7 Tree Planting Mistakes to Avoid in Autumn

Short on Time? Read Our Summary on Common Tree Planting Mistakes in Autumn.

The most common tree planting mistakes include planting too deeply, digging a hole that is too narrow, leaving roots tightly bound, adding too much compost, failing to water thoroughly, staking incorrectly and piling mulch against the trunk.

When planting a tree in autumn, keep the root flare at ground level, give the roots plenty of room to spread, water thoroughly after planting and apply mulch in a flat layer away from the trunk.

Autumn is an excellent time to plant many trees in the UK because cooler weather reduces water stress while the soil can remain warm enough for roots to begin establishing before winter.

Autumn Is One Of The Best Times Of Year To Plant a Tree.

The intense heat of summer has passed, rainfall usually becomes more frequent and the soil can remain relatively warm even as temperatures above ground begin to fall. These conditions give newly planted trees an opportunity to start establishing their roots before winter.

Getting your tree into the ground is only the beginning, though. How you plant it can make a big difference to how successfully it establishes.

From digging too deep to adding too much compost, here are seven common tree planting mistakes to avoid this autumn.

Read our full guide on planting trees in autumn.

1. Planting Your Tree Too Deep

One of the easiest mistakes to make is planting a new tree too deeply.

It can be tempting to assume that placing the roots deeper into the ground will make the tree more secure. In reality, the base of the trunk should not be buried beneath the surrounding soil.

Look for the root flare, where the base of the trunk begins to widen and meet the roots. This should remain around ground level rather than disappearing beneath several centimetres of soil.

If a tree is planted too deeply, the lower trunk can remain damp and the roots may receive less oxygen than they need.

Before filling your planting hole, place the tree inside and check its height against the surrounding ground. It is much easier to adjust the depth at this stage than after everything has been filled in.

2. Digging the Planting Hole Too Narrow

The planting hole doesn’t need to be extremely deep, but giving the roots plenty of space around them can help them establish.

A narrow hole surrounded by hard, compacted soil can make it more difficult for new roots to spread out into the surrounding ground.

Instead, dig a hole considerably wider than the tree’s existing root system and loosen the soil around the sides.

The exact size will depend on the tree and its rootball, but think wide rather than excessively deep.

The bottom of the hole should also be firm enough to support the tree at the correct height. Digging deeply and then filling the bottom with loose soil can sometimes result in the tree settling lower after planting.

3. Leaving the Roots Tightly Bound

If you’re planting a container-grown tree, take a moment to look at the roots when you remove the pot.

Trees that have spent some time growing in a container can develop congested roots around the outside of the rootball.

If you find roots tightly circling the outside, gently tease out suitable roots before planting so they are encouraged to grow away from the rootball and into the surrounding soil.

You don’t need to remove all of the compost or completely dismantle a healthy rootball.

The aim is simply to make sure the roots have the opportunity to spread outwards as the tree establishes.

4. Adding Too Much Compost to the Planting Hole

This one can seem counterintuitive.

If compost is good for plants, surely filling the planting hole with rich compost will give a new tree an even better start?

Not necessarily.

Creating a small pocket of very rich, soft growing material around the rootball can discourage roots from moving into the surrounding garden soil.

Instead, your tree ultimately needs to establish itself in the soil where it will spend the rest of its life.

In most situations, the soil removed when digging the hole can be used when backfilling around the tree. Depending on your soil conditions, suitable organic matter may be incorporated where appropriate, but avoid simply replacing the planting soil with a hole full of compost.

Improving the wider soil over time is usually much more useful than creating a small compost-filled planting pocket.

5. Not Watering Thoroughly After Planting

Autumn may bring cooler and wetter weather, but that doesn’t mean a newly planted tree won’t need watering.

Once you’ve backfilled the planting hole, give the tree a thorough watering.

This helps moisture reach the root zone and settles soil around the roots.

Continue checking the soil during the weeks after planting rather than relying entirely on rainfall. Dry and windy periods can still occur during autumn, and newly planted trees have a much smaller established root system than mature trees.

When watering is needed, a good soak around the root zone is generally more useful than frequently wetting only the surface.

As temperatures fall and the tree becomes dormant, its water requirements will reduce, but don’t assume that autumn rain will always do all the work for you.

6. Staking Your Tree Incorrectly

Not every newly planted tree will require exactly the same support, but where staking is necessary, the goal is to stabilise the roots while the tree establishes.

A tree shouldn’t necessarily be held completely rigid from top to bottom.

Some natural movement of the stem can be beneficial, while the stake and tie prevent excessive movement around the root system.

Make sure tree ties aren’t cutting into the bark and check them periodically as the trunk grows.

Stakes should also not simply be forgotten about. Once the tree has established sufficiently and no longer needs the additional support, they can be removed.

7. Piling Mulch Against the Trunk

Adding organic mulch after planting can be extremely useful.

A layer of bark, woodchip or another suitable organic mulch can help the soil retain moisture, suppress competing weeds and gradually add organic matter as it breaks down.

The mistake is piling it directly against the trunk.

Avoid creating a mound or ‘mulch volcano’ around the base of the tree.

Instead, spread the mulch in a broad, relatively flat layer across the surrounding root zone and leave a clear space immediately around the trunk.

The root flare should remain visible rather than being buried beneath mulch.

Think doughnut, not volcano.

A Quick Autumn Tree Planting Checklist

Before you finish planting your new tree, check that:

• The root flare is around the same level as the surrounding ground.
  
• The planting hole gives the roots plenty of room to spread.
  
• Any tightly circling container roots have been carefully loosened where appropriate.
  
• You haven’t filled the planting hole with excessive amounts of compost.
  
• The soil has been thoroughly watered after planting.
  
• Any stake and tree tie are fitted correctly and aren’t rubbing against the trunk.
  
• Mulch is spread across the root zone rather than piled against the bark.

Give Your New Tree the Best Possible Start

Planting a tree is an investment that can transform a garden for decades to come, so taking a little extra time at the planting stage is worthwhile.

Autumn provides excellent conditions for getting many trees established, and you don’t need to make the process complicated.

Plant at the correct depth, give the roots room to grow, water thoroughly and keep an eye on your new tree while it settles into its new home.

Then, as temperatures begin to rise again in spring, it will be ready for the next stage of growth.

Happy gardening!