Regardless of what type of garden you keep—it would likely be much better if you applied some mulch to the soil. And today, there are lots of suitable mulch materials, including wood chips, straw, and sawdust. But how safe is using sawdust as mulch in a vegetable garden?
You can use sawdust as mulch in a vegetable garden. This mulch prevents weeds from sprouting and helps the soil to retain vital moisture and nutrients your vegetable plants need. And because sawdust is acidic, it’s also highly beneficial to acid-loving vegetables like broccoli and lettuce.
Read on to learn more about using sawdust as mulch in a vegetable garden, including its benefits in greater detail and how long it takes for the substance to decompose. I’ll also discuss the potential dangers of sawdust mulching and how to solve them. Let’s get started.
Is Sawdust Good Mulch?
Agriculture is an important activity that humans have practiced for several millennia. However, our vital food crops are susceptible to disease, pests, and erosion. To solve this problem, many farmers turned to a crucial practice—mulching.
While the most common mulches are wood chips, straw, and crushed leaves, sawdust is a highly beneficial yet surprisingly unpopular alternative.
Benefits of Using Sawdust As Mulch
It’s relatively inexpensive and can aid plant growth if applied correctly. The benefits are so extensive that it’s worth an entire section in this article. Of course, you’ll only get the full benefits of using sawdust as mulch if you apply it correctly.
Let’s discuss some more to learn how they benefit your vegetable garden.
It Eliminates Weed Growth
Weed growth is a problem that has plagued farmers and gardeners for a long time. Weeds often compete with plants—using precious resources like water, nutrients, space, and even sunlight. They typically grow much faster than crops, outcompeting your vegetables and flowers.
I recommend covering your plant beds with sawdust mulch to prevent weeds from growing. The mulch works by preventing weed seeds from accessing enough sunlight to grow.
However, your mulch needs to be about 2 to 3 inches (5 to 7.6 centimeters) thick to get this result. Even the most stubborn weed seeds will not be able to push through the soil when the sawdust mulch is this thick.
Undoubtedly, some weeds are too stubborn to be stopped by any mulch. If you notice this, I recommend manually pulling out the weeds or using a hoe to remove them from the soil.
Sawdust Mulch Retains Moisture
For any plant to grow, it needs a good amount of moisture. Sadly, your plant often loses water due to natural phenomena like evaporation.
Sawdust mulch can help to retain your soil’s moisture by protecting its outermost layer. This protection significantly reduces the rate at which water evaporates from the earth and prevents soil cracks that may expose and dry roots.
Sawdust also increases the moisture-retaining capacity of light soils.
Sawdust Mulch Retains Nutrients
Nutrients are highly essential for plant growth. Some of these nutrients plants require include:
- Nitrogen
- Potassium
- Phosphorus
- Calcium
Sawdust mulch helps soil to retain these nutrients.
Additionally, mulching soil with sawdust will help it become softer, crumbier, and more fertile than if you left it bare. After the sawdust decomposes, it will provide the vegetable garden with essential nutrients to facilitate plant growth.
The sawdust contains helpful nutrients like oxygen (5.2%), Nitrogen (0.9%), and cellulose.
To check soil nutrients, I recommend using the Bluelab Combo Meter Plus (available on Amazon.com). It’s a handheld device that helps you to measure nutrients, temperature, and pH levels. This device can also accurately measure how much your plant has grown within a period.
Sawdust Keeps the Soil Cool
The temperature of any soil significantly determines how fast and well plants thrive. The soil’s exposure to varying drastic temperature changes might affect your plant’s ability to survive and even reproduce.
I recommend using sawdust as mulch to combat drastic temperature and weather changes, especially during summer. Sawdust acts as a protective layer against the sun’s harsh rays and the water’s string currents. It even helps the water from rainfall move faster and more efficiently into the soil.
When it’s time for the harvesting season, the sawdust will provide you with a path to walk on, preventing you from muddying your boots and shoes while reducing the risk of accidents.
Mulch Prevents Erosion
All soils will suffer from erosion if left bare, no matter how densely packed their molecules are. When the top layer of soil in your garden is lost, it becomes much harder to grow vegetables. Ultimately, when it’s time for harvest, you’d realize that it has yielded much less than you expected.
As seedlings grow, the extreme erosion pressures can wash all of them away from your garden.
Fortunately, the thick and sturdy nature of sawdust will protect the soil against the harsh effects of erosion. Remember to add a few layers of sawdust and sprinkle some water on top to keep it in place. The best part about sawdust is that it can remain a protective layer for years.
How To Apply Sawdust to a Vegetable Garden
There’s no right way to apply mulch to soil, but the steps below have proven to be one of the most effective ways to do this. However, you can use a variation of these steps if you think it’d be more effective.
Here’s how to apply sawdust to a vegetable garden:
- Apply a light layer of sawdust
- Add another layer when plants have germinated
- Add another layer when vegetables are two inches high
Let’s see how this process will work out in practice.
1. Apply a Light Layer of Sawdust
The first thing you need to do is apply a light layer of sawdust. This step is critical when some or all of your vegetables are in the germination stage. The light layer promotes the germination of seeds while retaining as much soil moisture and nutrients as possible.
2. Add Another Layer When Plants Have Germinated
After the plants have grown to a certain extent, add another layer of sawdust mulch to retain soil moisture further. Lightly spread sawdust on the soil with your hand across the vegetable garden. Typically, this layer should be enough to kill many stubborn weeds.
3. Add Another Layer When Vegetables Are Two Inches High
Add an extra layer or two as soon as the vegetable seeds have grown about 2 inches (5 centimeters). At this point, your sawdust mulch should last you quite a while before it starts to decompose.
At this stage, manually remove all weeds that managed to break through the mulch.
Weeds less than 1 inch (2.5 centimeters) tall will die out due to the 2 to 3 inches (5 to 7.6 centimeters) mulch layer you’ve placed on the soil.
However, the vegetable may fail to break through and die before it reaches the surface if you add a thick layer of mulch (anything above 3 inches or 7.6 centimeters) before its germination process is complete.
Potential Dangers of Using Sawdust for Mulching
As beneficial as sawdust mulching is, it poses some downsides when not applied correctly. If you’re not careful, the presence of sawdust will deplete the amount of nitrogen in the soil.
Sawdust tends to suck in nitrogen from the soil when decomposing because it has an extremely high concentration of carbon—typical of wood.
Over time, the amount of nitrogen in the soil will not be enough to grow any plants, which may cause your plant’s foliage to droop and yellow. Even if you harvest them successfully, your vegetables won’t taste as good as expected.
Eventually, this deficiency of nitrogen will lead to plant death. It becomes even more of a problem if you put the sawdust into the soil, as it will hasten the depletion of the much-needed nitrogen your vegetables need to thrive.
If you want to solve this, I recommend using a Nitrogen fertilizer. The Cesco Solutions Urea Fertilizer (available on Amazon) is a good option. This fertilizer contains highly concentrated urea, which includes a rich amount of nitrogen.
You can directly apply this fertilizer by hand or by using mechanical tools. Alternatively, you can dilute nitrogen fertilizers in a solution before applying them to your mulch or soil.
However, try as much as possible while applying these fertilizers to avoid using them on your vegetables. They contain chemicals that may harm plants when they come into direct contact with them.
Remove any fertilizer that drops on plants and leaves by spraying with water—otherwise, you may notice some plant damage.
Upon frequent usage, it will significantly boost your vegetation’s development, regardless of the presence of sawdust mulch. Make sure to apply this fertilizer to the soil and mulch when needed. By doing so, your vegetable garden will have enough protein material to grow appropriately.
That said, be careful when handling mulch dust, as it can cause short-term or even long-term respiratory distress. For more information, check out my comprehensive article discussing the health hazards of mulch dust: Can Inhaling Mulch Dust Make You Sick?
What Kind of Sawdust Is Better as a Mulch?
There are two types of sawdust when it comes to sawdust mulch preparation—fresh and old sawdust. Although old sawdust is easier to obtain, fresh sawdust lasts much longer.
However, old sawdust becomes humus and decomposes faster than fresh sawdust. Also, it sucks a lot less nitrogen from the soil when compared to fresh sawdust.
Conclusion
Sawdust is a beneficial mulch to add to your soil when applied correctly. Contrary to popular belief, it is not directly harmful to your plants and garden. To combat the problem of nitrogen deficiency, use some nitrogen fertilizers when needed.
Alternatively, you can rapidly age the sawdust by adding some compost. Remember to refrain from applying too much mulch and fertilizer. Adding too much mulch will make the soil retain too much water, leading to fungal and bacterial diseases.
On the other hand, adding too much fertilizer will cause improper plant growth with an underdeveloped root system to boot.
