Peter Dowdall: Let's get down and dirty and hand-weed gardens 

Because good old-fashioned weeding by hand is more environmentally friendly than any weedkiller we can make or buy

Time to don the garden gloves. File pictures

Spring has sprung bringing promise — but also the dreaded weeds.

Traditionally many people used weedkillers to kill weeds in the garden and glyphosate is the active ingredient in the vast majority of weedkillers available for domestic use. But many studies have shown a possible link with cancer and several countries have banned the sale and use of weedkillers containing glyphosate.

If you visit the local garden centre or hardware store now you will see shelves of products all screaming about their “organic” and “glyphosate-free” status. There are also many homemade remedies and recipes but are they any good and more importantly, are they any safer?

Many of the glyphosate-free weedkillers have the active ingredient acetic acid, better known to you and me as vinegar which can effectively kill weeds by disrupting their cell membranes and drying them out. This is often considered a more environmentally friendly alternative to synthetic weedkillers.

You can use the vinegar that is on your kitchen shelf if you like, to kill weeds, but horticultural-grade vinegar has a stronger concentration of acetic acid, about four times that of what we put on our chips.

Spring gardening brings forth many beautiful blooms, but also brings weeds.

Vinegar acts as a “contact” weedkiller and it is not selective, meaning that it will kill what it comes into contact with, particularly if used on dry, sunny days. However, that won’t be any good for persistent, perennial weeds as these will simply regenerate from the root system below the ground.

While it can be an effective and environmentally friendly weedkiller, it's important to note that vinegar can alter the pH of the soil temporarily. While this effect is usually short-lived, it may impact soil chemistry and nutrient availability for a short period, so it's best to use it selectively and avoid excessive use in the same area.

Excess vinegar runoff can potentially enter waterways and affect aquatic ecosystems. While vinegar itself is biodegradable and breaks down relatively quickly, excessive amounts may disrupt the pH balance of water bodies and harm aquatic life.

We rely on the soil and the magic which happens within for our gardens to be healthy. Healthy soil is filled with a variety of organisms, including earthworms and beneficial microbes, that play important roles in soil health and fertility. While moderate use of vinegar is unlikely to have a significant impact on these organisms, high concentrations may be harmful to them.

A quick search online will lead you to homemade weedkiller recipes using baking soda. Baking soda also works by altering the pH level of the soil, in the opposite way to vinegar, it increases the alkalinity of the soil, making it difficult for weeds to survive.

Baking soda (sodium bicarbonate) is not harmful to the environment. It's a naturally occurring compound that is non-toxic and biodegradable; however, it may have indirect environmental impacts depending on how it's used.

Whilst increasing the alkalinity of the soil may kill weeds, it can also affect the surrounding soil and potentially harm other plants that prefer acidic soil conditions.

If excess baking soda is not absorbed into the soil, it can wash away with rainwater and enter waterways. While baking soda itself is not toxic, excessive amounts can disrupt the pH balance of aquatic environments, potentially affecting aquatic life.

Again, as with vinegar, baking soda may persist in the soil for some time after application, especially if applied in large quantities. This could affect soil microbial activity and nutrient availability, although the long-term effects are not well-studied.

Both vinegar and baking soda are regarded as safe for birds and other wild animals that may be in our gardens. They aren’t attracted to either and thus are unlikely to ingest any. However, if they did ingest treated weeds this could lead to gastro problems. If they come into contact with any treated areas, it may lead to irritation of the skin, feet or eyes but is not likely to cause long-term damage.

Meanwhile, salt and washing powder, both of which are often used to treat moss on hard surfaces such as paths and driveways, are both harmful to birds and wildlife.

The chemicals in washing detergents, such as surfactants and other additives, can be toxic to animals if ingested or if they come into contact with their skin or feathers.

There are other environmental concerns with using either as a treatment for moss, both can harm fish and other aquatic organisms.

Whilst salt and washing powder are effective at killing moss, the environmental cost is probably too great. Baking soda and vinegar, on the other hand, don’t have a significant environmental impact but their effectiveness is limited.

Time to don the gloves, arm yourself with a hand trowel and get down and dirty with some old-fashioned hand weeding, followed up by the best practice of all, mulching to a depth of 10cm.

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