Compost vs Topsoil vs Soil Improver: What Should You Use in Your Garden?

After a hot, dry summer and a busy growing season, autumn is a good time to improve your soil and get beds and borders ready for next spring. Depending on the job, you might need topsoil, compost, soil improver, manure or bark mulch.

Each of these products has a different purpose and is suited to different garden tasks. The best choice will depend on what you’re looking to achieve, such as adding soil, enriching what is already there or covering and protecting the surface.

In this guide, we compare compost vs topsoil, explain where soil improvers, manure and mulch fit in, and recommend products available from AWBS to help you decide.

Quick answer: which product should you use?

As a general rule, topsoil will add volume and structure, while compost, soil improver and manure add nutrients to boost the quality of existing soil. Bark mulch, meanwhile, is spread over the surface to help retain moisture, suppress weeds and create a more decorative finish.

What is topsoil?

Topsoil is the upper layer of soil and is used when your garden needs more soil added. For example, when you’re building up a new bed, replacing lost soil or levelling an area. It also provides a base for many planting and lawn projects.

For everyday garden jobs, AWBS Blended Loam Topsoil is our most popular option. It works well for topping up beds and borders, as well as general landscaping. For new beds and planting areas, AWBS Planting Soil has a low stone content and a fine, easy-to-work texture that makes it well suited to planting.

AWBS Premium Soil contains added organic matter, providing a good growing medium for fruit and vegetables and other planting projects. If you mainly need to build up levels or cover a larger area, AWBS Value Soil is an economical recycled topsoil suited to infilling, levelling and raising beds and borders.

All four can be ordered as a topsoil bulk bag of approximately 850kg. Blended Loam, Planting Soil and Premium Soil also come in approximately 450kg half bulk bags, which may be more practical for smaller garden projects.

What is compost?

Compost adds organic matter and nutrients to existing soil, helping to improve its condition and create better growing conditions. It can be worked into tired beds and borders before planting or used to replenish soil after the growing season.

AWBS Multi-Purpose Peat Free Compost is a finely screened green waste compost designed for use as a soil conditioner or mulch. It is free-flowing and easy to work with, making it a great choice for established beds, borders and other planting areas. Sold in jumbo bags, our bulk compost covers approximately 10–12m² when applied at a depth of 50mm.

The main difference between compost and topsoil is that topsoil adds soil and builds up levels, while compost improves what is already there. For a new bed, you can use topsoil to create the main growing area, then mix in compost to give plants a better start.

What is soil improver?

Soil improver is mixed into existing garden soil to improve its structure, making it easier to work and better suited to planting. In heavy or compacted ground, it can help improve drainage, while in sandy soil it can help retain moisture. Unlike topsoil, it isn’t intended to fill a new bed or significantly raise soil levels. For these jobs, start with a suitable topsoil and add soil improver where needed.

Rolawn Soil Improver is a peat-free soil conditioner with a light, easy-to-work texture. Suitable for beds, borders and other planting areas, it can also be used to prepare existing soil before laying new turf.

When comparing soil improver vs compost, there is some overlap because both can be mixed into garden soil. Compost is generally used to increase nutrients in the soil, while improver can be particularly helpful for tackling compaction, poor drainage or low water retention.

What is manure?

Farmyard manure is well-rotted organic material that can be dug into beds, borders and vegetable plots. As it decomposes, it releases nutrients gradually, while also helping the soil hold moisture. Autumn is an ideal time to apply manure to established growing areas. Digging it in after the growing season gives it time to settle and break down before spring planting.

At AWBS, we stock Westland Gro-Sure Farmyard Manure – a rich organic compost suitable for flowers, fruit, vegetables, trees and shrubs. Available in 50-litre bags, it is a practical choice when you don’t need a full bulk bag. And right now, if you buy two bags you’ll get a third bag free, making it good value for larger beds and borders.

What is mushroom compost?

Mushroom compost is a by-product of the mushroom-growing industry and a rich organic soil conditioner. It can be worked into beds, borders and vegetable plots, or applied as a mulch to cover the soil and help prevent it drying out.

Mushroom compost contains chalk, which can help reduce soil acidity and improve growing conditions. As the RHS explains, “the liming effect of the chalk is an added benefit to soil fertility”. However, avoid using it around acid-loving plants like rhododendrons and fruit crops.

Our own-brand AWBS Mushroom Compost contains steam-sterilised horse manure, poultry manure and wheat straw. Suitable for mulching, soil improvement and general planting, it comes in jumbo bulk bags covering approximately 10–12m² at a depth of 50mm.

When should you use bark mulch?

Unlike topsoil, compost and soil improver, bark mulch is spread over the surface rather than mixed into the soil. It creates a protective covering that helps slow moisture loss, limit weed growth and insulate plant roots during colder weather. And by covering areas of bare soil, it can also give beds and borders a neater finish.

Over time, bark gradually breaks down and adds organic material to the soil below. However, its main purpose is as a surface covering, so it shouldn’t be used as a replacement for compost or soil improver when preparing soil for planting.

AWBS stocks bark chippings and mulch for a range of different projects. Melcourt Value Cover Mulch is an economical recycled bark suited to larger beds and borders, while Rolawn Landscaping Bark offers a more consistent mid-dark brown finish. Melcourt Pine Mini Chips are a finer option for topping pots and containers, and their Bark Nuggets provide a chunkier decorative finish for borders and other landscaped areas.

For more advice on choosing and applying bark, read our guide to using mulch and decorative ground coverings.

Bark mulch, decorative gravel or weed membrane?

Bark mulch is a good choice for planted beds and borders where you want a natural-looking surface that also helps protect the soil. However, there are other options if you want a different finish or something longer lasting.

Decorative gravel provides a harder-wearing, low-maintenance surface that won’t break down in the same way as biodegradable materials. It works particularly well for paths, seating areas, front gardens and other spaces where you want a more permanent decorative finish.

Weed control membrane can be laid beneath bark or gravel to provide an extra barrier against weeds, while keeping the material separate from the soil below. Used beneath decorative gravel, it will help to keep the stones cleaner by preventing them from mixing with the soil.

Which product should you choose for autumn garden jobs?

Autumn is ideal for tackling jobs that will better prepare your garden for winter and the following spring. What you use will depend on the area you’re working on and what it needs.

Improving tired beds and borders

If beds have been heavily planted over spring and summer, now’s the time to give the soil some attention. AWBS Multi-Purpose Peat Free Compost is suitable for refreshing established borders, while Rolawn Soil Improver is good for ground that is compacted or difficult to work.

Topping up beds and raised areas

Where beds have settled or need extra depth, you’ll need a product that adds volume rather than a soil conditioner alone. AWBS Blended Loam Topsoil suits everyday topping-up jobs, while AWBS Premium Soil is a good option for raised beds where plants will be grown directly in it. Both are available in 850kg bulk bags, with the option of half bulk bags for smaller jobs.

Preparing vegetable beds

Once this year’s crops have finished, you can start preparing vegetable beds for next season. AWBS Premium Soil can be used where beds need topping up, while Westland Gro-Sure Farmyard Manure can be dug into existing ground and left to settle in over winter.

Finishing beds and borders

For beds that don’t need additional soil, an autumn mulch can provide a fresh covering before winter. Rolawn Landscaping Bark gives planted areas a tidy, consistent appearance, while Melcourt Value Cover Mulch is perfect for larger areas where cost is also a consideration.

Lawn repairs and seeding

Bare patches, uneven areas and worn lawns need products designed specifically for grass, rather than those used in borders. AWBS stocks lawn seeding soil for establishing new grass and repairing patches, as well as lawn top dressing for improving and levelling the surface of an existing lawn. You’ll also find turf and grass seed for larger repairs or areas that need starting again. For step-by-step seasonal advice, see our dedicated autumn lawn care guide.

Bulk bags or smaller bags?

The right bag size will depend on the scale of your project. Bulk bags are useful for filling beds, replenishing several borders or preparing larger planting areas. For containers, smaller borders and occasional topping up, individual bags may be easier to work with.

All of our own-brand soils are available in approximately 850kg bulk bags. Additionally, our Blended Loam Topsoil, Planting Soil and Premium Soil also comes in half bulk bags, so you can order a quantity that best suits the job. Whichever size you need, AWBS offers free local delivery with no minimum order value.

Autumn offers on soil, manure and bark

Planning a few autumn garden jobs? You can currently save on a number of soil improvement and mulch products at AWBS. Get more for your money by picking up three 50L bags of Westland Gro-Sure Farmyard Manure for the price of two. Or buy a bulk bag of selected Rolawn soil or bark chippings and get a second bag of the same product half price – perfect for reducing the cost of a larger landscaping job.

Collect your items from our nearest branch or we deliver products free of charge within 25 miles of our Oxford, Yarnton and Swindon branches. The choice is yours!

Final advice: choosing the right product

If you’re still unsure what to choose, start with the job you need it to do. When it comes to compost vs topsoil, topsoil is best for adding volume, filling beds or raising levels, while compost works to enrich garden soil before planting.

Soil improver, manure and mushroom compost can also help condition existing soil, depending on what it needs. For covering beds and borders, bark mulch provides a protective surface, while lawn repairs are best tackled with products designed specifically for grass.

Explore our full range of topsoil, compost and soil improvers alongside bark chippings and mulch, online or in-store at AWBS Oxford, Yarnton and Swindon. Whether you’re working on a few containers or a more substantial garden project, our team can help you choose the right product and work out how much you need.

We can also deliver your chosen products free of charge to eligible local postcodes. Enter your postcode into our free online delivery checker to find out if your address qualifies.