Tree root collar health is vital for overall tree longevity, and April is an ideal time to inspect it for potential issues.
Winter snows have cleared in April, making the trunk visible, and soft spring soils make early corrections easier. Adding tree root collar inspections to your spring tree inspection checklist helps ensure any trouble spots are addressed before summer stress from drought, wind, and other factors sets in.
Read on to learn more about common root collar problems, including mulch volcanoes, how to check root collar health, and when to call for a professional to intervene.
What Is a Root Collar (and Why It’s Critical)?
The root collar is the transition zone where the trunk becomes the roots. It’s responsible for stability and nutrient transport.
Root collars can decline when there’s soil or mulch too close to the trunk, making them susceptible to suffocation, rot, and other issues that become detrimental to your tree’s health.
3 Common Problems Found in April Root Collar Checks
Here are three problems commonly found during a tree root collar inspection:
- Buried Root Flare – A tree planted too deep into the ground or years of mulch buildup often cause tree root flare problems. Make sure to plant trees at the correct depth to protect the root flare.
- Girdling Roots – Girdling roots are circular roots that strangle the trunk. While all tree species can experience girdling roots, they are more commonly found on maple, ash, and linden trees. The signs of girdling roots are usually invisible until the soil is pulled back. If they aren’t too large, removal requires digging up the soil around the root and then removing it with a tool such as a chisel or saw.
- Mulch Volcanoes – Mulch too close to or touching the trunk, known as mulch volcanoes, encourages insects, disease, and collar rot. Make sure to properly mulch your trees when the time comes.
DIY Root Collar Inspection — What to Look For This April
Knowing how to check root collar health is the first step in identifying issues and determining if professional help is needed.
If your root collar is buried, carefully remove the soil or mulch using hand tools or a small shovel to expose the root flare. Look for signs of girdling roots, such as roots circling or cutting into the trunk, decaying soft bark, or fungal growth and pests. Make sure mulch is less than 4 inches high and not too close to the tree trunk. A tree should not look like a post going into the ground, it should have a gentle flare out.
Tip box: “If you can’t see the first root within 1–2 inches of the soil line, it’s time to investigate.”
Why April Is Ideal for Corrective Action
Spring offers softer soil for easier excavation, and tree recovery is quicker due to the active growing season. Summer heat can stress trees during or after excavation.
April is also ideal to reposition mulch before the summer heat.
If needed, a professional arborist can use tools like air excavation to safely expose collars and assess root problems. Davey’s ISA-certified arborists have the knowledge and expertise needed to inspect, identify, and treat root collars.
CHECK FOR SOIL COMPACTION DURING SPRING
FAQ: Homeowner Questions About Tree Root Collars
A healthy root collar shows a visible flare where the trunk widens into major roots. A tree should not look like a telephone pole coming out of the ground, you should be able to see this flare at or just above the soil surface.
Girdling roots often form a tight circle around the trunk, just below the soil line. If you see roots pressing against the trunk or circling, or if the root flare it seen on one side but not the other, call a certified arborist.
Yes! Pull mulch back at least 3-4 inches from the trunk and keep it 2 to 4 inches deep. Avoid piling mulch directly against the bark.
No. When done professionally with an air spade, exposing the root flare helps the tree breathe and prevents long-term decline.
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