rocks and debris – Remove everything that can block tree roots as they grow.
- Easy to amend, if needed – Use your shovel to mix amendments evenly into the soil so it’s ready for you to backfill (but ONLY if needed – see below for details).
Planting Hole Depth
The depth of your planting hole should be about the depth of your new tree’s rootball, NOT DEEPER than the rootball!
You want the base for your new tree’s rootball to be solid and stable so the tree won’t sink down over time.
If you accidentally dig a hole that’s too deep, just backfill with some soil and tamp it down with your feet until the soil is stable, and the depth is right for your tree’s rootball size.
Planting at the Right Depth
This is the most important part of tree planting. The number one reason for tree decline and death is that people plant trees too deep. Don’t worry, though, because it’s easy to avoid once you learn how.
There’s no magic formula to follow, but you want to plant your new tree so its trunk base (trunk flare) is slightly higher than the soil around it. Look for the spot at the tree base where it widens out and the roots start.
A tree’s trunk flare should always be visible. If you can’t see your tree’s trunk flare, your tree is planted too deep.
PRO TIP: You may need to pull soil away from the rootball to find the trunk flare. Many new trees are planted too deeply in their nursery container or burlapped rootball.
Avoid Planting in Low Spots
If you plant your new tree in a low spot, you risk:
- Water pooling instead of draining away from the tree’s rootball, and
- Soil and mulch washing down and collecting around the trunk flare, eventually covering it up.
All these things can cause fungal growth, attract insect pests, and damage or kill your tree over time.
Backfilling the Planting Hole
After you’ve positioned your new tree in its planting hole, you’ll need to backfill it with the soil you dugout. (This is easier to do with two people: one person holds the tree steady, and the other shovels the soil in around the tree’s rootball.)
Should you amend the backfilled soil?
You may have heard that you should add amendments to your backfilled soil. However, this isn’t usually necessary, although the answer is more complicated than a simple yes or no.
If you regularly add compost and mulch to your garden soil, chances are good you’ve improved its structure and fertility to the point that it can support a new tree’s needs. In this case, you probably won’t need to incorporate amendments into the backfill.
Before you automatically amend your soil, ask yourself:
- Are your other trees and shrubs healthy and growing well? If you don’t regularly give them fertilizers, it’s a sign your soil already has all the nutrients your plants need.
- Are you planting a native tree? Tree species that are native to your area will prefer your soil the way it is.
The only way to know if your soil lacks nutrients and needs amendments is to have it tested. Soil test kits you buy in a hardware store are cheap, but they are not reliable or accurate. You don’t want to over-fertilize!
PRO TIP: In Massachusetts, you can get your soil tested in a in a soil-testing lab for free. You’ll need to follow the directions for submitting a soil sample and wait for results, but you’ll get professional, scientific analysis and instructions for how much to amend your soil.
Avoid Creating Air Pockets When Planting
When you backfill a planting hole, make sure the soil settles evenly around your new tree’s rootball. If you backfill unevenly, you might be creating air pockets.
You want air and water to move freely through your soil, but you don’t want air pockets. These act like barriers in the soil, as tree roots won’t grow in them and water will collect instead of draining.
To prevent this from happening:
- Backfill soil in layers – After you add a layer of soil, water well so the soil settles evenly and air escapes. Repeat until you’ve backfilled all the soil.
- Tamp the soil gently – After backfilling, gently tamp down the soil surface with your foot. Don’t stomp on the soil or you’ll compact it to the point that neither water nor air can penetrate it (a sure way to kill your new tree!).
- Thoroughly water your new tree – Water in your tree, making sure all of the soil is well wetted.
Should You Stake a New Tree?
Not all trees will need staking, but many will benefit from some support for the 6 to 12 months after planting. Whether or not to stake a new tree depends on several factors.
If your tree has a heavy or dense crown and a small rootball, it’s more likely to blow over in strong winds until its root system is established. In this case, tree stakes are a good idea.
Young trees get tall and skinny when they’re grown closely packed in nursery containers and tied to nursery stakes. When you take off this stake (and yes, you should always remove the nursery stake when planting a new tree!), the tree may flop over. Staking will keep a skinny tree upright until its trunk grows larger and stronger.
In contrast, small, stocky, or spreading trees are less likely to blow over and generally won’t need staking.
If you’ve planted a small tree in a sheltered location, you probably won’t need stakes. Windy spots, however, usually mean staking will be needed.
Type of Rootball
Balled and burlapped trees have larger root systems than trees grown in nursery containers, and often don’t need staking because their rootball holds them steady.
How to Stake a New Tree
If you do stake your trees, do it right. Typical staking uses:
- Two or three large, strong stakes driven into the soil outside the tree’s rootball (not into the rootball itself), and
- Soft, flexible ties fastened securely to the stakes (they can even be nailed or screwed into the stakes) and loosely tied around the tree’s trunk
- Three anchors driven into the soil around a tree, and
- Nylon webbing tied to the stakes and attached to flexible ties around the tree’s trunk.
Position the stakes so that they don’t touch branches (they’ll rub off bark as branches move against them). And never tie a new tree directly to a stake.
Attach the flexible ties at the lowest possible height to keep your tree upright.
The goal is to prevent the tree from falling over, not to prevent it from moving. You want your tree to move in the wind – this helps it grow stronger. You just don’t want it to bend so much that the trunk snaps.
- Don’t use rope, twine, or metal wire, or cable to tie your tree. These will rub off bark or cut into the tree’s trunk as it moves.
- Check your staked tree after six months and remove stakes as soon as your tree can stay up on its own. Staking a tree for too long will stunt its natural growth.
Mulching a New Tree
Always add a layer of organic mulch around your newly planted tree. The benefits of mulch include:
- Slowing water evaporation from the soil
- Smothering weeds that compete for water and nutrients
- Regulating soil temperature extremes
A rule of thumb is to add a circle of mulch two to three feet in diameter around the tree’s trunk. Not only does this give you the many benefits of mulch, but it also gives you a clear “no-mow” or “no plant” zone over its roots.
Spread a three- to four-inch layer of mulch and regularly replenish it.
Avoid this Mulching Mistake!
Never make a mulch volcano! This is when you pile mulch up around the base of your tree’s trunk. We’ve all seen trees mulched this way but that doesn’t mean it’s the right way to do it. In fact, mulch volcanoes are one of the leading causes of tree death.
Remember that you always want to see your tree’s trunk flare (the area at the tree base that widens out just before the roots start).
Taper down the mulch depth as you get near the trunk and don’t place any right against the trunk. Think of creating a mulch “donut” around the tree, rather than a mulch volcano.
Watering Your New Tree
After you plant your new tree, it will need regular watering. A tree’s rootball at planting is small, and it’s the only resource for a tree to take up water.
For the first few weeks, you should water your tree every day. Let the water soak down into the soil so the entire rootball is moist.
After that, water weekly throughout the first growing season.
Always water “low and slow” so that water soaks down into the soil and encourages deep roots.
Once the weather cools in fall and the rains are regular, you can generally stop watering until spring. However, if we get a warm spell in winter and the ground is clear of snow, your new tree will benefit from winter watering whenever possible.
You’ve planted a tree, done it right, and now you can sit back and watch it grow. You’ll know you’ve done something good for yourself, songbirds, bees, butterflies, and the planet!
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