Downspouts can wash away light mulches so heavy mulches like landscaping rocks are the best choice for these areas. Use a mix of mulch types around a down pipe starting with rocks, moving to larger bark chips and small bark chips for the perfect mix. Light mulches like a mixed bark mulch can wash away during heavy rain, cause soil to wash away and can damage plants.
Landscaping rock is the perfect mulch to use underneath your downspout and there are simple ways to lay rocks so they look great, protect your plants and will prevent other mulch types from washing away.
I had planted my Star Jasmine right near an area of my downspout that overflows during heavy rain. To solve the problem of the mulch washing away, I placed large landscaping rock, then surrounded this with smaller rock. I could then place a bark mulch around the Star Jasmine to protect the soil and prevent weeds.
Downspouts vs downpipes
For those of you that may be wondering what the difference between a downspout and a down pipe is, a downspout is the pipe leading down from your gutter with an open end, a downpipe will connect under the ground. Check out more detail below.
Downspout
This is the pipe that joins your guttering vertically down to the ground. It will have an open end that will flow down to a drain or drainage area which will be sloped away from your house.
Downpipes
Downpipes are similar to downspouts as they are the pipe that connects your guttering down, but a downpipe will connect under the ground. This is usually connected to a pipe that leads under the ground to the gutter.
Garden edging for downspouts
Garden edging the best way to stop mulch washing away under downspouts. Edging choices include:
- Hardwood timber edging
- Treated pine edging
- Stainless steel flexible edging
- Paving
- Larger rocks
- Plastic edging
Each of these choices will hold mulch in the are underneath your downspout. A chain can be used to direct the water down to the rock area, or simply allow the opening to land on the rocks.
Drainage near downspouts
The water must flow somewhere after it reaches your mulch from your downspout. This means there will be a drain pit leading to the curb installed underneath the soil from an open down pipe.
Clean your gutters to save your mulch
Another important tip is to make sure your gutters are kept clean to minimize the amount of water overflowing from your gutters in heavy rain. This will reduce the mulch run off and save your garden beds.
French drains can save your mulch
French drains can be an easy solution to move water away from your downspout and out another area of your garden out of the way.
A French drain is simply a sloped trench, filled with landscaping rock and a perforated pipe which can move water away from your house. Check out this video below for more on how to build a French drain and how they can stop your mulch washing away.
Using a heavier mulch like landscaping rock is key to keeping your mulch and pipes in place.
Bury your downspout
Burying your downspouts is the best way to prevent water from washing away your mulch. When downspouts open directly onto your garden, in heavy rains the water can spread further that usual. This is when mulch can be washed away.
By burying your downspout you can avoid excess water washing through and spraying further than your rock area and washing away your lighter mulches.
The other option is that your pipe will go straight into the ground, connect to drainage pipes which open onto the curb. This option will mean that the only water that should fall onto your mulch is the excess that overflows from your gutters.
Work out where your gutters overflow in heavy rain and surround that area with heavy mulches like landscaping rock or large bark pieces.
How to extend gutter downspouts
Extending your gutter downspouts to an area that is out of the way of your garden beds and mulch can help to hold your mulch in place and prevent water from pooling near your house. The best gutter downspout extensions include aluminum pipe extensions, buried plastic downpipes, splash blocks, rain barrels or flexible hose.
Downspout washing away mulch – FAQ
For flower beds that are close to downspouts using a landscape rock around the water outlet is the best option. You do not need to use rocks throughout your garden bed but using them under the area with the greatest water flow will help to keep your soil in place and protect your plants.
Garden edging like pavers, steel edging or plastic edging will hold any lighter mulches like bark or tree mulch in place and stop if from being washed out of your flower bed.
Flowers will have sensitive roots so it is important that the roots are protected from mulch and soil run off. Smaller rocks can work to hold the soil in place for plants that are very close to your downspout.
The best mulch to put under down spouts is landscaping rock which will surround an in ground drain. The rock area only need to extend to around 1 foot around the drainage area if your system is set up correctly. Larger mulches like bark mulch can form the next layer around the landscaping rock and is a great place to plant water loving plants.
Landscaping rocks, hardwood mulches and garden edging will all work together to keep mulch in place during heavy rains and run off. This will also protect your soil and stop it washing away into drains and starving your plants. Planting grasses that hold soil and mulch in place is a fantastic idea, my favorite is Tanika which is a hardy clumping grass that is bright green.
How to keep mulch from washing away on a slope
The best ways to keep mulch from washing away on a slope is to use heavier mulches like landscaping rock or mulch like bark or tree mulch which will knit together and hold in place over time. Plant grasses that will hold the mulch in place during heavy rain and stop any run off from the slope.
My downspout is washing away mulch! – Summary
Downspouts can look great if they have a solid mulch to drain into like landscaping mulch. This rock can be surrounded by bark mulch which will improve your soil and prevent weeds. Weeds love to grow near downspouts because of the excess water so you will need to protect your soil.
Hold mulch in place with garden edging for a great look or dry a French drain if you have lots of water run-off. All of these are great ways to keep mulch in its place.
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.