How to Beat Perennial Weeds Using Mulch

There is nothing more discouraging than fighting a losing battle. I suspect that one of the main reasons new gardeners give up on their dream of growing their own fruits and vegetables is the seemingly endless onslaught of perennial weeds that simply refuse to back down!

Perennial weeds are those persistent blighters that regrow each year, as opposed to annual weeds which germinate, grow, flower and set seed within a single year. Annual weeds are weaklings that can be dispatched with a sharp hoe – but perennial weeds are much more resilient.

Dousing weeds with weedkiller is not an option for organic gardeners, and indeed is not usually practical when they start growing up through your fruits or vegetables. That leaves us with a couple of options.

The Hard Option: Digging Out Perennial Weeds

If you’re feeling fit and keen, and want to completely clear your garden of weeds in one go, you can (try to) dig out every last scrap of weed root by hand. This is particularly difficult with weeds such as ground elder and buttercup, which spread by rhizomes that snap easily as you try to pull them out, regrowing from the tiniest scrap of root left behind in the soil.

Don’t, whatever you do, use a rotavator in an effort to clear the ground more quickly – the blades will chop the weeds up into tiny pieces, so if you had 50 weeds before, you’ll now have hundreds, if not thousands!

Hand-digging weeds takes a long time and even small areas can be very hard work. If you have a large area to deal with, don’t have time for such an intensive process, or would prefer not to give yourself chronic backache, there is another option.

The Easy Option: Organic Mulches

Mulching is an excellent method of perennial weed control. It provides a barrier that keeps weeds well below the surface, where most will eventually die due to lack of sunlight. Mulches work particularly well around perennial crops such as fruit trees and bushes, but can be used with annual crops too. It’s not an instant solution, but it will help you to keep on top of weeds and does away with regular epic weeding sessions.

Landscape fabric can be used but is not, in my experience, a great idea. It’s a quick fix, but eventually it will need attention. The fabric will degrade and break up over time, allowing weeds through. Removing weeds that have their roots tangled up in landscape fabric is, quite frankly, a pain in the bum.

Organic mulches, on the other hand, are wonderful because they not only suppress weeds but help to build better soil over time. This gives them a clear advantage, not only over landscape fabric, but over digging out weeds too.

The first thing you need to do is put down a weed barrier. Newspaper or thick cardboard makes a fantastic permeable, completely biodegradable, soil-enhancing alternative to landscape fabric. Lay newspaper five or six sheets thick (thick cardboard can be laid one sheet thick) and overlap them generously to avoid gaps that weeds could push up through. Soak it all well, then cover with at least two or three inches (5-8cm) of loose, well-rotted organic mulch.

Well-rotted garden compost, manure, sawdust, shredded bark, leafmould, coir, or a mixture of organic materials, all work well as mulch.

Maintaining a Weed-Suppressing Mulch

It’s important to replenish organic mulches as they rot down. This does make them more work than landscape fabric, but you will be rewarded with rich, friable soil. Grass clippings or straw can also be used to top up your mulch. Add another inch or two of organic matter every couple of months, or more often if you like. For instance, once or twice a month I will spread grass clippings from mowing the lawn onto my fruit and vegetable beds.

I won’t lie – occasionally a weed does force its way through. But not many! And any weeds that do make it through can simply be yanked out by hand. Don’t worry too much about getting every last scrap of root, as you’ll continue to mulch and keep weeds below the surface. Tearing off the top growth means the plant can’t photosynthesise, so each time you do this, the plant weakens. You’ll probably find that annual weeds germinate in the top layer of mulch, but a quick scruffle over with a hoe every week or two will see these off.

To begin with, avoid using tools to lever any weeds out of the soil, as you will risk puncturing the newspaper layer. In the second year you can start using a tool to help remove any really persistent weeds if you wish. A dandelion weeder, incidentally, does a stellar job of uprooting just about any weed I’ve encountered; its twin prongs get right under the crown of the weed and make it easy to lever it out with minimal soil disturbance.

If you’ve got any tips for (or questions about) keeping on top of perennial weeds, drop us a comment below.