Is Sawdust Good For Mulch in the Garden

For many reasons, Sawdust is good for mulch in the garden, from mulching your acidic soil-loving plants to improving your soil in general.

Sawdust can sometimes get a bad rap for ” stealing nitrogen” although that’s been largely debunked.

With all of the upsides of sawdust, you’ll soon be adding it to your line up of garden hacks.

Sawdust as a Garden Mulch

I’m always on the lookout for the cheapest and easiest ways to improve the health and productivity of my garden.

A method that’s gaining popularity is the use of sawdust as garden mulch.

Sawdust, a byproduct of wood processing, has several advantages that make it a great choice for any gardener.

Weed Suppression

When used as a garden mulch, sawdust can be a great barrier against weed growth.

If you apply a thick enough layer, usually 2-4 inches, you prevent sunlight from reaching weed seeds, inhibiting germination.

Sawdust can also smother existing weeds to keep them from competing with your plants for water and nutrients.

Unlike some organic mulches, you never have to worry about weed seeds in sawdust.

Water Retention

One of the biggest advantages of using sawdust as garden mulch is it’s ability to conserve water.

By acting as a protective layer over garden soil, sawdust prevents direct sunlight exposure. This reduces evaporation keeping soil moisture at a healthy level.

Steer clear of black walnut sawdust as it can actually harm your plants.

Does Sawdust Take Away Nitrogen in the Soil?

Yes as sawdust is primarily carbon-based, it will take nitrogen from the soil as it decomposes. This is only a problem if you’re removing the sawdust and not allowing it to add itself to your soil.

When you allow the sawdust to break down fully it will add much more to your soil than it takes away.

This is supported by a study done by International Society for Horticultural Science. In this study, blueberry bushes were mulched with varying depths of sawdust.

The result was that the bushes that incorporated sawdust continually produced a higher yield with a firmer berry no matter the ending nitrogen level.

Additionally, the yield was unaffected when the bushes were fertilized with additional nitrogen. You can read the whole study here.

If you’re still worried about nitrogen loss, add extra nitrogen in. It can be as simple as adding some coffee grounds. I toss mine into my compost heap daily and rarely think twice about nitrogen or soil ph.

Sawdust Mulch for Blueberry Bushes and Other Acid-Loving Plants

If you add sawdust as a mulch to blueberry bushes and other acid-loving plants it can keep the acidity of the soil higher.

Avoiding working the sawdust into the soil directly will allow it to break down and add a better form of organic matter to the soil.

Sawdust, like most forms of mulch, will keep the soil cool and moist. This gives you the freedom to plant your acid-loving plants in more full sun. These plants love sun, however, can’t thrive if they dry out.

Plants That Benefit From Sawdust Mulch

• Blueberries
• Strawberries
• Blackberries
• Evergreens
• Conifers
• Rhododendrons
• Azaleas
• Holly
• Tomatoes

Improving Clay Soil

Sawdust is a great way to improve clay soil. Clay soil is pretty dense and heavy. It’s no fun to dig into and it is difficult to till.

The solution here is to amend your soil. There are several viable options, however, you will have trouble finding a less difficult and cost-effective option compared to sawdust.

Adding sawdust to clay soil will improve water drainage in a few different ways. The first is that it lightens and loosens the soil and breaks up soil that may have compacted or clumped.

The best time to add sawdust to clay soil is when it’s wet. The soil is much easier to work with and it will allow you to add your amendment more evenly.

How Long Does it Take for Sawdust to Decompose?

Under the right conditions, sawdust can decompose within four to six months. This is a perfect timeframe for the application of mulch year one, and tilling into soil year two.

If using wood shavings or wood chips the timeline is a little longer 18-24 months.

One good option is to incorporate sawdust into your compost pile. This not only offers a good brown source for your pile, a 6 month decomposition won’t slow your composting process like larger sources of wood might.

Is Sawdust Cheap and Where to Get It?

You can typically find sawdust at a cheaper price by the cubic foot than topsoil. You should be able to source it for free or nearly so from a lumber mill or cabinetry manufacturer.

If you look online, you’ll have better luck searching for wood or pine shavings instead of saw dust. A benefit of buying instead of sourcing from a mill is that you’ll have a better idea of what’s in the wood that was used.

Sawdust can be used for walkways between garden beds.

For several reasons, sawdust can be an excellent option for mulching between garden beds.
If you layer your sawdust mulch 2-4 inches it will begin to suppress the grass and weeds that grow under it.

As it starts to break down and compact, you can till it into your soil adding to your overall soil health. This is especially beneficial if you have clay soil.

Sawdust can be an excellent mulch for new grass seed.

If you’re adding grass seed to your lawn in any application, sawdust can be a great cover mulch to help ensure healthy germination. Click here to learn all about the advantages of mulching fresh grass seed.

If you’re ready to find out more ways to put mulch to work in your garden, Discover 11 Handy Uses For Mulch in The Garden next.