How to keep weeds down without wrecking your soil

Stop the weeds arriving instead of pulling them out

Hand weeding is the most satisfying job in the garden and it is also the least efficient one, because every weed you pull is one that already germinated, grew and spent a fortnight taking water off something you actually planted. Nearly everything worth doing about weeds happens before they come up, and most of it comes down to covering bare soil, which is the one thing a weed seed cannot get around.

Mulch, and the depth that actually matters

A thin scatter of mulch looks tidy and does very little, because weed seeds will germinate straight through 20mm of anything. You want 50mm to 75mm of coarse organic mulch, which is deep enough to keep light off the seed and to hold moisture in the top of the soil, and it needs pulling back a few centimetres from the stems of your plants so nothing sits wet against the bark. Sugar cane, pea straw and lucerne all break down into the soil as they go, so the bed gets better every time you top it up.

Cover the bare bits with something living

Bare soil in a garden bed is an invitation, so where you have gaps between shrubs it is worth putting in a low ground cover and letting it do the shading for you. Creeping thyme handles our dry summers once it is established, and native ground covers will cope with a hot western aspect better than most things you can buy. Over winter, a bare veggie patch is better off under a crop of broad beans or peas that you slash and dig in before they set pods, which feeds the bed nitrogen and keeps the weeds out at the same time.

Soursob is a different problem

Soursob is the one that makes people give up, and it needs its own plan, because it grows from small bulbs sitting under the surface and mulch will not stop it coming up through. Digging it is the worst thing you can do, since the bulb sits on a cluster of tiny bulbils that break off and scatter, so one satisfying afternoon with a fork turns into five years of it. What does work is knocking the tops off every couple of weeks through winter before the leaves get big enough to feed the bulb, and the bulb eventually runs out of stored energy and gives up. It takes two or three seasons and there is no shortcut, which is the honest answer rather than the one anybody wants.

Use the hoe properly and it does most of the work

A sharp Dutch hoe skimmed just under the surface slices seedlings off at the root without turning the soil over, which matters because every time you turn soil you bring another layer of seed up into the light. Do it on a dry morning with a bit of sun forecast, so the seedlings dry out where they lie instead of rooting back in, and do it when the weeds are small enough that you feel a bit silly bothering. Hand weeding is for the ones you missed and for pulling out of a crowded bed, and it comes out far easier the day after rain.

Paths and paving

Boiling water poured straight from the kettle will wilt weeds in paving cracks within a few hours and it costs nothing, so it is worth doing on a small patch before you reach for anything else. Keep it off garden beds, because it kills whatever it touches including the surface roots of the plant next door. For a long driveway or a big paved area that is not really practical, and a path weeder does the job with less carting of kettles around.

The part people skip

Whatever method you pick, the weeds you get on top of are the ones you never let seed, so ten minutes a week in the same beds beats a whole Saturday every couple of months. Catch caltrop before it sets those spiky burrs in summer and you will not be picking them out of the dog for the next two years, which is reason enough on its own.

Shop related products

• Martins Organic Sugar Cane Bale 11kg. Coarse mulch that breaks down into the bed.
• Neutrog Whoflungdung Mulch 20kg. A heavier mulch that feeds the soil as it goes.
• Brunnings Path Weeder Concentrate 1L. For driveways and paving, not garden beds.
• Naturally Good Cow Manure 25L. For building up a bed so your plants outgrow the weeds.

Did you know we also stock Dutch hoes and swan neck hoes, hand weeders, a stand-up steel weeder that saves your back, weed mat and pins, and pea straw and lucerne bales in the garden centre, and a lot of the tools are not on the website, so give us a ring on (08) 8536 4333 to check what is on the shelf.

More from the garden centre

The mulch and the tools all come out of the garden centre, and if you bring in a photo or a weed in a bag we will have a decent go at telling you what it is.

Keep reading

• What is the cardboard weed barrier method?
• Soil amendments, and which one your garden actually needs
• Compacted soil, what it does and how to fix it

The soursob wins at my place every winter, and I'm at peace with that.

Candeece