Do you have an old mulch layer in your garden and don’t want to remove it to grow new plants? This might leave you wondering:
Can you put soil on top of mulch?
Luckily, you may use soil on top of your mulch layer, but only if you use proportionate amounts of soil and mulch. You’ll also need to follow some other guidelines to prevent adverse effects like nitrogen entrapment.
Below, I’ll share with you my tips on using soil on top of mulch, walk you through its benefits, and answer some questions you might have.
What’s the Right Way to Put Soil on Top of Mulch?
Without knowing exactly what to do, you may unintentionally damage your garden soil when putting soil on your mulch layer. So, keep these tips in mind before you take this approach:
Choose the Ideal Soil and Mulch Type
The best candidates include topsoil or new soil—anything as long as you don’t use clay. If you do, without altering its texture by adding sand, it’ll prevent the water from reaching the roots.
For mistake-free results, my recommendation is to stick with light soil from the get-go, like sand.
You also need to consider the mulch material itself. Some high-carbon types, like shredded wood, aren’t good options for underground mulching. They tend to trap nitrogen for a longer time while they decompose.
So, you might need to replace your mulch with a low-carbon variety before adding soil on top of it.
Know How Much Soil and Mulch to Add
Remember that an imbalance of soil and mulch quantities won’t give you the benefits you’re hoping for. That’s why I always use equal amounts of soil and mulch to ensure I don’t deprive the plants of nutrients or accelerate the growth of bacteria.
To put it into numbers, you should opt for an inch-deep layer of both mulch and topsoil. If the preexistent mulch is two or three inches deep, remove the excess just to play it safe.
Ensure the Mulch Has Enough Moisture
Too wet or too dry mulch won’t do your garden any good once you start planting.
The former encourages the growth of harmful bacteria, while the latter defeats the purpose of keeping your soil adequately moist.
Carefully Press the Topsoil Against the Mulch
Once you’ve followed the previous guidelines, gently press the new layer of soil against the mulch.
Here, it’s essential not to apply too much pressure, or you might get rid of the air pockets inside the soil. This also lowers moisture levels, and you need enough moisture to grow healthy plants.
Don’t Hesitate to Add Some Water
My final piece of advice is to finish up with some water to maintain a nice level of moisture without overwhelming the soil.
Even when it’s time to plant your seeds and afterward, your plant care routine should involve checking the topsoil’s moisture. Keep it from getting too dry or cakey.
What Are the Benefits of Putting Soil on Mulch?
When done correctly, adding topsoil on mulch offers your garden a multitude of benefits, such as:
- Boosts the nutrients in your garden
- Helps warm up your soil (especially if it’s sandy) during the cooler days of spring
- Improves drainage
- Increases your garden’s ability to fight off weeds (combined with your mulch’s protective capabilities)
- Stabilizes your mulch layer, keeping it from being washed away with rain or wind
When Should You Add Soil on Top of Your Mulch Layer?
To give my garden enough time to settle before planting, I always add new soil above old mulch in early spring. By the time I’m ready for planting, the garden soil should be warm enough for the new plant roots.
If I’m feeling productive, I’ll sometimes do it in the fall.
Can You Till Mulch Into Soil?
No. Tilling mulch into your soil may cause a temporary nitrogen deficiency, which can lead to stumped growth, yellow leaves, and other unwanted scenarios.
The general rule is to layer your mulch and soil and only press them lightly against each other. Never till or mix them.
Can I Mix Mulch with Potting Soil?
Mixing mulch with potting soil isn’t a great idea either.
That’s because, when your organic mulch begins to decay, it traps the nitrogen already available in your potting soil.
As a result, the nitrogen won’t reach your plants, which hinders their growth much like tilling mulch into your garden soil.
Final Thoughts
After reading my post, now you know that putting soil on top of mulch can be a fantastic idea for healthier soil and plants.
However, this is only the case if you keep the amounts of topsoil and mulch proportionate. You should also pay attention to the moisture levels, types of soil and mulch you’re using, and other considerations for a zero-mistake gardening experience.