Top soil, compost and bark chippings are all essential materials for garden projects, from filling a garden planter to laying a new lawn or flowerbed. Here's our handy guide to selecting the right product for your project.
What is top soil?
Top soil (or topsoil) as its name implies is the rich layer of soil normally found between 5 and 10 inches from the surface. It is a combination of mineral particles, organic matter, microorganisms, water and air.
Top soil can be mixed with the existing soil in your garden to improve its quality, or used for the creation of new growing areas such as a new flowerbed or raised bed. In brand new properties it may be necessary to apply top soil to the garden, as the subsoil from the foundations may have been spread over what is now the garden.
When top soil is sold commercially it will have been tested to several British Standards to ensure its quality, consistency and provenance - don't be tempted by adverts for 'cheap top soil', more often than not this will be low grade sub-soil that has come from a building site!
The basic constituent of quality top soil comes from sustainable greenfield or agricultural sites, where it is harvested and then carefully processed to give a consistent product - additives such as sand or lime may be added to balance the consistency or pH of the soil, before it is sieved to remove large stones and other matter.
Top soil is graded depending on its consistency, so a fine top soil like Melcourt Extra Fine Top Soil would be suitable for applications such as laying a new lawn, whereas Melcourt Blended Loam Top Soil would be more suitable for new flowerbeds or raised beds.
What is the difference between top soil and compost?
Before we look at the difference between top soil and compost, we need to clear up the difference between compost and garden compost. Compost or potting compost is a medium that can be used to grow plants in containers or pots. Garden compost is the rotted down matter from a compost heap which is applied to the soil to increase its organic matter - you would never use garden compost in pots or planters.
Compost or potting compost is essentially a high-grade manufactured super soil, containing an exact combination of organic matter, sand and grit, fertilizer and lime. Different brands of compost will have their own unique formulation, and composts for specific uses will have different consistencies.
For example, seed compost will have a very fine structure to allow seedlings to germinate, whereas a container compost may include water retention ingredients to reduce water loss, or slow release fertilizer to stimulate prolonged growth.
Compost or potting compost will also tend to have a higher nutrient content than top soil, and may have been sterilised to remove any weeds or plant diseases. Hence it is recommended to always use a potting compost for planters or pots where your plants have a limited amount of room to grow.
Top tip - always buy more compost than you think you'll need, there's nothing worse than running out halfway through filling a planter. Any extra can be stored away until you need it again.
What is peat-free compost?
Peat is a naturally occurring form of organic matter, formed from decaying plant matter in peat bogs over thousands of years. It was widely used in gardening and in composts until the environmental impact of harvesting peat was recognised. Hence the use of peat is now being phased out in garden products and will be banned from 2024, and many gardeners already make the decision to choose peat-free products.
Modern composts, such as Westland New Horizon Compost, use sustainable organic matter such as coir in place of peat to produce high quality, high performing potting composts.
Using bark chippings in the garden
Bark chippings are a wonderful organic medium to use in the garden, and have two main uses:
- ornamental bark to cover beds and borders, suppressing weed growth, protecting from frost and reducing water loss (mulching)
- play bark to act as a soft surface around children's play areas
Bark chippings used for mulching flower beds or vegetable gardens tend to be a smaller size than those used for children's play areas, and are usually laid over a weed suppressing membrane on soil to suppress weed growth, and to conserve water.
If you're laying landscape bark on a completely empty bed, then it's simple to cut a cross in the membrane once laid, dig a hole for your plant then replace the membrane and bark.
To add a layer of mulch to an area that is already planted then the process is slightly more complicated, laying a patchwork of membrane pieces to fill the gaps between plants, then dressing with bark. For sloped areas it's also recommended to use fixing pegs to secure the membrane.
An added benefit of bark mulching is that it provides an ideal environment for wildlife, especially insects, to live in your garden.
Finer grade bark chippings to top dress pots and planters are also available.
Bark chippings for play areas
Bark chippings for children's play areas, or Playbark, are manufactured to a higher grade than bark mulch, with larger bark pieces, and any dust or fines removed. Lay between 100mm and 200mm of playbark to cushion a fall of between 1.33m and 3.82m respectively.
How much top soil, compost or bark do I need?
Calculating how much material you will need can be confusing, as smaller bags tend to be sized in litres, whereas larger bulk bags are sized in m3. As a general rule, our bulk bags are 0.6m3 which equates to 600 litres of material. 1m3 equates to 1000 litres.
To make your calculation easier measure your space in metres, then multiply by the required depth of coverage in metres. For example:
Area is 2m x 6m = 12m2
Required depth of material is 10cm = 0.1m
Material required is 12m2 x 0.1m = 1.2m3
1 bulk bag is 0.6m3 so you will need 2 bulk bags
If you are filling a pot or planter, then a 50cm x 50cm x 50cm planter is 0.5m x 0.5m x 0.5m = 0.125m3
Convert m3 to litres by multiplying by 1000
0.125 x 1000 = 125 litres
These calculations are all approximate as different types of material settle differently - a good rule of thumb is always to order more material than you think you will need. Alternatively ask the staff at your local branch of AVS to calculate how much you will need for your project.
Ask the experts
For further advice about your garden project don’t hesitate to speak to our friendly and knowledgeable experts at your local AVS Fencing & Landscaping Supplies branch. Our ranges of top soil, compost and bark are available from stock subject to availability, click and collect from your local AVS Branch or home delivery within our AVS Branch delivery area.