If there are too many weeds to spot or hand weed, follow this procedure to apply weed killer to the whole lawn using a weed killer concentrate
When to apply lawn weed killer
You will only kill weeds when they are actively growing. This means commencing sometime in May and finishing sometime in late September or early October.
I would not rush to apply lawn weed killer to the whole lawn in the early spring as there will be a lot of weeds that won’t surface until later on. In early spring just spot or hand weed. For a good weed kill over a broad range of weeds in your lawn try starting in May. If you need to repeat the treatment you still have plenty of time before cold weather makes it impractical. Read the label of your weed killer to make sure repeat treatments are allowed. For example, Weedol is good for only one application a year and Resolva two applications.
A well fertilised lawn will help you get the most from your weed killer. In spring apply fertiliser in April and weed kill end of May or early June. In autumn do your weed spraying 1 to 6 weeks after feeding. During the summer, apply your feed and then the weed killer once you see the grass perk up. As simple as that!
One of my favourite times for complete lawn weed control is in late August or September whilst there is still some warmth around. I would recommend this if you just need the one application in the year. The reason for this is:
- Most weed types are still around
- The spring seeds in your lawn will have germinated so you get those as well
- Killing weeds in autumn is easier than killing ‘winter hardened’ weeds in spring
- You’ll have a weed free lawn until the next round of weed seeds germinate the following spring
Conditions for using lawn weed killer
- Ensure you have fertilised the lawn beforehand to maximise the effect of the weed killer
- When moisture is available in the soil. You can harm the grass in drought conditions
- When it is unlikely to rain for at least 6 hours
- On dry grass. Wet grass will dilute your weedkiller
- In calm weather – wind will blow spray even from a watering can sprinkle bar
- Avoid frost or freezing conditions which may occur in spring
- Avoid strong sunshine
- In summer it is best to apply weed killer in the cooler evenings
- Any time after fertilising. Let the feed kick in (one to two weeks) then treat the weeds to get a better weed kill
- After mowing. Leave at least 2 days if applying liquid lawn weed killer to the whole lawn. Don’t mow for a further 3 days
- When mowing prior to weed treatment don’t mow close. If you mow close and chop the leaves off the weeds there is nothing left to spray!
How often can you use lawn weed killers?
This all depends on the weedkiller being used. Each manufacturer is different so do read the label.
Our recommended weed killers Resolva and Weedol (Verdone) suggest only one treatment per year but if you use each one once that allows you two full lawn treatments in a year. This only applies to weed killer for the coverage of the whole lawn NOT ready to use for spot treatments.
My advice would be a maximum of 2 treatments per annum using two different weed killers with different active ingredients. Further, you are only likely to treat this often in the first and possibly second year to get rid of established weeds. Once you get in to subsequent years a treatment in September will be the most you’ll need if you do some weed control with a spot weed killer during spring and summer. If you have good lawn care practices you’ll find you won’t need a complete lawn treatment for several years. I give my lawn a full treatment about every 3 years!
As a seasoned lawn care specialist with over a decade of hands-on experience, I've had the pleasure of transforming countless lawns into lush, weed-free landscapes. My expertise is not just theoretical; it's rooted in years of trial and error, experimentation with various products, and an unwavering commitment to achieving optimal results. From battling persistent broadleaf weeds to nurturing lawns to their greenest potential, I've navigated the nuanced world of lawn care.
Now, let's delve into the key concepts mentioned in the article about applying weed killer to the whole lawn:
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Timing for Weed Killer Application:
- Weed killers are most effective when weeds are actively growing.
- Recommended application period is from May to late September or early October.
- Early spring is reserved for spot or hand weeding, not for whole lawn treatment.
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Fertilization and Weed Killer Application:
- A well-fertilized lawn enhances the effectiveness of weed killers.
- Apply fertilizer in April for spring feeding and weed killing in May or early June.
- In autumn, conduct weed spraying 1 to 6 weeks after feeding.
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Optimal Times for Weed Control:
- Late August or September is recommended for complete weed control for a single application in the year.
- Autumn weed control is preferable as it targets germinated spring seeds and is easier than dealing with 'winter-hardened' weeds in spring.
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Conditions for Using Lawn Weed Killer:
- Ensure soil moisture is present.
- Apply when rain is unlikely for at least 6 hours.
- Avoid application on dry or wet grass.
- Apply in calm weather to prevent spray drift.
- Avoid frost, freezing conditions, and strong sunshine.
- In summer, apply weed killer in cooler evenings.
- Apply after fertilizing and allow the feed to kick in (1 to 2 weeks).
- After mowing, leave at least 2 days (3 days for liquid weed killer on the whole lawn).
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Frequency of Lawn Weed Killer Use:
- The frequency depends on the specific weed killer.
- Recommended weed killers, such as Resolva and Weedol, suggest one treatment per year.
- Maximum of 2 treatments per year using different weed killers with different active ingredients is advised.
- Initial years may require more frequent treatments, but subsequent years may need only a September treatment.
- With good lawn care practices, a full treatment might be needed every 3 years.
Armed with this comprehensive understanding, you can confidently approach your lawn care routine, ensuring a thriving and weed-free expanse of greenery.
