Do you have slate chippings in your garden? I’m sure that when they were new, they looked great. However, over time, slate chippings can become stained or covered in algae or other dirt and debris. When this happens, it’s important to clean the slate chippings to keep your garden looking its best. Cleaning them can seem like an arduous task but I assure you that when you break the job down into its basic steps, the job then looks a little easier.

Slate Chippings
Affiliate Disclosure

What are Slate Chippings?

Slated chippings are a type of mulch made from bits of slate rock. Slate is a metamorphic rock that is made up of clay, mica, and quartz. It is created when shale undergoes a change in pressure and/or temperature. From a gardening perspective, slate chippings are used for a variety of purposes:

  • Decorative Mulch: They are often used as decorative mulch in gardens and landscaping projects. Their distinct colour, which can range from blue-grey to purple and green, adds visual appeal to garden beds and borders.
  • Weed Suppression: When laid over a weed-suppressant membrane, slate chippings can help to reduce the growth of weeds by blocking sunlight and preventing weed seeds from reaching the soil.
  • Moisture Retention: Slate chippings can help retain moisture in the soil by reducing evaporation, which is beneficial for plant health, especially during dry periods.
  • Pathways and Patios: They are also used to create pathways, patios, or seating areas within a garden, providing a stable and aesthetically pleasing surface that complements the natural environment.
  • Drainage: Slate chippings can improve drainage in soil when used as a top layer, as they allow water to trickle down through the layers of slate to the soil beneath.
  • Alpine and Rock Gardens: They are particularly popular in alpine and rock gardens, where the slate can mimic the natural rocky habitats that these plants would grow in the wild.
  • Fish Ponds and Water Features: Slate chippings are also used around ponds and water features, not only for their appearance but because they are inert and won’t alter the pH of the water.

How to Clean Slate Chippings?

Cleaning slate chippings is a relatively easy process that can be completed in a few simple steps. The key to keeping your slate chippings looking their best is to clean them when they become extremely dirty. Here are the steps you need to follow to clean your slate chippings:

What You Need?

  • Garden Sieve (Riddle)
  • Shovel
  • Wheelbarrow
  • Soft Brush
  • Jet Wash

Step 1 – Move the Slate

The first step to cleaning your slate chippings is to move them to a wheelbarrow or spread them on a path or concrete surface. This can be a heavy task, so you may want to enlist some help. This will not only help to loosen the dirt and debris that has become stuck to the slate, but it will also leave you a nice clear area to work with once the slate has been cleaned.

Note: Use this opportunity to do some weeding or replace any membrane that is damaged or worn.

Step 2 – Riddle

It’s a dirty job, but someone’s got to do it. Shovelling slate chippings onto a sieve and giving them a good shoogle is the best way to clean them. The process can be messy, but it’s worth it in the end. The next step is to shovel some of the slate chippings onto a sieve. Then, give the sieve a good push and pull until all of the dirt and debris has been removed from the slate chippings. We recommend a metal garden riddle (Amazon link – opens in a new tab) with interchangeable mesh inserts so you can screen the chippings to the right size. This tool is not only useful for cleaning the slate, but it is great for other jobs in the garden such as removing stones and screening soil.

If you were only loosening any clumps of soil from your chippings, sieving alone may be sufficient. If, however, your slate has started turning that awful green colour, you may want to give it a proper cleaning.

Step 3 – Wash (Optional)

Depending on the reason for cleaning your slate, you will want to give them a good clean. Here are 2 ways that you can do this.

Power Wash

Power washing slate chippings can be an effective way of removing dirt and debris from the surface of the stone. However, it is important to take care when using this method, as excessive pressure can damage the fragile stone.

In addition, power washing can also strip away any sealant that has been applied to the slate, making it more susceptible to staining.

Soapy Water

Scrubbing your slate chippings is certainly the most laborious way to do it although it is very effective. The best way to do this is to mix mild dish soap with warm water and gently scrub the chippings with a soft brush. Once they have been thoroughly cleaned, Rinse the slate chippings with clean water and allow them to air dry.

Step 4 – Re-spread the Slate

Once you cleaned the slate chippings, you can reuse them. You can put them back where they were, or you can use them for your other intended purpose.

Step 5 – Clean Up

Now that your slate chippings are all clean, you can sweep the area to get rid of the dirt and debris that was removed from the slate. Now sit back, have a cup of tea, and enjoy your handiwork!


So, how do you clean slate chippings? To clean the slate chippings, you should start by spreading them out on a path or concrete surface to loosen dirt and debris. You can then take a large sieve (riddle) to help remove stubborn stains and dirt from the slate chippings. Finally, you can shovel the slate chippings onto the sieve and give them a good shoogle to remove all remaining dirt and debris. After cleaning, your slate chippings should be ready for use in your garden again.

How to Clean Slate Chippings - Infographic

Garden Doctor Tips

“Whilst the slate is in the wheelbarrow, it is a good idea to replace any damaged membrane!”

“It is a good idea to enlist some help, if however, you cannot, you may want to spread this job over a couple of days!”

“Make sure that you use a soft brush to clean the slate – slate chippings are quite brittle and are easily damaged!”

“Ensure your path or area where your slate is, has drainage, if the slate is sitting in water too much, it will quickly stain!”

Frequently Asked Questions

Can you power wash slate chippings?

You can power wash slate chippings, but you need to take care not to damage them. Make sure the pressure washer is set to a low enough setting so that the water doesn’t blast the chippings away. Also, be careful not to get the water too close to the house, as it could seep in and cause damage.

Does pressure washing damage slate?

Pressure washing can damage the slate if it’s done incorrectly. If the water pressure is too high, or if the wrong type of cleaner is used, it can strip away the protective sealant and cause the slate to deteriorate.

How often should you clean slate chippings?

The good thing about slate chippings is that they don’t usually need to be cleaned very often depending on drainage and other factors etc. so, it’s best to clean slate chippings as needed. If they get too dirty, they can harbour bacteria and other organisms that can be harmful to pets.

How do you keep slate from turning green?

The green colour is usually caused by a reaction between the slate and the minerals in the water. This reaction can be reduced or prevented by sealing the slate with a sealant or coating or providing drainage, so the slate is not sitting in water too long.


Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.

More You Might Like