How long do stumps take to decompose?

When it comes to grinding, you’ll have to wait for the stump to decay before building over the spot. Why? Because the underground part of the stump will leave a sinkhole behind as it rots, creating cracks and/or potholes in garage slabs, foundations, driveways and patios.

Exploring the question of how long stumps take to decompose helps us address two other important questions about stumps:

1. Should you remove your stumps, or let them rot?
2. How soon after grinding can I build over where a stump used to be?

When it comes to grinding, you’ll have to wait for the stump to decay before building over the spot. Why? Because the underground part of the stump will leave a sinkhole behind as it rots, creating cracks and/or potholes in garage slabs, foundations, driveways and patios.

You can read more about that in this article, where we discuss the best stump removal strategies for lot clearing.

​WHAT CAN AFFECT THE LENGTH OF TIME FOR A STUMP TO DECAY?

Various sources from across the web offer all kinds of different estimates on the length of time it takes a stump to decay, ranging from 3-10 years. This is, of course, depending on various conditions.

In our experience, a reasonably hardy tree like a Doug fir can take longer than 5 years to decay completely after grinding. Grinding, of course, speeds up the process by completely killing the stump and burying it in the soil.

Yes, a stump is technically still alive after the tree is cut down. It’s living on reserves in the root system. As long as it has reserves, it will try to send up new shoots and grow new foliage to capture sunlight for photosynthesis.

If you don’t take action to finish off a stump, it will struggle for survival as long as it can. There are various methods you can use to kill a stump, such as applying Epsom salt, or covering it to block the sunlight.

How long a stump takes to decay depends on several conditions, including:

• health of the tree/stump
• amount of moisture
• amount of sunlight
• size of the tree
• type of tree

Size and the type of tree are the most significant factors. Certain trees, like cottonwoods and poplars, can send up shoots that grow like weeds. However, these trees are not very resilient to decay. Once they’re truly dead, they’ll rot away much faster than others.

Which species are most resistant to decay?

While we can’t give you exact numbers on how long a stump will take to decay, we can share a useful resource about which trees are most resistant to decay. The USDA Forest Service’s Forest Products Lab categorizes trees in three groups: very resistant, moderately resistant, and not very resistant.

The lists below only include species found in the Puget Sound. If you live elsewhere, you can view the whole document here.

 Very resistant

• Pacific yew
• Black walnut
• Some oaks, including – bur, chestnut, gambel, Oregon white, post and white
• Cedars and cypress (of which the misnomered Western red cedar is a part)
• Black locust

Moderately resistant

• Doug fir
  
• Pine (eastern white, longleaf and slash)
  
• Tamarack
  

Not very resistant

• Cottonwood
  
• Alder
  
• Hemlock
  
• Most pines (presumably the lodgepole and ponderosa)
  
• Red and black oak species
  

 For help identifying your tree or stump, you can refer to our Western Washington Tree Library.

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You can schedule an estimate for your tree or stump removal with Snohomish Tree by filling out one of our estimate forms.