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What to put down to stop weeds coming through. Weed membrane and mulch pictured as alternatives to herbicides and no treatment.

What do you put down to stop weeds coming through?

Weeds are something every keen gardener or landscaper battles at some stage. There are several solutions to consider, whether your aim is combatting or preventing weeds. Herbicide treatment (weed killer) provides an option, but isn’t a long-term method of managing weeds. Alternatives to herbicides include manual methods, such as hand-pulling, raking or hoeing. However, these can be quite physically intensive when covering a large area. So, what can do you put down to stop weeds coming through? A garden membrane (weed blocker fabric) offers a solution, if you understand how to stop weeds growing through membrane.

Using weed killers

Using weed killer is a popular choice for many. The simplicity of giving unwanted plants a squirt from a bottle and then waiting, can be tempting. Although, alternatives to herbicides are now more commonly encouraged. This alone should give pause to think about other methods. However, there is also a responsibility to consider. HSE (Health and Safety Executive) pesticide (includes weed killers/herbicides) guidance states:

If you use pesticides in your garden, allotment, or on houseplants you are legally responsible for using them correctly and effectively. You must keep your garden and allotment safe for people, pets and wildlife.

The effects of herbicides can go beyond the benefits highlighted on the label. Used incorrectly, weed killers can impact non-targeted plants, remain in the soil and polute water courses. When used safely and appropriatlely, herbicides play an important role in agriculture. They have also become an integral part of invasive weed control, for plants including Japanese knotweed and Himlayan balsam.

When pesticides are used as part of work, Official Controls (Plant Protection Products) Regulations 2020 must be complied with.  It is recommended that personal protective equipment is worn, even when using herbcides intended for home use.

When is the best time to put weed killer down?

There isn’t a single correct answer to this question. Weed killers (herbicides) incorporate one or more active substance with other materials. These combine to make each act for the intended purpose, or for the appropriate plant/s. Added to this, plants are not all the same when it comes to their physiology and metabolism.

Therefore, there isn't a one size fits all solution for the best time to put weed killer down. The answer is, ‘always read the label’. Whether you are experienced and a qualified sprayer, or applying a shop bought solution, this remains the same. And, if you’re unsure, it might be best to use an alternative method of weed management.

Can you plant after using weed killer?

This depends on the product that is being used, when it was applied, how much, and how often. This again highlights the importance of carefully reading the product label. The HSE provide guidance notes on Understanding the Product Label of pesticides. This helps when navigating the label for the required information. If you are still uncertain, a visit to the Pesticides FAQs page of the HSE website is highly recommended.

Alternatives to herbicides

Manual extraction, pulling out weeds by hand, raking or hoeing, is the main alternative used. This can be quite physically intensive on your back and knees. And, when employing this method, it is essential to pull up the whole root of the weed. In some cases, depending on the species, this can be quite a challenge.

Fortunately, there is an alternative doesn’t involve as much physical activity, or spraying any chemicals: installing a weed membrane. The first consideration, is that the range of available products is huge, and the quality varies enormously. We’ve put together some useful information to help you decide what kind of weed barrier is right for you.

Will weed blocker fabric work?

Weed blockers, or weed membranes, provide amongst the best alternatives to herbicides by removing the conditions needed by seeds to germinate. They do this whilst also stopping the growth of already active seedlings.

The quality of the weed blocker fabric will be crucial in determining how good it will be at preventing weed growth. There are different weed blocker fabric materials and construction methods to consider. Added to this, there are a variety of thicknesses. Each lends distinct characteristics and qualities to the product.

Weed blocker fabric

A weed blocker fabric that is thin and easily torn won't be effective, or last. Opting for a material that is tough, flexible, and engineered to block out the light emerging plants need is advisable. However, if a tough membrane is also impermeable (or waterproof), it will also starve the soil beneath of water. This will impact the health of the soil and the beneficial micro-organisms it holds. The sweet spot is one where the membrane is tough, flexible and porous. This allows the membrane to work as a weed blocker, as well as allowing water to drain through into the soil below.

How to stop weeds growing through membrane

Purchasing a good quality weed membrane is the simplest way to ensure that your garden project works as intended. It isn’t hard to find examples of membrane installations where plants have simply grown through the fabric. In these instances, people typically employ a product that is inexpensive and of low quality. Tough, capable weeds are able to penetrate the material, then other plants weaken it further.

Removal of these products after they fail can be an arduous, time-consuming process. To stop weeds growing through membrane, you really need to invest in a suitable weed barrier. Installing a good quality membrane is often more straightforward than with the cheaper varieties and, most importantly, the level of weed suppression will be far higher and last much longer. Removal of a good quality weed barrier will also be more straightforward, it will come away easily, with less plant matter attached.

Testing Root Barrier Store's weed blocker fabric

We conducted tests on our WeedSecure Pro Weed Barrier and demonstarted how, when installed correctly, it completely stops  weed growth.

Sprinkling seeds in product test

After preparing the ground by raking out large stones and leveling the soil, we cut the WeedSecure to size and laid it edge to edge in the border. Over the top of the barrier, we placed a mulch layer of bark chip which helped the aesthetics of the border.

Applying a layer of bark on top of weed membrane

Because WeedSecure is a permeable non-woven geotextile, it ensures the vital flow of water and nutrients into the soil. The bark mulch on top not only enhanced the appearance and hindered weed growth, but also facilitated the passage of essential minerals and natural compounds into the soil below.

Test area - with and without WeedSecure Pro weed membrane
Several months after setting up the experiment, we returned to find that no growth had occurred where WeedSecure Pro had been laid. Beside it, where no membrane was in place, a healthy patch of weeds had emerged. 

We continue to monitor the site and will update this blog with our findings.

In addition to our weed membrane, the Japanese knotweed root barrier and bamboo barrier products we stock have also been installed and tested on-site by the Root Barrier Store team.