Covering mulch with a tarp is the best way to keep it dry during heavy rain. This is important if you plan to spread the mulch out in the next 1-2 days as wet mulch becomes heavy. On dry days, do not cover mulch with a tarp to allow air movement to keep mulch temperature down.
Avoid covering the mulch with a tarp if the mulch pile is steaming as it could overheat.
Covering mulch with tarps
Mulch can be covered with a tarp if you plan on leaving it in your yard during rain. Keeping mulch dry is the best way to make it easy to move and keep it light. It is best to wait for a dry weekend before getting large amounts of mulch delivered as wet mulch is sticky, heavy and more difficult to move.
Covering a mulch pile with a tarp will help to slow the breakdown process. Mulch including bark mulch needs water and bacteria to break down. Make sure the pile keeps cool and smaller piles will work best to keep them cool and dry.
Tips for covering mulch with a tarp
Make sure there is air movement
When placing a tarp over mulch allow air movement around the sides of the mulch pile. This will help to ensure that if it starts to break down that it can cool off.
Place the mulch pile in a shaded position
Place your mulch pile and tarp covering in a position in your yard that is as shady as possible. This will help to keep the mulch pile cool and reduce the rate at which it breaks down. Mulch can heat up quickly if it is in the open sun and begins to break down.
Check the mulch pile regularly
Check the mulch pile regularly and if you see steam coming from the pile, it is best to remove the tarp. Mulch piles can heat up quickly so remove the tarp and allow more air movement. Make the pile smaller by spreading it out thinner or place it out in your garden in to your garden beds.
Pin the tarp down with tent pegs or use heavy rocks
To avoid the tarp blowing away, pin down the corners with large tent pegs. This works if you are placing the mulch pile on top of soil. Mulch piles that are placed on top of concrete or paving, use heavy rocks to hold the corners of the tarp down. You may also want to place a rock on top of the mulch pile to keep the tarp in place.
Use the mulch as soon as you can
The best way to keep mulch fresh, clean and looking great for your garden is to use it as soon as you have it delivered. Mulch is best when it is placed on your garden beds as soon as possible as it will be bright, light and easy to handle.
Mulch after you have heavy rain to allow the water to penetrate through the soil. Organize to have mulch delivered after the rain and lay it on top of the soil. The mulch will absorb any excess water as well as preventing too much evaporation on hot sunny days.
Fresh, dry mulch is easy to move using a large mulch shovel. These are light, durable and a great way to spread mulch around your yard.
Should I put a tarp down for mulch delivery?
Place a tarp down if you are planning to get mulch delivered on your driveway or a paved area. Placing a tarp down will make it easy to clean up the last pieces of mulch after you have spread the majority around your yard.
This works well for bark mulch as you can simply grab each corner of the tarp, lifting up the last few pieces of mulch and tip them onto your garden beds.
This is also a great idea if you have to have mulch delivered on your lawn. Having mulch delivered onto a tarp will help to keep all bark and leaf pieces off your lawn. Bark mulch is easily cleaned up off a tarp and will avoid pieces falling into your lawn and getting caught in your mower.
How to protect mulch
Mulch piles can be protected from large amounts of rain using tarps. Make sure there is still air movement around the edges and remove the tarp after the rain has passed. This will make sure that the pile does not heat up too much under the tarp.
Natural mulches will start to break down and can even steam if they are in large piles. This is the process of the soil microbes breaking down the mulch. Reduce the heat in your mulch pile by making the pile smaller or spilling it into two piles. You can also spread it out over your yard.
How long can you keep bagged mulch?
Bagged mulch will keep for 3-6 months if it is kept dry and is dry to start with. Make sure the mulch bags have air holes and if they don’t, put some in using a garden fork. Keep mulch bags in a sheltered area with lots of air movement.
Are you supposed to remove old mulch?
Old mulch does not need to be removed and can be left on top of garden beds to break down into compost and eventually humus. Put fresh mulch on top of old mulch, topping the level up to a maximum of 3 inches. This will allow rain to get through to plant roots but will also protect the soil from growing weeds.
Does mulch need to be replaced every year?
Most mulches will need to be topped up each year but will not need to be replaced. Landscaping rocks will keep well for years but often require hand weeding as weeds still push through and grow between the rocks.
Bark mulch will break down slowly over around 6 months and will need to be topped up to keep it up to 2-3 inches thick. If mulch gets thinner than 2 inches, weeds will begin to grow through as the sunlight can reach weed seeds sitting in the soil allowing them to grow.
Other uses for tarps in the yard?
Should you cover mulch with a tarp? – Summary
Cover mulch with a tarp to keep it dry during heavy rain. When there is no rain around, remove the tarp and allow air movement through your mulch pile to avoid overheating. Do not cover steaming mulch piles with a tarp, instead spread the mulch thinner or in smaller piles to cool it down or place it on your garden beds.
Bark mulch is my favorite as it lasts well, is affordable an improves your soil over time. Mulch is best laid as soon as you get it so get it on your garden and you can skip the tarp.
I am an accredited practicing dietitian, experienced gardener and a dedicated cook. I love writing and sharing my experience so you can learn from my successes and mistakes.