Does frost kill weeds? Gardening experts reveal whether the cold is an effective enough weed killer

While you might not be too worried about weeds in your garden during winter, you may be wondering if the damaging effect of frost can help you lessen the labour come weeding time.

There's no easy way to get rid of weeds; unfortunately, they're pretty persistent and can grow at an alarming rate, often in the most frustrating of places. Other garden plants aren't usually as invasive or hardy, which is why we need to protect plants from frosts each year before the winter weather arrives.

You might be wondering then if frost has the same damaging effect on weeds as it can on your other, welcome plant life. To find out just how lethal the freezing temperatures can be, we asked plant experts to clarify.

Does frost kill weeds?

If you've been putting off sorting your garden out due to the cold temperatures, you may have noticed the weeds getting a little out of control. The weather may also have you hoping that Mother Nature can help you out and banish some of those weeds with a 'killing frost'. But can frost actually kill a weed, or is it just another winter gardening myth?

"Frost can both damage and destroy weeds, just like other plants in your garden," explains Lucie Bradley, gardening expert at Easy Garden Irrigation.

"When the temperature falls sufficiently for frost, the water within the cells of the weed can freeze. When this water freezes, it expands, and with nowhere to go, it breaks the cell walls. As these cells are vital for the life of the weeds, enabling them to grow and reproduce, when they are broken, this process stops, and the weed dies."

Lucie Bradley

With over 28 years working in the garden industry, Lucie has been fortunate enough to spend every day speaking to both amateur and professional gardeners. Encouraged to garden since she was old enough to walk, she believes that you can never know everything about gardening, as it is constantly evolving.

In the same way, there are the best drought-tolerant plants that survive through the summer, and there are some weeds that can take on the frost better than others.

"Some weeds are more susceptible to being killed by frost than others, with summer annuals like crabgrass and spurge being tender weeds that can't survive in cold temperatures, and they will not regrow in the following year," continues Lucie. "Whilst other common weeds, such as chickweed, meadowgrass, dandelions and nettles will not be killed by cold temperatures and frost, with the winter annuals continuing to grow and the perennial weeds reemerging the following spring."

"For this reason, frost should not be considered a method of killing weeds, especially as frost can stimulate the growth of hardy weeds like chickweed and henbit, and strong perennials like bindweed and dandelions have nutrient-storing root systems which use the winter period to be dormant but alive underground, ready to grow vigorously again in spring," she finishes.

What temperature is considered a killing frost?

If you've protected your plants from heavy rain and frost, you'll be more than aware of how damaging temperature drops can be to your garden. For frost to really pack a punch, the climate has to reach a certain temperature.

"If temperatures reach 0°C to -2°C (32–28°F), a light frost, this will damage tender growth, wilt leaves and cause only cosmetic damage," explains our w&h resident gardener, Orpheus Alexander.

"Once it drops to -3°C to -5°C (27–23°F) for several hours, this is when the frost will kill most annual weeds; it'll blacken foliage, but it still won't kill perennial roots. Only when a hard frost arrives, anything below -5°C (23°F), will this weaken some perennials and improve the effectiveness of follow-up weeding," he adds.

Orpheus Alexander

Orpheus is a gardener, designer and lifelong plant enthusiast with a hands-on approach to creating natural, welcoming spaces. He is passionate about working with nature to design gardens that feel alive, seasonal, and personal. He also shares practical tips and behind-the-scenes glimpses of his projects on social media, where you’ll often find him talking plants, design ideas, and the joys (and challenges) of real-life gardening.

FAQs

What is the best weather to kill weeds?

Aside from the wildlife-friendly weeds you shouldn't remove, knowing the best weather for killing weeds can be a huge help in their initial removal and ensure they stay away.

"The most effective time to tackle weeds is when they are actively growing,” starts Jane Fairlie, technical development manager at Pelsis Doff.

“This is usually during mild, dry conditions, as weedkillers can then move efficiently through the plant’s phloem and xylem systems, reaching the roots and giving longer-lasting control,” she adds.

Orpheur echoes this, adding that for manual removal, it's also helpful to wait for moist soil after rain, as this will help ensure the roots come out intact, which is crucial for removing perennial weeds.

Should you get rid of weeds before frost?

Don't make a common winter gardening mistake by waiting until the frost arrives to tackle your weeding. While the frost can help damage certain weeds, it'll make manual weed removal a real challenge.

"It’s important to continue to weed your garden all year round, although winter makes it harder to kill weeds as weed killers don't work effectively. Manually pulling weeds from the ground is still effective as long as you ensure you get the roots too," explains Lucie.

"If the roots are left in the ground, the soil can act as insulation during winter, with deep roots storing up energy so they are ready to start sprouting when the weather improves. This means it's good to keep weeding before frost, with damp soil actually making it easier to pull roots from the ground," she adds.

If you're thinking about waiting until after the frost thaws to manually weed, it will still be a struggle as the melted frost leaves sticky, muddy soil.

When it comes to your lawn, there are ways you can remove weeds without damaging the grass. It's best not to tackle this job while there's frost. Not only will you struggle to remove any weeds, but you can also damage the brittle, frozen grass blades by walking on it.