Mulching guide: what are the benefits and when should you do it?

This article has the professional seal of approval from Paul Griffin, owner of Paul's Garden Services and Handyman in West Yorkshire, UK. Paul is an experienced landscaping professional who has spent decades building his lawn maintenance expertise – to see his skills in action, you can follow Paul’s work here.

Most professional landscapers will incorporate mulching into their garden and lawn care routine. It’s a great tool to have in your repertoire; it’s a straightforward process, there’s no learning curve, and the benefits can be numerous.

By learning more about mulching, from the different types you can use to the best time of year to do it, you can make easy wins for your lawns and gardens, giving your clients assurance that you’re giving their much-loved spaces the nourishment and protection they need.

Mulching isn’t part of a daily routine, but it should definitely feature on your annual list of to-dos. So, whether you need a refresher or you’re new to landscaping and gardening, this guide will provide you with the tips and tricks you need to be a mulching pro.

What is mulching?

It’s the practice of applying a layer of material called mulch to the soil surface or grass. Mulch can either be applied directly on top of bare soil or the lawn, or it can be used to cover compost in containers or other growing boxes.

So, that’s the process – but what is mulch itself? Mulch is a broad term for a layer of organic or inorganic material, often in the form of clippings, bark, wood chips, or leaves, that’s used by gardeners and landscapers because of its myriad of benefits and, on plant or vegetable beds, its appealing, clean look.

As such, it’s a material we strongly recommend you consider for your client’s garden and landscaping projects.

Mulching and lawn health

Mulching is an effective way to improve your client’s lawn health with minimal effort on your part. A mulching mower will finely shred grass clippings and spread them across the lawn, saving you from having to empty a collection box while simultaneously benefiting the grass.

To learn more about the benefits and potential risks of mulching for a lawn, read our quick breakdown below.

What are the benefits of using mulch for lawns?

• Less watering required so saves water.
• Suppresses weeds and can deter pests.
• Provides nutrients to nourish lawn.
• Insulates the lawn to provide protection.
• Saves time disposing of grass cuttings.
• Can improve soil structure and fertility.

Providing nutrients for the lawn is perhaps the most important benefit mulching offers. It can contribute almost half a kilogram of nitrogen to a lawn – most require just under two kilograms of nitrogen per year to thrive – saving you time and money on a fertiliser application.

It also shields the lawn from strong sunlight, acting as a protective barrier from extreme temperatures and preventing weeds from thriving. Some sunlight penetrates through the layer of mulch to keep the lawn healthy, but not enough to cause damage when temperatures rise.

Mulching will also help with moisture retention by limiting the amount of evaporation occurring at the soil surface, giving the grass extra water and providing protection from drought. This not only saves resources, since less watering is required, but it can also improve the overall growth potential of the grass. Once the mulch layer is broken down by invertebrates such as worms, you’ll also see improvements to the soil’s structure, its ability to conserve moisture, and its fertility, ultimately benefiting the grass.

Potential risks of mulching for lawns

Mulching is overwhelmingly beneficial to lawns, but if due care is not taken, it can prove damaging. These are the potential risks and considerations any professional will – or should be – aware of.

• Spread of weeds and disease – if your lawn clippings contain grass blighted by disease or are infested with weeds, mulching can lead to more weed growth, spreading them across the lawn.
• Could create environment for fungal disease. The protective layer of mulch retains moisture and heat, with very limited air flow. If disease is present, this environment can allow them to thrive.
• Too much mulch can smother the grass. Avoid depriving the grass of oxygen by spreading the grass in an even and thin layer, breaking up any clumps.
• May increase thatch build-up. Mulching doesn’t cause thatch build-up, but if the lawn has an existing thatch issue it will exacerbate it.
• Mulch before mid-autumn. If you mulch shortly before very cold weather, you may hinder the lawn’s ability to hibernate and protect itself from frost.
• Avoid mulching long grass. A mulching mower won’t be able to cut the grass clippings as finely, so clumping will occur.
• Unlikely to benefit chemically treated lawns. If a lawn is treated with pesticides and herbicides, there will be a lack of microbial activity in the soil that may limit its ability to break down the grass clippings.

What are the different types of mulch for lawns and planting?

Broadly, mulch can be categorised as organic and inorganic; that is, either it can be broken down and decomposed by bacteria, fungi, and microorganisms or it can’t be decomposed – meaning it can exist indefinitely in the environment. Let’s take a look at some of the main types of mulch, their advantages, and their disadvantages.

Types of organic and biodegradable mulches

Organic and biodegradable mulches offer an excellent, environmentally friendly way to improve your clients’ lawn or garden.

For lawns, you would use grass clippings or leaf mulch. For borders and planting, there are a few other organic options: some of these mulches contain natural or added slow-release nutrients to improve soil quality.

Grass clippings or leaf mulch

As they decompose quickly, grass clippings and leaves can be a great way to add nutrients to the soil and suppress weeds. But it's important to avoid grass that’s been treated with herbicides or pesticides, since these can be toxic.

As discussed, grass clippings from using a mulching mower provide several benefits that can improve lawn health.

Garden compost

Do your clients know they can make their own mulch with a compost bin? Garden waste is an accessible and affordable mixture that can be used as mulch – just make sure to tell your clients to apply the compost as a layer on top of the soil, rather than mixing it in (if they would rather do so themselves).

Though a very good all-rounder, garden compost is especially good when it comes to retaining moisture. If you make your clients aware of the benefits, they may provide a compost bin for you to use.

Wood or bark chippings

Popular among gardeners and landscapers for its strong drainage qualities, wood chips are easy to apply and create an attractive, ordered look to beds, borders, and pathways.

It’s worth calling your local tree care surgeon, since they may be able to pass on their wood chips or chipped bark for a relatively small fee.

Straw or hay

Straw is particularly useful because it decomposes at a much slower rate than grass and leaves. It also provides a more attractive finish, nicely contrasting with leafy shrubs. More importantly, straw and hay mulch can act as a habitat for spiders and other insects that will eat pests, providing long-term gains for your customers.

What are some advantages and disadvantages of using organic and biodegradable mulches?

Organic and biodegradable mulch – particularly one made from lawn clippings or fallen leaves – is the most practical, effective, and environmentally friendly option for improving lawn health.

For borders and planting, you can make organic mulch yourself with waste organic matter from other jobs and you only need a compost bin or plastic bag, making it a cheap, accessible, and sustainable form of mulching.

One of the main advantages of organic mulch is that, because it’s biodegradable, it will break down relatively quickly and won’t harm the environment; however, as organic matter degrades it can release harmful greenhouse gases, such as methane and carbon dioxide, as well as ammonia.

Types of inorganic and non-biodegradable mulches

Inorganic and non-biodegradable mulches can be a useful option for plant and flower beds, as well as borders.

Gravel

Using rock and gravel is a quick and easy way to suppress weeds and retain moisture. But because they heat up in direct sunlight, they can make soil temperatures too hot to sustain plant life, so always use with caution.

Plastic or fabric sheeting

Like gravel, a synthetic material like plastic or fabric is a great way to suppress weeds with little effort. Sheeting performance varies, so it’s worth doing your own research, particularly when it comes to infrared transmitting (IRT) plastic sheeting as these typically cost more.

It’s also worth pointing out that most plastic sheeting and landscape fabric will need replacing as many types disintegrate over time.

Recycled rubber chips

A more sustainable option is using rubber chippings from old tyres. By repurposing waste material instead of buying a virgin or synthetic mulch, you’re limiting your carbon footprint.

Rubber also breaks down naturally. However, it could contain harmful chemicals from the road, so do your research and make an informed decision that works for you and your clients.

What are some advantages and disadvantages of using inorganic and non-biodegradable mulches?

Inorganic mulches are quick and easy. It’s less hassle and time-consuming, for instance, to purchase a bag of gravel than growing your own composted leaf mould, which typically takes between 6 to 12 months. They’re also attractive, with gravel in particular offering a clean and ordered look, and provide excellent weed suppression.

This type of mulch is effective because its opacity blocks sunlight from entering the soil below. Without sunlight, photosynthesis can’t occur, meaning weed seeds won’t germinate and grow, while any existing weeds will die. As an added barrier of protection, it also protects crops and plant roots from frost, drying winds, and too much direct sunlight.

However, unlike their biodegradable counterparts, inorganic mulches don’t break down. This is a bigger problem in the case of plastic, landscape fabric, and other synthetic materials because they can pollute the environment, leaching toxic or harmful chemicals into the soil and local waterways over time. Therefore, it's always worth considering natural materials like rocks and gravel first.

It’s important to note that an inorganic mulch won't contribute nutrients to the soil so could stunt potential plant growth. Moreover, any beneficial effects will be nullified if they prevent desirable plant roots from accessing water, air, and other nutrients.

When should I apply mulch?

The ideal time to apply mulch to lawns is during spring, particularly in the months of May and June, and in the summer. As the grass is growing rapidly during these periods, it will more readily absorb the nutrients provided by, say, recycled grass clippings. During this period, you can mulch once or twice a week.

Early to mid-autumn is also a good time to mulch, as plants are dying back and leaves, a natural mulch, are falling – giving you a great opportunity to reap the benefits of mulching. Though, as you can only mulch when the grass and leaves are dry, your opportunities to mulch in autumn are likely few and far between.

For borders and areas for planting, late spring is ideal, as weeds won’t have germinated yet. This means you'll be able to get in early, perhaps while spring planting, and prevent weeds before they begin to grow during the summer.

How to apply mulch to lawns – our top tips for success

1. Check soil moisture levels; if it's sodden or waterlogged, then delay applying mulch.
2. Examine the lawn for signs of disease and remove larger, perennial weeds before mulching.
3. You should mulch regularly in spring and summer to make the process most effective. Take care not to cut long grass which will clump; keep it evenly spread across the lawn.

Share the results of your efforts with us

By following our guide to mulching, you can make noticeable improvements to gardens and green spaces by suppressing weeds, nourishing the soil, protecting plants, and optimising conditions for growth – all without adding too much additional work or material costs.

That’s why regular mulching should be in every landscaper’s annual maintenance schedule. And with our guide, there’s now no reason why it can’t be in yours.

Had success with mulching thanks to our guide? Share the results of your handiwork with us on social media!