Tree and roots depicting how to grow trees in compacted soil

5 Ways to Help Trees Grow in Compacted Soil

Tree and roots depicting how to grow trees in compacted soil

Are you having trouble growing your trees in compacted soil?

Facing compacted soil as a homeowner can be frustrating when planting trees.

How to help trees grow in compacted soil

Soil compaction is one of the leading difficulties of trees growing in suburban settings. The simple application of pressure from vehicles, foot traffic, and even raindrops causes soil to become compacted. The greater the pressure is, the greater the soil compaction.

When soil is compacted, it reduces the amount of water, nutrients, and air in the soil, making it difficult for the tree’s roots to grow.

According to the Department of Horticulture at Cornell University,

Soil compaction is the single most difficult and harmful environmental or abiotic condition that a tree or shrub can experience.

Arborists estimate that 40% of all commercial and residential properties suffer from soil compaction near trees. The Artistic Arborist Inc., a full-service tree and plant health management firm stated:

“Roots growing in compacted soil must exert more energy, robbing above-ground growth. Compaction diminishes water infiltration and drainage capabilities creating damp soils that foster anaerobic disease organisms, soil erosion, and further compaction.”

Urban Soil Compaction Problem

Trees in harsh environments in NYC

Trees in harsh environments along sidewalk in NYC

Soil compaction is a big problem for urban trees and plants. But what is it about the makeup of soil that causes this problem?

The ground you and I walk over is only half of what you see and feel; that is, mineral particles (like sand), silt, clay, and organic matter.

The other half of soil is or should be pore space. In other words, empty air. It is the room for air and water movement that is essential for soil to do its job.

Pore space is as crucial to the life of your tree as the nutrients in the organic matter.

Why?

It is important because living plants need air and water around their root systems as well as above ground. They need beneficial microorganisms and worms to be able to thrive there. The ground, it turns out, is a living thing.

Pressure Causes Compaction

The fact that our soil has pore space means it’s collapsable under heavy weight.

The soil particles become pushed tightly together, so there is nowhere for air and water to move or microorganisms to live.

The soil may stay wet for longer than the plants need, causing root rot. In addition it is more difficult for trees to become established because their energy must be spent sending out their roots.

Beings the size of humans and animals don’t do much harm to the soil. However, lots of foot traffic, lawnmowers, heavy rains, big machines, and paving materials all do their part to make tree growth difficult.

All of these things are present in abundance in urban environments. Compaction is more likely when soils are made up of heavy clay or loam, but even sandy soil doesn’t stand a chance in the city.

Is Your Soil Compacted?

Compacted soil is likely if you live in an environment with a lot of these things.

However, there are easy ways to tell. If you pull up a section of soil and it looks grayish and dull and feels very dry, it’s probably suffering from compaction.

Likewise, if it’s hard to push a spade or a stick into the soil, you probably have a problem.

Are Your Trees Suffering?

Another way to tell if your soil is compacted is by the health of your trees.

In other words, if your trees seem to be doing poorly and you don’t know why it could be soil compaction.

Compacted soil stresses trees, so they are more susceptible to pests and environmental stresses like droughts.

If you see poor growth and fewer or smaller leaves, or even branch die-back, it could be the soil.

If you give your trees some extra care and they still don’t respond, you may have to fix your soil compaction problem.

Here are five ways to help your tree grow in compacted soil:

  1. Select an Optimal Planting Area
    Develop a planting area that is large enough to contain the root structure. Keep in mind that you want your planting pit to be three times the size of the rootball.
  2. Look For Drainage Problems
    After you have dug out the planting pit, fill the hole with water. It is crucial to make sure that the water drains from the hole. Standing water indicates a poor planting area. At that point, you may need to select a different site or take additional steps to ready the site for your tree.
  3. Properly Cultivate the Soil
    By turning or cultivating your soil below the rootball, you will provide your tree with the necessary aeration and drainage that it needs in compacted soil. If you’re trying to help an established tree that is suffering, mix good compost into the top 10 inches of soil around your tree. You can further cultivate the soil by adding earthworms. Worms help to aerate the soil by eating their way through compacted soil and restoring some of those healthy spaces.
  4. Choose Your Mulch Wisely
    Mulch is important. Use high-quality mulch without a weed protection mat. Weed protection mats prevent the natural decomposing of the mulch from reaching the root zone, which is the opposite of what you want. Good mulch acts as a very slow-release fertilizer for your tree. We recommend double shredded hardwood for your trees. Make sure to spread the mulch in a ring around the tree, but avoid stifling your tree with mulch. The addition of mulch will keep your tree base free of lawnmower compaction.
  5. Install Root Aeration Tubes
    Rootwell Pro-318 Deep Root Watering System

    Rootwell Pro-318 Deep Root Watering System


    Placing Rootwell Pro-318 deep root aeration tubes around your trees in compacted soil will strengthen your tree’s ability to live. The Rootwell Pro-318 system provides nutrients, water, and oxygen to the root zone allowing roots the best chance of survival.

Takeaway

Growing trees in compacted soil may be a challenge, but not an impossible one. With the right tools and knowledge, your trees will flourish and reach their full growth potential.

 

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