Updated/Fact-Chacked on April 26, 2023 by Gareth James
If you are struggling to keep on top of your weeds and don’t like the look of wood chippings, slate chippings could be the answer. We use them at the side of our patio where our passion flowers are planted.
Slate chippings look stylish and can act like a hard mulch around plants; they suppress the number of weeds growing and provide soil drainage. Also, slate will not change your soil structure like some wood chippings do as they break down.
Here’s an overview of how to lay slate chippings in your garden; I also included the different types of slate chippings available and the best places to buy them.
1. Choose an area and a design
Determine where you need your slate chippings to be and how you want them to look. You can make a garden path, driveway, planting areas, or borders using slate. You also need to think about the colour and size of slate chippings, see our FAQ below.
Here’s a few exquisite designs for you to think about. You could create a Pinterest board of all your favorite.
Slate and paving used together can look very sleek
Slate used on borders to help with weeds and provide a backdrop for plants
2. Calculate the quantity of slate chippings needed
All you need to know is the size of the area (length x width) and the depth of the slate required – most slate layers are around 5 cm deep. Once you have these measurements, search Google for a ‘slate chipping calculator‘ to give you the number of bags/KGs you need to buy.
Slate chippings are available from most stores like The Range, B&M and Homebase. They are sold in small 20kg or you can buy large heavy-duty bags which should work out cheaper. Homebase sell 750KG bags with delivery.
If you’re still unsure of the quality required, take your measurements to the store you are buying from and ask for advice.
3. Prepare the area
For this step, you’ll need a string or a rope, a flattening tool, and a material to be used as a border.
Use the string or the rope to mark the area where you’ll lay the chippings. Dig around 5 inches into the soil to remove turf, grass, and plant roots, then rake the base into a smooth surface using a flattening tool.
You might wish to use bricks, wood, or stone to create a border around the area, so it stays intact and doesn’t affect nearby greenery.
4. Lay the base
You need to use a thick weed membrane to prevent weeds from sprouting through the aggregate. For my border, I used Groundmater 1M X 10M heavy duty on Amazon; it comes in various roll sizes and has been excellent. It’s been 3 years since I laid my slate, and it’s still holding strong.
- garden membrane for slate
5. Lay the slate chips
Now that your base is ready, add the chips over the weed-resistance membrane and use a rake to distribute the chippings equally. Once complete make a cup of tea and admire your work, it should look fantastic.
Problems with Slate Chipping
My main gripe with our slate chippings is the collection of plant debris, see image below. This was partly my fault though as I gave our passion flower a hard cutback in spring without laying some plastic sheeting to catch it all.
Best places to buy slate chippings
Your best bet is to go to your local building merchants for the best price possible. I’ve just compared a few shops locally for 40mm blue slate and here is a comparison on a per KG basis.
Travis Perkins – 0.20p/KG (buying a 800kg bag)
The Range – 0.22p/KG (in 20kg bags)
Homebase – 0.42p/KG (19KG bags)
Slate Chippings FAQ
How much do slate chippings cost?
You can buy large bags of Welsh blue slate for £12.99 per bag on Amazon, these also save you carrying heavy bags to and from your car.
Can I use slate for my driveway too?
This is not recommended, as the chipping tend to grind down quicker than hard-wearing stones.
Can I use slate in my outdoor potted plants?
Yes, a slate topping will help the pots retain water better, ideal for plants like hostas that love damp conditions.
What size slate chippings can you buy?
Slate chippings are generally 20mm or 40mm, with 40mm being standard. The 20mm slate chippings are used for paths as they have a less jagged shape.
What colours do slate chippings come in?
You can get these chippings in dark grey, blue and green colours. I used the blue slate.
Can slate chippings help with weeds?
Yes, like bark, slate will help prevent weeds from coming through. We recommend the slate mini mulch.
Will slate chippings on my borders affect my soil PH?
No slate chippings will not affect the PH of your soil.
Mary shares a passion for gardening with her husband John, though she is more focused on growing veg on their allotment at St. Margaret’s Allotments, Durham. Mary also works in the lawn care industry and manages the lawns for the Durham University campus.