Spectracide vs Roundup – The Showdown

The Main difference between Spectracide and Roundup is that Roundup effectively eliminates the whole weed, including its roots, whereas Spectracide only kills the portion of the weed that it comes into contact with. While Spectracide is considered safer than Roundup, it does not leave a persistent residue in soil or water.

So when it comes to Spectracide vs Roundup, which weed killer do you choose? We have trialed two popular weed killers to establish which was the best – Roundup Weed and Grass Killer Concentrate Plus, and Spectracide Weed and Grass Killer Concentrate.

In the rest of the article, we will take a deep dive into the differences between the two products.

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spectracide vs roundup

Spectracide vs Roundup – Head to Head

Roundup Weed & Grass Killer Concentrate Plus

The Active Ingredients in Roundup Weed & Grass Killer Concentrate Plus are:

Glyphosate kills weeds (especially broadleaf), as well as combating grasses that try to compete with crops. It has been the subject of some warnings in the past which claimed it is “probably carcinogenic to humans”, but further assessments have resulted in bans on its use being lifted in some areas.

Note: A US court recently found that there is a link between glyphosate and cancer and is thus dangerous. To learn more click here.

The chemical is absorbed principally through foliage, and in small quantities around the roots. Many crops and plants have been genetically developed to be tolerant of glyphosate, so, while there’s no guarantee, it’s usually safe to use around your plants, and it will target just the weeds.

Diquat gets into the soil and attacks the weed at the roots. It’s not particularly effective in clay soil, where it requires a higher concentration.  Diquat can be fatal if swallowed, inhaled, or absorbed through the skin in significant quantities.

Spectracide Weed & Grass Killer Concentrate

The Active Ingredients in Spectracide Weed & Grass Killer Concentrate are:

Fluazifop-p-butyl is a herbicide, used to kill grasses, without harming broad-leaved plants. The half-life in soils is one to two weeks. It can be highly toxic to fish and aquatic life.

Dicamba is often used in pastures and non-crop areas to control brush and bracken. It’s toxic to conifer species but is less toxic to grasses. Dicamba works by boosting plant growth to the extent that it runs out of nutrients and dies. So, expect to see initial growth with Dicamba containing herbicides.

Conclusion on Ingredients and Safety

Regarding Active Ingredients, Roundup has the highest concentration of glyphosate, while Spectracide has the higher density of Diquat.

There are more toxicity warnings with Spectracide, and the total active ingredient content in the Roundup product is higher.

Of the two products, the Roundup Weed & Grass Killer Concentrate Plus has fewer contraindications, suggesting that it’s less toxic, but care should always be taken when applying these products.

If you’re concerned about your surrounding plants, pets, and children, then you may want to consider an alternative such as Sunday Lawn Care

Application – How To Use

Roundup Weed & Grass Killer Concentrate Plus

The Roundup product needs to be manually diluted – the lid doubles as a measuring jug, so dilution to the correct concentration is pretty straightforward (6oz per gallon of water, or 3oz per gallon for easy-to-kill weeds).

Using a tank sprayer (purchased separately), you spray the weeds you want to kill until the leaves are thoroughly wet. If you accidentally spray a plant that you don’t want to kill, you need to rinse it thoroughly with water. It’s safe for people and pets to enter treated areas once the spray has dried. It’s rainproof within 30 minutes.

It’s recommended to apply Roundup while weeds are actively growing and during warm, sunny weather. Weeds will begin to wilt within 12 hours and should be completely dead within one to two weeks.

Roundup Weed & Grass Killer Concentrate Plus can be used around fences, trees, flower beds, and driveways. It can also be used for veg patch preparation or lawn renovation.  Ornamental shrubs, bushes, and flowers can be planted one day after initial application. Vegetables, herbs, fruits, and lawn grasses can be planted three days after application.

Spectracide Weed & Grass Killer Concentrate

This particular Spectracide product is super-easy to use. Attach your water-hose attachment to the built-in diluter, turn on the faucet, and the product dilutes for you, using the hose-pipe to power the spray. This is perfect for applying to large areas.

Spray desired weeds until the leaves are wet, avoiding human and pet contact. Spray-drift can occur, so it’s essential to clear the area first. The product becomes rainfast within 15 minutes.

For best results, you should apply this product during the spring or the fall, when daytime temperatures exceed 60ºF. You shouldn’t mow the lawn for seven days before or after treatment.

If you’re using this product to clear a weedy lawn, you should wait seven days before you rake the soil and replant your seeds, or lay turf.

Conclusion on Application

Both products are fairly straightforward to use, but Spectracide Weed & Grass Killer Concentrate is the simplest because there’s no manual dilution required.

However, for smaller areas, Roundup Weed & Grass Killer Concentrate Plus is probably easier to apply but requires manual dilution and an additional spray tank.

Customer Support

The Roundup website has a help center, which includes a live chat service, a Twitter account, and a mailing address should you require any support. However, when we tried the live chat service, it wasn’t working – there was no option to leave a message or speak to someone. Perhaps it was a time-zone issue as we were accessing it during the morning in the UK, but it doesn’t particularly instill vast amounts of confidence.

The Spectracide website has quite an in-depth solution center, with categories for a wide range of application areas, such as lawns, patios, walkways, and driveways. When you click on your intended application area, the site recommends specific items from its range suitable for that type of space.

Additionally, there’s a wealth of information in a Tips & Info section, as well a Contact Us page that includes a customer service freephone number, and an opportunity to leave comments.


Roundup Weed & Grass Killer Concentrate Plus

There’s evidence of greater customer satisfaction for the Roundup product. The consensus is that it works effectively while protecting surrounding vegetation if applied carefully. However, it doesn’t appear to offer a long-term solution, as the weeds have a tendency to return.

Most customers considered Roundup to offer good value for money, and over 90% were satisfied with the overall performance.

Spectracide Weed & Grass Killer Concentrate

While there’s plenty of evidence to suggest that Spectracide products are effective at killing weeds, this is not necessarily a permanent solution. Spectracide Weed & Grass Killer Concentrate does kill weeds; and while the application is straightforward, it’s more challenging to avoid spraying surrounding vegetation

Spectracide and Roundup Alternative

If you have decided that neither Roundup or Spectracide are for you, then there is a great alternative called Sunday Lawn Care.

It’s not your standard ‘go and buy it off a shelf’ product, it is a subscription-based service that is tailored for your lawn. If there are weeds in your lawn, then the Sunday will formulate a special weed killer formula to target the weeds that are plaguing you. We have actually tried Sunday Lawn Care ourselves, and you can read the article about it here.

Use the code EHG20 at checkout to get $20 off Sunday Lawn Care

Spectracide vs Roundup Conclusion

All-in-all, we felt that Roundup has the best all-around performance, including the product with the higher concentration of Active Ingredients.

The main drawback is the manual dilution, in comparison with the ease of application with the Spectracide product. However, if you’re familiar with gardening products, such as lawn and tomato feeds, this method of application shouldn’t pose any significant issues.

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Aaron Green
Aaron is the founder of and Essential Home and Garden. He likes to spend his spare time with his family, and doing DIY projects in the home and garden.

11 thoughts on “Spectracide vs Roundup – The Showdown”

  1. I used Spectricide to kill an invasion of plantains in my garden. It worked within hours. I normally don’t use any chemicals on my property but the plantain problem was out of control. I called the manufacturer because I have deer that frequent my property. I was told to spray when they were not there and when it dried, they would be safe. I was very impressed with Sprecticide and ease of application but I worry about contamination and the wild life that visit my property. What about contamination of the water table? I worry about what can happen to my lake down below my home.

  2. I have been using Roundup and on the weeds I have been using it on, it is not particularly effective. Could I mix Spectrocide into the Roundup? I am just spot treating individual weeds that pop up.

  3. I have a small 10-year-old dog and I also have a lot of weeds can I safely use round up? Should I just keep him Away from that area for a few days or what do you suggest?

  4. I switched to Spectracide to avoid the glyphosate. I was amazed at the difference in Spectracide’s performance — two days, weeds gone! (Older, tougher weeds take a little longer.)

    Interesting that your comparison stresses whether you dilute the product. I buy the Spectracide concentrate and dilute it for my tank sprayer, just like the version of Roundup I had been using, so that argument disappears. With a tank sprayer you have a lot more control over what gets sprayed, and you don’t have to drag a hose around.

    “Greater customer satisfaction for Roundup” may have to do with the fact that Spectracide is a fairly new product, whereas Roundup has been around for quite a while, and that’s the one people know about. Does this greater satisfaction come from people who have used both products?

    Thank you for the detailed review. Side-by-side comparison of these products is hard to find.

  5. The primary active ingredient in Roundup, glyphosate, is readily available as a generic for much less than is charged for Roundup. Aside from concentrations, there is zero difference in product.

    No discussion of safety should ignore the long- and widely-discussed controversy over glyphosate’s toxicity to fish and humans. Glyphosate has a particularly bad reputation in Europe. Here are a couple of articles from the National Institute of Health on the matter.

    On glyphosate facts and fallacies:

    On glyphosate being the primary driver of the gluten intolerance epidemic:

    • Thanks for your input Chris. As with all chemicals, it pays to do your research before deciding whether to use them. There are numerous studies linked in the article, but thank you for providing these ones too for future readers.


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