I Tested Doff on Weeds and Grass

This is what happened

Tested by Daniel Woodley. Fact Checked by Hannah Miller. Published to Products on the 25th October 2022. Updated: 27th February 2023.

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Daniel Woodley

Daniel: Owner and product tester at DIY Gardening

Hello,

I’ve previously described Doff’s weed killer as the nuclear option, and for good reason.

But what’s in the bottle? How does it work? How long does it take to get rid of weeds? Does it kill grass?

Before you buy this weed killer from Doff, please read my honest review and look at the test results.

On this page, you’ll find:

  • My comparison between the concentrated versions of Doff and their “ready to use” products.
  • Test results including before-and-after photos.
  • Frequently asked questions answered.
  • Alternative weed killers.

Doff Products

Did you know that there are two versions of Doff Weed Killer?

The first is their “ready to use” product and the other is a concentrated version that many professionals use.

Both are currently on sale on Amazon:

DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
DOFF DOFFZA00 Weed Killers
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
Doff 1L Knockdown Systemic Weed Killer

Doff Ready-to-Use Weed Killer

Doff’s popular “ready-to-use” product contains 800ml of diluted product that you spray directly onto the weeds via the built-in trigger and sprayer.

This version is best used for spot-treating weeds, rather than treating large areas.

This product treats 30 square metres and costs £5.50 per litre.

That’s 18p per square metre.

Let’s compare that to the concentrated product:

The Concentrated Version

The concentrated version of Doff costs about £10.50, but some retailers are selling it for slightly less.

You get 1 litre of super contracted chemical.

Once diluted with water at the recommended rate, the manufacturer claims you’ll get 400 litres of usable product.

I always prefer to mix it slightly stronger so I think you’ll get around 300 litres.

At £10.50 per bottle, that works out at just over 3.5p per square metre.

A Quick Comparison

So there you have it – the ready-to-use Doff weed killer costs 18p per square metre while the concentrated version costs 3.5p per square metre.

I know that ready-to-use products are great for spot treatments and tiny gardens but given the long shelf life of these chemicals, I think you’re better off buying the concentrated version.

You will need to own a separate garden sprayer or watering can for the concentrated chemical as you shouldn’t contaminate anything you use to water plants. You will also need to dilute it yourself.

Doff bottle of weed killer

Doff Weed Killer Test Results

Here are the photos I took during my test of Doff weed killer.

The first was taken before the application and the others on day 7, 14 and 21.

I think these photos speak for themselves:

Test 1 – Weed & Grass

Doof weed killer test results 1

Test 2 – Weeds

Doff weed killer test results 2

Test 3 – Weeds

Doff weed killer test results 3
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
DOFF DOFFZA00 Weed Killers
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
Doff 1L Knockdown Systemic Weed Killer

As you can see from these images, well over a week passed before there was any change in the appearance of the weeds and grass.

In fact, in test 2, there wasn’t a noticeable difference until day 14.

By 21, both weeds and grass were well and truly dead.

How I Tested Doff

I tested Doff by diluting the chemical with water as per the manufacturer’s instructions.

I then waited for a calm, overcast day when rain wasn’t forecast for the next 24 hours.

Rather than using a watering can which is wasteful, I applied the product to the leaves of weeds and grass via a sprayer. For accuracy, I measured the test area and protected nearby grass and plants.

I then took photographs of the weeds and grass over the next few weeks.

If any weeds or grass grow back, I will update this page, but I don’t expect them to.

The test period started on the 29th of September 2022, when the weeds were still growing.

Effect on Nearby Plants/Grass

I measured the test area very carefully and by day 21 not only were the weeds and grass dead but also anything within 15cm from the edge of the test area.

Based on my test, I believe that Doff will kill any organic growth in the treatment area and outside of it by up to 15cm.

You may wish to consider this if you plan on using Doff near plants.

How Long Does Doff Take to Kill Weeds?

Doff’s ingredient is a systemic weed killer and not a contact weed killer.

Systemic weed killers travel slowly through the vascular system of the plant, through foliage, stems and into the roots.

I know from experience that this type of weed killer doesn’t have a quick “knockdown” effect.

Doff’s product stops the weeds from breaking down protein, and after several days, sometimes weeks, the weeds will start to discolour and die.

Most weeds will start to struggle after around 10-14 days and should look dead after around 21 days.

I know from past experience that if Doff is applied in the winter, it may take up to 28 days due to the dormancy or low growth rate of the weed.

The speed will depend on the type of weed and how fast it’s growing and its ability to transport the systemic weed killer to the cells.

The Fastest Acting Weed Killer Isn’t Always The Best

An alternative to systemic weed killers is contact weed killers.

These have a near-instant “knockdown” effect but often fail to kill off the root system.

If the foliage is finished off too quickly, it can’t transport the chemical into the roots.

Products such as vinegar, boiling water and weed burners are examples of contact weed killers that produce instant results.

There are several acids that produce a similar effect and can often be found in popular organic weed killers.

Through years of testing and usage, I’ve found that none of these will be as effective as Doff in the long term – if the foliage is burned off too quickly, there’s nothing left to transport the chemical to the roots.

Doff Works on These Weeds and Plants

Doff will kill all known soft-stemmed plants, including grass, weeds and shrubs.

The main chemical in Doff is also effective against hard-stemmed plants such as bamboo, brambles and the notorious Japanese Knotweed although I’ve found that repeat applications or a stronger dose are required.

Residual Activity: When Can the Area be Planted?

The key ingredient on Doff breaks down in the soil in days and weeks, it doesn’t take months.

It also binds well and isn’t easily transported to nearby plants – in my test, only plant life within 15cm of the test area was affected.

In most cases, new plants can be grown when the treated weeds have died away; this will usually be after 7-21 days.

A Stronger Alternative Weed Killer

Doff will treat all known weeds and many other plants (albeit slowly), but you may need something stronger to treat:

  • Brambles.
  • Japanese knotweed.
  • Running Bamboo.
  • Tree Stumps and Roots.

A stronger alternative to Doff is Gallup which contains the same ingredient but at 3 times the strength.

I believe that for most situations and regular garden weeds, Doff is the best option but Gallup will treat tree stumps and woody plants.

Buy Gallup on Amazon.

An Alternative Weed Killer For Lawns

As you saw from my test results, Doff’s weed killer also kills grass.

If you’re looking for a strong lawn weed killer, consider Weedol, which I tested here.

Weedol is available on Amazon.

An Analysis of Online Reviews

Online reviews and ratings can be problematic as consumers often rush to write a negative review, sometimes before giving the product enough time to work.

As Doff requires 7-21 days to see results and up to 28 days in colder temperatures, there are a few complaints and negative comments, including from those who waited no more than a few days.

Despite the few complaints, most of the reviews I saw were positive with plenty of people praising the end result but noting that it took a while to work.

I looked at hundreds of reviews online.

Here’s what I found:

  • 86% of reviewers rated Doff 4-5 stars.
  • 6% rated it 1 or 2 stars out of 5.
  • Those that rated it low often didn’t wait more than a week.
  • A few commented that the packaging broke in transport.

FAQs

Below I’ll answer the most common questions about Doff:

Why Should I Trust Your Advice?

I’ve used Doff successfully dozens of times but don’t take my word for it, check out the before and after photos I’ve published on this page.

Also, there are hundreds of reviews on Amazon you can explore.

Will Doff Kill Grass?

Yes, it will completely kill grass and roots.

Can Doff Be Used on Weeds Growing on Hard Surfaces?

Doff can be used on hard surfaces but treat a small test area first.

Is Doff Safe to Use in Gardens That Pets and Children Use?

Children and pets should be kept off the grass until the product has dried or 24 hours have passed.

Care should be taken that the wet product isn’t transferred to lawns, carpets etc.

Does Doff Kill the Roots?

Yes but a repeat application or a stronger mix should be used on brambles, ivy, and woody plants.

What Chemicals are in Doff?

The concentrated version of Doff contains:

90 grams per litre of glyphosate

What's Doff's Coverage Rate?

The 1 litre ready-to-use Doff product will treat 30 square metres.

The 1 litre concentrate version will treat 300-400 square metres once diluted.

What's the Best Delivery Method?

Watering cans are wasteful but sprayers can cause mist drift and on windy days may contaminate surrounding areas.

I recommend a small 5-litre sprayer be used on a calm, windless day.

Is Doff Weed Killer Safe?

Doff contains glyphosate and there has been much discussion about safety over many years.

As with most garden chemicals that are only used occasionally and only as described by the instructions on the bottle, there is little to no risk to humans.

There may be an elevated risk to those who use this chemical on a daily basis but that is currently unproven.

Further reading:

EPA (USA) position on glyphosate

EFSA (EU) statement

 

DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
DOFF DOFFZA00 Weed Killers
DOFF DOFFZA00 Weed Killers
Doff 1L Knockdown Systemic Weed Killer
Doff 1L Knockdown Systemic Weed Killer

Author: Daniel Woodley

Daniel has over 18 years of experience in the construction, home improvement, and landscape garden industries.

He previously worked as a project manager and has experience in managing teams of tradespeople and landscape gardeners on both small and medium sized projects.

Daniel is also a keen gardener and enjoys growing unusual plants and tending to his lawn.

More About Daniel Woodley.

Daniel Woodley

Why Trust Us? Our Experience & Testing

Daniel has previous experience with Doff and products with similar chemicals in them.

As Doff is a popular weed killer in the UK, he tested this product between September and October 2022 on three different weeds and took before, during and after photos as evidence.

The alternative products were suggested based on past use, their chemical composition and concentration.

This review was published by Daniel Woodley. Claims and important statements were fact-checked by Hannah Miller prior to publication.

Learn more about DIY Gardening’s review and testing process here.

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This review of Doff weed killer was first published here at DIY Gardening

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