Last Modified: April 2, 2024

​Slate Mulch

Natures Contemporary Superior Weed Solution

Garden with slate mulch

By Ben Parrot - Landscape Gardener & Amateur Geologist


When it comes to transforming your outdoor space into a captivating oasis, few landscaping materials hold as much allure as slate. Every garden has its unique charm, and with high-quality slate chip mulch, you can enhance its beauty and functionality, enjoying the benefits of weed suppression, moisture retention, and more.

In this article, we delve into the art of mulching with slate chippings; its many advantages and benefits, and why it's a superior material for gardeners and landscape designers, alike.

Oh, and don't forget to explore our 'Pebble Picker' tool, located in the sidebar or menu. This allows you to effortlessly select and compare various decorative aggregates, based on their colour and type.

Spring bulbs growing up through slate mulch. Jpg

Slate Chippings: A Different Type of Mulching

Slate chippings are universally renowned for their versatility and aesthetic appeal. As a decorative aggregate, the enchanting colours of blue, grey, black, green and plum slate make up a collective of chippings that can transform your outdoor spaces, aesthetically, like no other material can. From defining a features edging, to creating colourful borders, the natural beauty of slate can enhances landscape design.

Yet, did you know that it is also an extraordinary type of mulch?

Grey chippings around a treet trunk

Slate Chippings Are the New Bark

Slate mulch chippings have recently emerged as the contemporary alternative to traditional bark mulch. For one thing, it offers a fresh and stylish approach to landscaping that is also super low-maintenance. Unlike bark mulch, slate offers another level of enduring durability.

For example, once laid around trees and shrubs, slate can suppress weeds and help soil to retain water, for many, many years, and a darn sight longer than organic materials. Plus, unlike bio-degradable alternatives, such as bark or hay, it's permeable nature makes slate perfect for putting around water features and areas prone to dampness.

Lastly, while a stone mulch can perform as well as any inorganic mulches, when it comes down to it, because it is natural, it won't leach harmful residues into your soils, or need replacing anywhere near as often.

Garden border with rockery
Slate garden with ornamental grasses
Blue grey chippings border with shrubs

The Benefits of Stone Mulch

The Most Time-Saving, Virtuous Way to Suppress Weeds

Slate mulch is a robust barrier, suppressing weeds effectively while allowing your plants to grow, unhindered. Say goodbye to the lost hours you once spent plucking out pesky weeds, and hello to the quarterly waltz, pulling out the unlucky few that had taken root in some gaps between the blue slate chips! Too easy!

Conservation of Water

Maintaining optimal soil condensation is crucial for the health of your plants, especially during dry spells. Slate mulch excels at slowing water evaporation, reducing the need for frequent watering and promoting the sustainable growth of your greenery.

Blue slate chippings close up

Need to work out how many slate chippings your  project needs? Try our free gravel calculator.

Low-Maintenance Garden Borders & Water Features

Slate mulch doesn't just stop at practicality; it opens doors to imaginative landscaping, in colour. Design garden borders that elegantly contrast as they delineate your flower beds and pathways. The natural, earthy tones of slate provide a striking distinction against the vibrant colours of your spring bulbs, summer flowers, and perennial shrubbery, creating an eye-catching spectacle that is also working non-stop, for you.

An Elevating Element Around Driveways, Flower Beds...

Utilising slate as a mulch transcends an old orthodoxy mired in a past - a past mired with weeds and back-breaking maintenance. Instead, why not upgrade your driveway's look by edging it with a plum slate chipping mulch that will instantly infuse a symmetry and sense of order that will endure for years with little effort.

How about transforming the aesthetic appeal of your flower beds by installing a stunning blue slate chippings backdrop that emphasizes their natural beauty and puts and end to endless weeding? The possibilities really are endless, with your creativity the only limitation.

Plum slate mulch in a plant pot. Jpg

How to Lay Slate Mulch

Now that we have explored many of the benefits and uses, its time to consider the quality of your installation, as it will determine its functionality, and ultimately, its durability.

But first, a short message from Outdoor Aggregates, with a safety precaution.

Slate & Dust Makes Gloves & Mask A Must!

It is important to avoid breathing slate dust, so you should always wear a minimum FFP1 dust mask, especially if you are handling any significant quantity.

Should you find yourself caught without a good quality mask, another solution is to first soak the pile of slate mulch with water. It's still less than ideal, but don't worry, dust can’t fly.

Also, slate chips feature sharp edges, so it's advisable to don protective gloves in order to prevent any potential injuries, ensuring a smoother application process.

Laying plum chips onto landscaping fabric

Time To Lay It All Down!

As opposed to building a path with chippings, using slate as a mulch has a lot more room for error. However, here are some tips for the installation of a mulch border, built to last:

  1. Define the area where you plan to spread the chippings using a string or a rope.
  2. Dig the area to a depth that is suitable for the size of the chipping. A minimum depth of about 4-5cm is preferred, and more for larger, 40mm slate chippings.
  3. Then, it's a good idea to lay a weed membrane to really keep weeds at bay.
  4. After the groundwork is complete, make small piles of every 30 to 45 cm, and rake the chippings to level.
Laying weed fabric around plants. Jpg

However, it all really does depend on the type of ground cover you want. If you just want a pretty effective topping, which will still look great and slow weeds down, you may not need to dig deep at all. Just enough to create a lip to hold them in place.

Also, a weed membrane is also optional, particularly in small and casual settings. In these situations, even some thick cardboard on top of the dirt will work wonders for more casual plots.

We provide comprehensive step-by-step guide on how to lay slate chippings, offering an in-depth, alongside a downloadable set of instructions for members. Check it out.

Weighing down heavy duty weed membrane. Jpg

Purchasing Slate Mulch

The decision to order multiple bulk bags, a single bulk bag, or to collect a smaller quantity from a store largely depends on the scale of your project. Head over to our free gravel calculator for a quick and easy estimate of what your project will need, particularly if you are planning some large borders, or even work as a professional landscaper. It's fast and free!

Most people prefer to buy stock from a website, and after placing an online order, have their decorative aggregates delivered. Several suppliers offer a tail lift vehicle for easy bulk bag delivery, but it might not be suitable for all residences or postcodes, especially where driveway access is restricted.

Delivery typically takes 2-3 business days. Be mindful of delivery postcode limitations and use a delivery postcode checker to verify if your area is eligible for delivery.

Mulched garden border around the base of a mature tree


The allure of slate mulch goes well beyond its captivating aesthetics by bringing a range of low-maintenance benefits that cater to homeowners, gardeners and landscaping professionals alike. With its weed suppression capabilities, moisture retention powers, and characteristics that can transform ordinary spaces into eye-catching havens, there is no sense in not utilising the ultimate outdoor aggregate solution, slate mulch.

1ornamental slate garden with fence border


Is slate a good mulch?

Reduce weed germination – weed membranes may also sit under slate to prevent weed growth. Ideal as an organic mulch slate helps retain moisture and cool soil and helps plants survive hot climates.

What is plum slate mulch?

Plum slate mulch is a captivating landscaping material known for its deep and alluring hues of purple and blue. This versatile decorative aggregate not only adds an elegant touch to gardens and pathways but also serves functional purposes like weed suppression and moisture retention.

Will slate chippings stop weeds?

Crushed gravel is commonly used for mulching around the plants to prevent the growth of weeds. They provide a nice contrast of colors in plant foliage as well. Landscape borders are used to form borders around gardens or pathways by using slate.

There are many other colours of slate chippings available for your project. Check out them out!

About the author 

Ben Parrot is a landscape gardener and amateur geologist. He is the founder of Outdoor Aggregates, with the mission to create the first encyclopaedia for decorative aggregates. From natural stone through to decorative bark, these aggregates are critical to garden and landscape design, universally.

The problem: There isn't any place where all the different types of decorative landscaping materials and construction aggregates can be found, nor are the specifications of each type readily available. So, enriched by his extensive experience, and inspired by the timeless elegance and raw beauty of stone and rock, etched by nature's artistry over millennia, Outdoor Aggregates was born.