15 Tips to Choose a Lawn Weed Killer

Garden lovers fall into various categories. Some want a healthy harvest. By any means necessary. Others are one with nature so they’re religious about organics and obsessively minimising carbon footprints. The section you ascribe to will dictate your weed control.

If environmental protection is important to you, you’re unlikely to kill your weeds at all. At least not with any chemical. But if your gardening principles are little more fast and loose, you’ll have a wider selection of herbicides. So let’s explore how to choose a lawn weed killer.

How to Choose a Lawn Weed Killer

Tip #1: Consider Your Location

Where in the UK do you live? England is a relatively small island, and even if you include Scotland, N. Ireland, and Wales, we’re still in the same time zone and climate belt. So we all have similar plants and closely related weeds. Meaning your choice of weed killer will probably work anywhere in the UK. But there’s still the issue of shipping and availability.

In the US, homeowners buy supplies at Home Depot or similar stores. Plus they have about six time zones and multiple weather patterns. So every area may have separate stock lists, even if it’s the same franchise. For our purposes, pick herbicide brands that are available near you. It’s frustrating when freight costs more than the product price itself.

Tip #2: Base It On The Weeds

Identifying weeds isn’t as easy as you’d think. Even the experts struggle sometimes, taking the admitted shortcut of labelling everything ‘curly doc’. Weeds are plants growing where they shouldn’t. So vegetables growing amid your grass patch could be considered weeds. But generally speaking, weeds are described as broadleaf, sedge, or grassy weeds.

If you can, dig even deeper and identify the specific weed by name. There are thousands of websites that include detailed photos and even videos. The more accurately you can name the weed, the better. This will help you find a weed killer which targets that exact weed. As you research, you may find weed clusters that respond to the same herbicide brand.

Tip #3: Think About The Grass

To the average eye, grass is grass. And the neighbour’s is always greener. But there are different species and your lawn probably has at least three or four types. The most common classification is warm-season grass vs cold-season grass. The former includes tropical places that rarely see snow. The later grow in areas with extreme temperatures and icy winters.

You want herbicides that will kill the weeds while protecting your grass. But because weeds are sometimes unwanted grass species, you might buy herbicides that accidentally targets your grass. Confirm the grass growing in your garden to ensure your chosen weed killer won’t end up damaging desired varieties of grass. Especially for deliberately mixed gardens.

Tip #4: Pick Pre or Post-Emergent

Pre-emergent herbicides kill weeds before they sprout. They create a protective film on the soil that stops weedy seeds from germinating. So you have to apply it long before any weeds appear. The best time is late winter or early spring while you’re dethatching.

So if you’re applying weed killer early in the planting season, use a pre-emergent variety of weed killer. But if your grass is well on its way and you can see the tops of unwanted leaves and flowers, opt for a post-emergent. It’s more effective and it’s easier to target the species.

Tip #5: Find the Right Season

The weather is largely gloomy in our part of the world. It’s good for grass though, since rainfall ranges from roughly 30 to 70mm, depending on the time of year. Temperatures range from sub-zero to over 20°C. Pre-emergent weed killers need soil temperatures of 10 ° C to 12°C to be effective. That’s the approximate soil temperature for germination.

When the soil rises above that – even if you can’t see any leafy weed sprouts – the seeds are popping below the soil level. At that point, any weed killer you use has to be post-emergent or it won’t have any effect. So consider the time of year and double-check with a thermometer. If yours is marked ‘in American’ you want reading that’s well below 55°F.

Tip #6: Don’t Discount Your Skill Level

Just because you enjoy gardens doesn’t mean your thumbs are green. Maybe you’re a novice lawn owner with a few hours to spare. You spotted those tell-tale yellow flowers and decided to do some weeding. You probably shouldn’t buy herbicides intended for professional use. They’re concentrated so you may hurt yourself and damage your lawn in the process.

So if you’re a domestic user, make sure the weed killer you buy is designed for layman’s usage. And if you’re a landscaping intern, talk to the boss for guidance. They won’t want you arriving at the client site with a DIY-style spray bottle. Even though technically, that might be where your skill level lies, pun intended. If in doubt, ask a trusted gardening pal for advice.

Tip #7: Pick a Joint or Dedicated Weed Killer

Are your weeds annual or perennial? Yearly weeds grow fast and spread far. They know they don’t have long to live, so they live their lives to the fullest. Their motto is definitely ‘go forth and multiply’. Perennial plants are aware they have all the time in the world. So while your lawnmower growls ‘off with their heads’ … their deep, vibrant root system says ‘I’ll be back’.

For yearly weeds, you might get away with a pre-emergent. You can re-apply them every twelve months. But for your perennials, you need something stronger. This could mean opting for a lawn weed and feed product. Or you might prefer a dedicated product – many landscapers avoid weed and feed for ethical reasons, so you may want to follow their lead.

Tip #8: Choose Between Liquid vs Solid Herbicides

Plant chemicals come in various formats. Liquids seem to be the most convenient. There’s something cathartic about squeezing the trigger on a spray bottle. Watching those speeding droplets can be soothing as well … and it’s certainly fun for the kids. But liquid herbicides come as a concentrate so mixing it at home may be a challenge for a novice. It’s a lot of work.

On the other hand, solid or dry herbicides are packaged as granules. Some people prefer these because it doesn’t need complex mixing and endless maths. You just ‘open the bag and serve’. You may need to water the lawn first – it helps the herbicide grains effectively cling to the leaves and seep into the soil. But you risk the granules being eaten by birds, pets, or kids.

Tip #9: Plan for Application

As you ponder how to choose a lawn weed killer, the top factor is dissemination. How exactly will the herbicide end up on the lawn? If you buy a concentrate, 5 litres could last 20 years. Assuming it won’t expire. And assuming you mix it correctly. This type of concentrate will need to be diluted and/or connected to a hose. Some weed killers come with a built-in tap.

This tap comes ready to connect to the garden hose. You don’t have to adjust or calibrate – just link and spray. Supermarket weed killers are ready-to-use as well. You’ll see them marked RTU and they come complete with a spray bottle and spray nozzle. But these are best for small lawns. With dry herbicide, you’ll need a rotary device or a wheeled wagon spreader.

Tip #10: Base It On the Weed Volume

Base It On the Weed Volume
The Salutation Gardens

How large is your lawn? And how many weeds have you spotted? If the weeds are dotted around the yard at specific spots, it’s probably best to buy an over-the-counter spray bottle. Their formulations are weaker than professional products. But they’re ready to use so you’re less likely to ‘overdose’ your yard and kill your grass. And they’re consumer-friendly as well.

So even if you’re the type of klutz that can kill a cactus, you can effectively apply this herbicide. Just point and spray! But if your weeds cover a larger area and have taken over the lawn, you need a weed killer that connects to the hose or sprinkler system. This way, it reaches further faster and with less effort. You may need to hire a landscaper to help though.

Tip #11: Study the Soil Cover

… or more to the point, look at the type of soil and the species of weeds. They can sometimes offer hints on what weed killer you should buy. Leguminous weeds offer clues to low nitrogen content. These include species like clover, ivy, and sandbur. So if you’re using weed and feed, get one that’s high in nitrates. At the other end of the spectrum and weedy mosses and algae.

These weeds are non-vascular so they may imply poor drainage and over-watering. And if you’re seeing lots of crabgrass and bluegrass, you might be cutting your grass too short so let it grow out a little more. Using weeds as harbingers in this way will make it easier to pick the right weed killer. And because your results will be targeted, the rest of your lawn will love it!

Tip #12: Think About Performance

Think About Performance
The Salutation Gardens

Weed killers can be ‘external’ contact herbicides or ‘internal’ system herbicides. Contact herbicides are mostly broadleaf weed killers. They land on the leaves and kill them. Because the plant can no longer photosynthesise, it dies within a day or two. Problem solved!

System herbicides get ‘on the inside’ of the plant, poisoning its sap, stem, and roots as well as its leaves. These herbicides are more slow-acting. And they’ll pass on to any pest (or pet) that eats the weeds. And depending on the number of weed varieties in your lawn, you may want a specifically targeted herbicide or a broad spectrum variant that cuts across multiple species.

Tip #13: Check the Law Books

Gardening products come in all shapes and sizes, and some of them are banned. Weed and feed products – for example – are illegal in Canada and frowned upon locally. And even in a place with fewer restrictions, certain types of garden chemicals are unwanted. Glyphosate is on a short leash and while it’s mainly a pesticide, it’s also used in herbicides so watch out.

Herbicides can leach into the neighbourhood water supply. So even if the chemicals in your herbicide aren’t banned outright, check with you municipal council or your HoA. They might have regional guidelines that dictate which weed killers you can (and can’t) use in your area.

Tip #14: Consider the Active Ingredient

Consider the Active Ingredient
The Salutation Gardens

Legality aside, different herbicides use different formulations and mixes. Concentrated weed killers need deep dilution and you should only mix as much as you need. It will go bad shortly after mixing, so you have to carefully measure the right amount to avoid wastage.

We’ve already mentioned glyphosate. Other chemicals used in herbicides include dicamba, MCPA, mecoprop P, clopyralid, and fluroxypyr. Some of these chemicals are pet-friendly. Others are soluble and only become safe after they dry … but they can take hours to dry.

Tip #15: Read the Label

This should probably be the first step as you consider how to choose a lawn weed killer. But so few people read instruction booklets. And those that do rarely follow the guidelines. So by putting this point last, we’re priming you with information and seeding you with knowledge, pun intended. This way, as you finally read the guidelines, they’ll subconsciously sink in.

Your mind will intuitively spot familiar words and relevant information. You’ll know what’s important because you’ll have glanced at it before while reading this article. So as you peruse the product label on your weed killer, you’ll automatically be on the lookout. Confirm the type of grass, class of weeds, notes on weather, hints on dosage, and recommended methods.

How are you managing your garden weeds? Share your weeding secrets in the comments!

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