Love you so mulch! Valentine’s Day puts Monty Don in the mood for mulching

– and he says it’s the best gift you can give your garden

  • Monty Don revealed mulching is the best thing to in UK gardens at the moment

  • British gardening expert explained the three functions a mulch should fulfill 

  • He also answered selection of questions from readers of Weekend magazine

What with it being Valentine’s weekend and my wife’s birthday, now seems the perfect moment to extol the virtues of my second favourite word in the English language: mulch.

Well, OK, I admit that it does lack a little in romanticism.

However, I would say that mulching is probably the single most helpful thing anyone can do in their garden and now, over the next few weeks, is the perfect time to do it.

Mulch is a layer of organic material spread over bare ground in borders and vegetable beds. It is not dug or worked into the soil but is left as a blanket.

To be effective it should be thick and dense enough to block light and to slow down evaporation.

In my experience this means a layer at least 5cm and ideally 10cm deep.

British gardening expert Monty Don (pictured mulching his borders), shared advice for mulching gardens over the next few weeks

A mulch has three distinct functions. The first is to suppress weeds. It does this by denying weed seedlings light.

Some, like groundsel or shepherd’s purse, that need light to trigger germination will simply not grow and others might germinate but the seedlings will not have enough light to survive.

Perennial weeds such as nettles or couch grass will be dramatically weakened and those that do make it through the mulch are much easier to pull out.

The second function is to retain ground moisture.

The majority of feeding roots are near the surface but this is the part of the soil that dries out the quickest in hot, dry weather.

As a response the plant will push its roots even closer to the surface to get what moisture it can, but if the drought persists they’ll dry out even faster.

Mulching breaks this cycle. The mulch may dry out but the soil beneath it remains moist.

Finally, a mulch of organic material will be worked into the soil by earthworms, moles and other burrowing creatures and improve the soil structure as effectively as digging.

So what is the best mulch? Whatever you have available is better than nothing.

But I have found that three, often used in rotation around the garden, work best for me on my clay soil.

The first is home-made garden compost.

In one sense this is the perfect mulch because it not only recycles garden waste and is free but it also reinjects your own specific soil bacteria back into the ground.

But no garden can ever make enough compost to mulch everything. My response to that is to keep my home-made compost for vegetables and potting.

I shred our woody waste – mostly from winter pruning – and use that around trees, shrubs and hedges.

I also buy pine-bark chips which I use to mulch the grass borders every other year as it is slightly ericaceous (acidic) and low in nutrients, and grasses like that.

Bark is an excellent weed suppressor and retains moisture but is slow to break down into the soil.

Finally there is mushroom compost, and I use this most of all. Mushroom compost is made from cattle manure mixed with lime, which helps break it down very fast.

Mushrooms are grown in this but once it is exhausted a fresh mix is needed and growers are happy to get rid of the old one for mulch. It is clean, easy to handle, does not smell and is very effective in every respect.

I have used hundreds of tons of it over the years and my soil is a delight as a result.

Its only major drawback is that it is alkaline so not suitable for ericaceous plants like rhododendrons, camellias, blueberries or raspberries.

But whatever you use, ladle it on generously – better to do half the garden properly than spread it too thin – and let it do the work for you.

And what’s my favourite word? Tilth, meaning soil that’s ready for growing healthy crops.


STINKING HELLEBORE (Helleborus foetidus) Monty chose stinking hellebore (pictured) as this week's plant, revealing that it thrives best in good drainage and fairly deep soil

This native plant is found at woodland edges so prefers light or dappled shade, and while it likes good drainage is much happier if it has some moisture and fairly deep soil.

The leaves give off an unpleasant odour when crushed, but the attractive flowers are carried on tall stems that can reach a metre in height.

The flowers vary from apple green to pale yellow, but all have a rim of deep red as if they’ve been dipped in blood.

Although short-lived, they’ll seed themselves freely and pop up in all sorts of crannies.


Late-flowering clematis such as C. viticella and C. ‘Jackmanii’ produce their buds on new shoots, meaning none of last year’s remaining stems will carry flowers and should be removed now.

Cut down to the lowest emerging bud and mulch thickly.

This article was first published on


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