Whether you’re building a new garden or neglected your old garden for one season too long, you’re likely ready to spruce it up with mulch. But if your garden has a lot of stones, you might wonder whether you need to remove the rocks before mulching.
Putting Mulch Over Rocks: The Answer
In some cases, it’s okay to put mulch over stones. Small stones often serve as an aid to mulch, as they help with the following:
- Reduce weed growth
- Prevent soil erosion
- Improve drainage
- Protect plants from pests
But it’s not all sunshine and roses (pun intended). Since rocks speed up heat absorption from the sun, they can kill beneficial microbes and nutrients in the soil. As a result, your plants may become stressed and malnourished.
Furthermore, many types of rocks raise the pH of the soil, making them more alkaline.
So, if you have plants that need more acidic soil—which is the case for many plant species—it’s best to remove the rocks.
The bottom line is that if you live in a cool climate and have plants that can tolerate a higher pH, you likely won’t damage them by mulching over rocks, and you might even help them.
Can You Put Rocks Over Mulch?
You can put rocks over mulch so long as you don’t place the stones too close to the plant’s stems. The plants also must be tolerant of moist soil, as stonmes are porous as long as the pores are connected and will aid mulch in retaining even more moisture.
Should you choose to put rocks over mulch, we recommend starting small by following these steps.
- Select a small place in your garden and install a landscaping fabric.
- Lay down your mulch and place some rocks over it.
- Give the plants, rocks, and mulch a good watering.
- Wait to see how long it takes for the soil to dry.
If the area around the rocks and mulch dries within two days, you can assume it’s safe to use stones in your garden.
Is It Better To Remove Rocks?
It depends on the situation to determine whether removing rocks before mulching is better.
If you’re dealing with small rocks that are a natural part of the soil, there’s likely no need to remove them. Instead, test the soil’s pH, put your mulch down, and grow plants compatible with the soil’s makeup.
Alternatively, removing the rocks before mulching is best if you live in a hot climate or have plants that can’t tolerate excessive moisture.
Using Rocks as Mulch
Some people use stones or gravel instead of mulch for their gardens. Doing so isn’t the right fit for all situations, but it’s worth considering if you have issues with water pooling in your garden.
Rock mulch is also low maintenance once you lay it down, although it has a high initial up-front cost.
Generally, rocks are better suited for mulch around bushes and other hardy vegetation than flower and vegetable gardens.
The Advantage of Mulch
Most mulch comes in an organic form that naturally breaks down over time. Therefore, it offers an excellent opportunity for plants to receive a slow and constant source of nutrients.
In contrast, stones provide little nutritional value to plants and can ultimately harm them by changing the soil’s pH levels.
So, when in doubt, it’s almost always best to use mulch instead of, or in addition to, stones.
Final Thoughts
Every garden is unique, so there’s no one size fits all solution to rocks and mulching.
If you’re unsure how to mulch your garden, we recommend experimenting with a small area to see how your plants respond.