How to Rot a Tree Stump Fast

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Removing tree stumps, or getting tree stumps to rot faster than they would naturally, is actually quite simple.  By learning how to make a stump rot faster, you can remove tree stumps naturally without resorting to calling in an expensive tree service.

Living on a woodland homestead and cutting all our wood year after year means we have a lot of tree stumps.  Now with the emerald ash borer, pine bark beetles, and all manner of other pests killing off whole tree species, we find ourselves struggling to keep up with all the standing dead wood. 

This past year, we lost several acres of ash trees to borers and decided to make the best of it by turning the land into pasture.

Generally, converting woodland to pasture requires decades of patience while the stumps rot naturally or hiring a bulldozer or commercial stump grinder to clear the land faster.  Both of those mechanical techniques can be incredibly damaging to land and soil, not to mention expensive. 

Encouraging stumps to rot naturally in place can save you a lot of money, not to mention prevent erosion and other damage to your land in the process.

Whether you have just a single stump to rot on in your front yard, or hundreds of stumps to rot in your back forty, the process is the same.

How Long Does it Take Tree Stumps to Rot?

Tree stumps will rot naturally over time, but in most cases, they take a very long time to rot away fully. 

Even soft wood from pine trees can take 15 to 20 years to rot away entirely, and more rot-resistant hardwoods might still be in place 50 or more years after the tree itself is gone.  How do you make stumps rot faster?

The trick is using a bit of biology and encouraging the natural biological processes that break down wood in the first place.  With a bit of encouragement, you can fully rot a stump in as little as 6 weeks in ideal conditions. 

Even without ideal conditions, stumps can be fully rotted in as little as 8 to 12 months with this technique (instead of decades).

How to Rot Tree Stumps Fast

If you want to make a stump rot faster, the main trick is increasing the surface area so it’s more exposed to the elements while at the same time feeding the bacteria and fungi that will decompose the stump.  In a nutshell, that means drilling holes into the stump and then adding nutrients. 

The basic steps to rot a tree stump are:

1. Cut the Tree Stump Off as low as you can ~ The less material there is to rot, the faster it’ll break down.  Try to flush the stump off as close to ground level as possible.
2. Drill holes into the remaining stump ~ By making holes down into the tree stump, you’re encouraging water and nutrients to be trapped in the wood, which will make it rot faster.
3. Add Nutrients ~ One of the reasons trees don’t rot quickly is they’re almost all carbon.  To compost properly, microbes need carbon, nitrogen, and other trace nutrients. 
4. Mulch the Stump ~ This helps hold in moisture and encourages the stump to break down faster.  Any natural mulch will work, from bark mulch to just raked leaf mulch.

Cutting The Stump Off Low to the Ground

The first step is pretty self-explanatory.  Get the stump as low as you possibly can.  If it’s possible to run a chainsaw (or hand saw) parallel to the ground and flush the stump off at ground level, that’s perfect.  Some stumps are tricky, and they’re either oddly shaped or just too large to cut reasonably, but do the best you can. 

The less wood there is to rot, the faster the stump will disappear.

Drilling Holes in Stumps

Next, drill holes in the stump. 

They should go down vertically into the stump so that they create little pockets to trap rain, moisture, and nutrients.  Water rots wood quite effectively, and making sure the stump stays consistently moist is the first step.

If you just have a single stump to rot, choose the biggest drill bit in your toolbox and make as many holes as you can with a small electric drill.  Ideally, you’d want holes about 1/2 inch wide and a couple of inches deep.  A cordless or corded drill with a sharp bit can drill a single hole in about 3 to 5 seconds, and you want to aim for as many holes as you have the patience to make.

In our case, we’re trying to rot around 40 stumps, so we’re using something a bit more heavy-duty.  It’d take hours to drill holes in that many stumps with a cordless drill, but it takes about 5 minutes with an angle grinder and drilling attachment.

Generally, angle grinders spin at too high a speed for drilling, and you cannot use regular drill bits in them (they’ll break).  Commercial mushroom farms drill a lot of holes in wood to put in mushroom spawn plugs each season, and a hand drill is way too inefficient.  They’ve developed strong, sharp drill bits and an attachment that will turn an angle grinder into a hole drilling machine.

If you’re trying to rot a lot of stumps at once, I’d highly recommend investing in an angle grinder and a drilling adaptor.

We’re using the following:

• Battery Powered Angle Grinder ~ It’s super efficient, and you can drill holes in about 40 stumps (10 to 18 inches each) on a single battery charge with the Makita model.  It also has a “stay on” mode, which allows you to drill holes as fast as you can move.  (Be careful though, it will drill through you faster than a stump.)
• Angle Grinder Drill Attachment ~ This allows you to put a specialized drill bit into your angle grinder.
• Drill Bits for Angle Grinder ~ These are specifically designed to drill quickly into the wood and take the high torque of an angle grinder.  Do not attempt to use regular drill bits in an angle grinder.  They come in 8.5mm and 12mm sizes.  Both will work for rotting stumps, but the bigger one will be more effective.  

With this setup, I can literally drill 3 to 5 holes in a second.  The bit cuts through wood stumps like a hot knife through butter, and it takes no more than 5 seconds to drill a few dozen holes in a single stump.  (A regular drill would take about 10 to 20 times as long, and is much harder on your wrists as you work.)

An angle grinder has dozens of other uses when you’re not drilling stumps, so it’s a handy tool to have around.  The drilling setup is relatively inexpensive, so worth it even if you’re only using it for stumps.  In our case, we use the same setup when we’re growing shiitake mushrooms and other mushrooms on logs, so it comes in handy often.

Encouraging Stumps to Rot

At this point, the holes will already encourage the stump to rot, and cut the whole time to rot in half.  A stump that would have taken a decade to rot will be gone in about 5 years just because the holes trap rainwater.

If you really want to get a stump to rot, you’ll have to feed the bacteria and fungi in the soil, or more specifically, balance the nutrients in the stump to allow the bacteria to efficiently process the wood.

Wood is almost entirely carbon, and if you know anything about backyard composting, you know that it’s important to balance the ratio of carbon to nitrogen to encourage materials to break down. 

The ideal ratio of carbon to nitrogen in compost is around 30 to 1.  That’s 30 parts carbon for every 1 part nitrogen.  Wood is naturally around 500 to 1, since it’s almost entirely carbon. 

The microbes need a lot more nitrogen to break down a stump.

What to Pour On a Stump to Encourage Rot

There are a lot of ways to add nitrogen to a stump to encourage rot.

The most effective method is to add pure potassium nitrite pellets, which are just pelletized nitrogen fertilizers.  You can buy this inexpensively online, but it’s usually not available in local stores.  It’s too concentrated to be used on plants as it is, so it’s not sold that way at your local garden store.

Potassium nitrite is actually sold as “stump remover pellets,” and commercial sump remover solutions are almost entirely potassium nitrate.  Spectricide stump remover, for example, is liquid potassium nitrate along with a bunch of other chemicals that help kill the tree down to the tip of the roots at the same time.

Lab-grade potassium nitrate is much less expensive if you have a lot of stumps to remove, and it’s much more natural than a prepared blend that includes other potential toxins.

Be aware that while potassium nitrate is a natural source of fertilizer, it’s not exactly something you want to bathe in or allow your pets to eat.  If you have pets around, do not let them eat the powder.

If you can’t keep pets away from the stump, I’d suggest going with a bag of “yeast nutrient,” which is a food-grade nitrogen that’s used in winemaking.  It’s meant to feed the yeast in a fermentation process, and it’s completely food safe.  Be aware that “yeast nutrient” is not the same as nutritional yeast, and it can only be purchased online or at specialty winemaking or homebrewing stores.   

Beyond that, you can use other sources of nitrogen like regular pelleted fertilizer or even a few scoops of miracle grow.  Lawn and garden stores also sometimes sell bags of “compost booster,” which will also work.

Other than fertilizer, you can also use other things you have on hand, like natural buttermilk.  In a pinch, urine does the job too.  Yes, you can dissolve a stump by drilling holes into it and peeing on it regularly.  Put your boys to work, and it’ll be gone in no time. (Make sure you drill holes though, that’s what traps the nutrients against the wood.)

Things You Can Use to Rot a Stump

So, in summary, once you’ve drilled the holes, you can use any of the following to rot the stump:

• Potassium Nitrate Pellets ~ The most effective method, but not pet safe.
• Yeast Nutrient ~ Actually just food-grade urea, so a source of food-safe nitrogen that you can use around pets/kids/etc.
• Miracle Grow (Or other high nitrogen fertilizer) ~ Works well, more available locally, but not as concentrated as potassium nitrate.
• Cultured Buttermilk ~ Natural cultured buttermilk is also a good source of nitrogen, and it contains probiotics that will help digest the stump.  It’s much slower than other nitrogen sources, and you’ll need to dump a bit more buttermilk on the stump every week or two in order to encourage breakdown.
• Urine ~ Lacking other things, you can just pee on the stump regularly to add nitrogen.  This is the least effective method, as urine doesn’t have nearly as much nitrogen as actual fertilizer.  Still, if you only have a single stump to rot and it’s in a private spot, you can just drill holes and encourage the men in your house to go to work on it every day.

Things You Shouldn’t Use to Rot a Stump

When rotting a stump, you’re trying to encourage biological activity.  DO NOT use things like bleach.

While bleach will kill the tree quickly, it also kills the microbes in the wood and sterilizes the environment.  That’s exactly the opposite of what we’re going for here.

Beyond that, things like Epsom salt will encourage rot to some extent, as they do add nutrients.  Epsom salt is a magnesium salt, and many microbes do require magnesium, at least in low levels.  It’s not the main limiting nutrient though, and it won’t be nearly as effective as adding nitrogen.

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