How does Weed and Feed Work and How Long Does it Take?

While using a weed and feed product may seem like a good idea because you’re completing two tasks with one application, it is not always the best solution for keeping your lawn nice and healthy.

There are numerous weed and feed products on the market and they have become quite popular over recent years. They promise to not only kill the weeds in your lawn but also add important nutrients.

This means that time-poor gardeners have been attracted to using these products in an effort to make maintaining the lawn easier and faster.

But, how do these products work and are they effective?

Perhaps, they’re not the best solution for all gardeners but may be a good solution for others. We’ll have a look at the pros and cons a little later to help you decide if they are the right option for you.

How does weed and feed work?

Weed and feed contains a number of active ingredients. The herbicide contained in most weed and feed products is Dicamba. This is designed to kill most broadleaf weeds such as dandelions, clover, thistles, capeweed, bindii, cudweed and flatweeds.

lawn weed | Lawn care

However, the amount of Dicamba in most weed and feed products is quite low so it can take a number of applications to be totally effective. 

Nutrients are also included but these are mainly restricted to nitrogen and iron.

While these are important for lawn growth and help to keep the lawn green, they don’t provide all the nutrients that a healthy lawn needs.

For healthy plant growth, three important nutrients are necessary: nitrogen, phosphorus and potassium. Weed and feed products generally lack the latter two.

How long does weed and feed take to work?

Manufacturers of weed and feed products such as Yates, state that it can take around 3 weeks for the weeds in your lawn to die. This is because the herbicide is designed to be slow-acting.

Once applied, the product is absorbed by the leaves of the weeds and slowly starts killing them. The product does need to be slow-acting so that it doesn’t harm your grass in the process.

After applying weed and feed, you should see some improvement in the colour of your lawn within a few days as the grass roots take up the extra nitrogen and iron that has been added to the soil.

field lawn | Lawn care

RELATED: The Best Homemade Weed Killers

Is weed and feed any good?

While using a weed and feed product may seem like a good idea because you’re completing two tasks with one application, it is not always a good solution to keeping your lawn nice and healthy.

You see, with dual-purpose products, there always has to be a compromise because the products are designed to do two completely different tasks.  

This applies to most if not all weed and feed products. The herbicide component is quite low so that it doesn’t harm your lawn, especially if you’re not too careful about how you apply it.

On the other hand, these products also don’t contain all the essential nutrients that are necessary for healthy plant growth. 

Let’s have a look at the pros and cons of using weed and feed on your lawn.



For busy gardeners, using one product to complete two different tasks can be a huge time-saver. Weed and feed products are available in both liquid form and as granules.


As you’re only purchasing one product, you’re saving money by not having to purchase both a herbicide and a fertiliser.

Easy to apply

With the liquid application, all you have to do is attach the bottle to your garden hose and spray the contents over your lawn.

On the other hand, the granules can just be broadcast over the entire lawn area in an even manner using a fertiliser spreader.

fertilizer hand spreader | Lawn care


While there are a few benefits to using a product like weed and feed, there are also quite a number of disadvantages.

Can’t be used on all types of grass

While weed and feed products are safe to use on fine-bladed grasses such as Kikuyu and Couch, they shouldn’t be used on broad-bladed grasses such as Buffalo

However, some manufacturers like Yates, have come up with a different product that doesn’t contain Dicamba as a herbicide and is safe to use on established buffalo. This particular product contains selective weedkillers, namely bromoxynil and MCPA. 

But, even this product is not safe to use on certain Buffalo varieties such as ST26 and ST85.

May need more‌ than one application

Because weed and feed products only contain a low concentration of herbicides, they may not effectively kill all the weeds in your lawn with the first application.

weed and feed 1 | Lawn care

Generally, you’ll need a second or even a third application to effectively kill all the weeds in your lawn.

Does not contain all the essential nutrients

For optimum growth and health, your lawn needs not only nitrogen and iron. It also needs the other two essential nutrients, phosphorus and potassium.

Phosphorus is particularly important for good root development and strength, while potassium helps to strengthen the grass itself. 

Lawn Fertilizer | Lawn care

This means that if you want a truly healthy lawn, you’re going to have to apply a separate fertiliser anyway.

Promotes excessive use of herbicides

As weed and feed products are designed to be applied all over your lawn, you may be applying a herbicide in areas where it’s not actually needed.

For example, if your lawn only has a small patch of weeds in one area or there are only a few weeds scattered here and there, is applying a herbicide to the entire lawn really necessary?

In this instance, you might be better off digging out the weeds by hand or using a spot-on herbicide instead.

Excessive nitrogen can wash into nearby waterways

Weed and feed products contain quick-release lawn fertiliser that the grass has to absorb as quickly as possible.

If there’s an oversupply of nitrogen, the excess can leach out of the soil and end up in nearby waterways.

This is very bad for the natural ecosystem because it creates algal blooms that will suffocate other aquatic life.

Is there a weed and feed alternative?

As you can see, although there are a few advantages to using a weed and feed product, if you care about the health of your lawn, there are better solutions.

You can control most types of weeds either by removing sparse ones by hand or applying a recommended broadleaf herbicide on the weeded sections.

weeding tool 4 | Lawn care

To keep your lawn nice and healthy, use a fertiliser that is primarily designed for optimum lawn health and contains adequate amounts of nitrogen, phosphorus, potassium and iron.


Does weed and feed work on all weeds?

Weed and feed is designed to work only on broadleaf weeds, such as bindii, clover, dandelion and flatweed.

When should you weed and feed your lawn in Australia?

In summer-growing lawns, weed and feed should be applied in spring. This is the time that weeds will be most active and the grass is starting to grow again.

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Annette Hird

Annette Hird is a gardening expert with many years of experience in a range of gardening related positions. She has an Associate Diploma of Applied Science in Horticulture and has worked in a variety of production nurseries, primarily as a propagator. She has also been responsible for a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.


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