The Use of Slate Chippings
Posted on 15th April 2020
The amount required for your garden will vary based on stone size and area to be covered. Our bulk bag of gravel or decorative aggregate usually contains around 900kg of stone which covers roughly 10m2 of an area at a depth of 50mm/2 inches.
Quick Reference: A rule of thumb is 1000kg = 10m2 (5m x 2m) at 50mm deep.
What is slate?
Slate is a fine-grained type of metamorphic rock. Slate develops due to the repetition of metamorphic rock layering. Slate is a highly durable, strong rock, making it a popular choice for construction and outdoor landscaping.
Decorative Slate Aggregate
Slate is a completely natural product and is an extremely versatile decorative aggregate. It comes in three main colours, plum, green and the popular blue slate. It comes in a wide range of sizes and can be used almost anywhere in the garden, including plant pots, pathways, borders, rockeries, driveways and even in water features and fish ponds. Most slate can be used in or near water features as it doesn’t generally affect the pH of the water, so will be safe for use near aquatic life. Algae does not form as quickly on slate as on block paving or concrete which is a plus for using slate in wet areas.
The key benefits of using slate as an aggregate are:
- Versatile - this diverse product can be used for paths, driveways, edging, water features, rockeries and much more. There's also a wide variety of colours, textures and shapes available, allowing for broad innovation
- Easy to lay - slate chippings are a popular choice instead of a surface using tarmac, concrete and paving as they're much simpler to lay
- Environmentally-friendly - slate chippings are a recycled material and more eco-friendly than other quarried stones
- Reduce weed germination - a weed membrane can easily be laid beneath slate to block weeds emerging
- Perfect for mulch - slate is the ideal material for retaining moisture and cooling soil, helping plants to survive hot weather
- Durable - slate is hard wearing and rarely affected by adverse weather
- Gives that fantastic look - slate looks great whether wet or dry, becoming a wonderful darker shade when wet
Slate does darken in colour when wet – giving an additional feel and look to the garden that sets off the panting and colours. Slate helps keep unwanted weeds at bay by blocking the sunlight in areas where weeds are more likely to take hold. Not only does it help with weeds, but slate chipping also helps soil retain moisture too.
Slate has special properties and available in distinctive blue/grey colours, a dark blue, plum and green. A slate chipping ‘mulch’ sends light back up to lighten shaded areas or beneath vegetation. It also absorbs heat and keeps gardens and indeed soil cooler in summer than other paving
Its durability makes it a good choice for permanent schemes and as it interlocks, when using 15-30mm size, it is comfortable to walk on and use as a driveway surface material. Slate is a popular choice for driveways because it is affordable, easy to lay and low maintenance.
For sloping driveways, slate chippings are a good choice due to their shape. Slate chippings will interlock together, helping them not to disperse easily and stay in place.
Slate is chemically inert and therefore will not make the soil excessively alkaline which would damage lime-hating plants such as azaleas and camellia.
Slate chippings perform a variety of useful garden tasks such as reducing weed germination which makes for an easier life in the garden, they will help water retention of the soil, which may be particularly useful if you are gardening in a restricted space and using containers.
No matter how you choose to use slate chippings in your garden, it’s important to dig over the area you’re going to overlay and then cover it in a weed-suppressing membrane, which you should secure to the ground with pegs. Plant your chosen flowers where you want them, cutting the membrane to gain access to the soil and then carefully folding it back to create a tight seal around each plant. You should finally spread your slate chippings across the border.
Slate chippings can really enhance your garden in a number of ways from transforming a dingy backyard to helping you create attractive focal points. It also has the added attraction of providing security for the house, given the sound that emanates from pedestrian or vehicle movement. Slate is the perfect complement to an array of garden styles, including traditional gardens, minimalist, Japanese, water gardens, around free-standing water features or as a decorative topping for containers.
Other than for planting beds and pot toppings, slate is perfect paths and driveway. Just remember to edge the path with discreet plastic edging or decorative brick. This stops the soil from lawns and beds seeping into the chippings and providing a medium in which weeds could grow.
Slate Size & Usage Guide
Slate Mini Mulch
Slate mulch is the finest type, measuring typically 4 – 10mm and is ideal for use in planters, for pathways and in the garden. We don’t recommend using this for a driveway, however, as it does break easily under the weight of a car.
Chippings are typically around 15-30mm in size and can be used pretty much anywhere in the garden. If you use the larger 40mm slate chipping you can even use slate on a driveway.
Slate paddlestones measure 50-100mm and are tumbled to create a smooth finish. Due to their large size, these stones are easy to walk on and are great for an unusual garden path. They also work well in water features, as water runs across them smoothly due to their polished surface. Due to their large size, we wouldn’t recommend using these on a driveway.
The depth of your slate chippings depends on what you use them for and their size. Generally, standard 15-30mm slate chippings should be laid approximately 4-5cm deep. However, specifically for driveways, this should be slightly deeper at 5-6cm.