The truth about weed control: separating fact from fiction

Cut back the plant first to allow water into the crown of the plant. This method is often used on weeds growing in-between paving stones. It does kill the top of the plant but may not always reach the roots, especially with weeds that have long tap-roots, such as dandelions.

Expert’s opinion

"It's a very good method, but it uses a lot of energy, which is not good for the environment. What I use is waste water from cooking, so once I've drained my potatoes I rush out and use the water on my patio. Alternatively, for large areas you could find a landscape contractor with a steam foam machine. Steam foam uses less water and less heat," says Guy.

2. Vinegar

This is a natural herbicide and harms weeds because the acetic acid in vinegar damages the cell walls in weeds, meaning they lose moisture. When choosing a vinegar look for the one with the highest amount of acetic acid. It may kill the top of weeds, but it might not kill off the roots and it will also damage other plants if any of the vinegar gets sprayed onto them by accident. This works better on annual weeds than perennial weeds.

Expert’s opinion

"Vinegar is actually acetic acid, the same ingredient that's used in approved herbicides. Use it neat, as the stronger the better, but it only kills the seedlings of broad leaved weeds and won't have any effect on grass weeds. It could scorch other plants, so it's better to use it on the patio. Apply it on a sunny day. If it rains afterwards the efficacy will be much reduced. Pelargonic acid is slightly more effective than vinegar, and you'll find products made with this at the garden centre," says Guy.

3. Lemon juice

Lemon juice has citric acid in it, which makes weeds shrivel up as it dehydrates the plant cells. You can either juice lemons to make your own solution or buy a bottle of lemon juice from the supermarket. Fill up a spray bottle and spray the solution on to the weeds’ leaves.

Expert’s opinion

"Lemon juice is citric acid. There are no products offered that contain this. If it was effective you'd have thought there would be an approved product with citric acid in it. It is probably less effective than other organic acids," says Guy.

4. Weed guns

Known as weed guns or weed torches, these tools use heat or flames to kill weeds. The gas type uses flames, whereas the electric weed guns use heat. Both destroy plant tissues, and the weed dies. They are best used on annual weeds, as the heat will only kill the top of the plant, and not the root.

Expert’s opinion

"They are very effective against top growth. They are fine unless you're dealing with bindweed or ground elder. Soil is a good insulator, so the heat doesn't travel to the roots. Also, there's a fossil fuel cost in money and to the environment. Do it on a sunny day to save energy, and heat the weed instead of burning it. Come back another day for a second treatment, and it will burn much quicker. Be careful near vehicles because of petrol vapour."

5. Weed-suppressant membrane

These work by blocking light to stop weeds germinating. They are often used on vegetable patches before the growing season begins to prevent weeds from growing. They can also be used in gravel gardens below the gravel and are designed to let water move through. There are various types, including synthetic types and biodegradable types, such as those made of coconut fibres or hemp.

Expert’s opinion

"This is a great idea. Ideally use biodegradable types like cardboard, and then put grass clippings or wood chips on top to make it less slippery and increase the mulching effect. For short-term use, you could use paper mulch, especially on the veg patch. Use it around courgettes, for example, and by the time the courgettes are grown, the paper has rotted away," Guy says.

Tried and tested methods of weed control

There are some methods which have been proven to work. They are not all time-saving, but in the long run they will help prevent weeds returning. Here are a few ways to tackle weeds:

• Make a stale seed bed – "Make a seed bed, let weeds germinate and then hoe the weeds off. If you hoe them off in May, you can plant out, courgettes for example, in June," says Guy. This old technique should mean there's less competition from weeds through the growing season.
• Hand removal – either by pulling up annual weeds, hoeing or using a tool that helps to get out the roots, such as a weeding knife, for weeds between pavers, or a dandelion weeder for those with deep tap roots.
• Cut back weeds regularly – keep chopping the top of perennial weeds to ground level to weaken the weed. This is a good method if you can't get access to dig up every bit of root within a border.
• Cover weeds – lay cardboard or a membrane over the top. This is useful for vegetable patches (see above). As well as the plastic membrane, there are biodegradable types available such as those made from corn starch or jute. These come in a variety of thicknesses, with the thicker ones lasting for up to three years.
• Sow and plant densely – cover bare soil with crops or plants, using groundcover to fill in the gaps between shrubs and perennials

Living with weeds

Although there may be parts of the garden that you'd like to keep weed-free, such as your lawn or vegetable garden, tolerating some weeds can attract beneficial insects. Dandelions, as well as some lawn weeds such as clover and daisies, are a good source of nectar for bees.

"Weeds like red dead nettle are useful for bees and pollinators, so let them flower, but perhaps don't let them set seed," Guy says.