- Three Classes of Weeds: Broadleaf, Grassy, Sedge<\/a><\/li>
- Annual and Perennial Weeds<\/a><\/li>
- Identify Your Weeds<\/a><\/li>
- Herbicide Formulations: Liquid, Granular, Selective, Nonselective<\/a><\/li>
- Pre-Emergent, Post-Emergent, and Weed and Feed<\/a><\/li>
- When to Apply Herbicides<\/a><\/li>
- How to Spray Weeds in Your Lawn<\/a><\/li>
- Raising a Weed-Free Lawn<\/a><\/li>
- FAQ<\/a><\/li><\/ul> \t\t\t<\/div> \t\t<\/div><\/div>
Three Classes of Weeds: Broadleaf, Grassy, Sedge<\/h2>
The first step to controlling weeds is to know your target. Weeds fall into three classes<\/a>: broadleaf, grassy, and sedge.<\/p>
Broadleaf weeds<\/strong> produce two seed leaves as the plant emerges, generally displaying broader leaves and branched stems. Broadleaf weeds include:<\/p>
- White clover<\/li>
- Dandelion<\/li>
- Thistle<\/li>
- Pokeweed<\/li>
- Poison ivy<\/li> <\/ul>
Grassy weeds<\/strong> produce one seed leaf, like regular turfgrass. Examples of grassy weeds include:<\/p>
- Goosegrass<\/li>
- Crabgrass<\/li>
- Rushes<\/li> <\/ul>
Sedges<\/strong> also make just one seed leaf, but in cross-section, the leaves show a triangular shape, as with: <\/p>
- Yellow nutsedge<\/li> <\/ul>
Annual and Perennial Weeds<\/h2>
![\"Perennial](\"https:\/\/www.lawnstarter.com\/blog\/wp-content\/uploads\/2022\/10\/14457225751_645a3784fd_c-1.jpg\")
Photo Credit: NY State IPM Program at Cornell University<\/a> \/ Flickr \/ CC BY 2.0<\/a><\/figcaption><\/figure> Weeds have one of two types of growing habits \u2014 annual and perennial. <\/p>
- Annual weeds<\/strong> live for just one season, which makes them easier to control.
<\/li>- Perennial weeds<\/strong>, such as dandelions or crabgrass, recur yearly from the same root system.<\/li> <\/ul>
According to horticulture agent Mary Helen Ferguson with the Louisiana State University Extension in Livingston Parish, \u201cOnce an annual weed has flowered and gone to seed, it\u2019s already done most of its damage and will die soon anyway. Once a seed has developed, that seed will be in the soil for the following years.\u201d<\/p>
Identify Your Weeds<\/h2>
Before you head to the store to pick up weed killer, identify the weeds first<\/a>. If you are looking for more help with weed identification, there are helpful sources available: <\/p>
- The Weed Science Society of America<\/a> (WSSA) is a non-profit organization that promotes the understanding of weeds and their effects on the environment. They also offer a gallery of weed photos to help homeowners identify their culprit.<\/li>
- Your local County Extension Service<\/a> can also help you to ID your weeds.<\/li> <\/ol>
Herbicide Formulations: Liquid, Granular, Selective, Nonselective<\/h2>
Now that you know your weed type, you face more choices. Do you want to use a liquid or granular herbicide? Selective or nonselective? \u201cThe type of product that\u2019s best will depend on the type of weed you\u2019re trying to kill and the type of turfgrass that you have,\u201d says Ferguson. <\/p>
Decide which will work for you based on the bullet points below: <\/p>
- Liquid herbicides<\/strong> are usually mixed with water and sprayed from a handheld or backpack pump sprayer<\/a>.<\/li>
- Granular herbicides<\/strong> are mixed with an inert carrier like clay, lime, or a fertilized carrier and spread from a fertilizer spreader<\/a>.<\/li>
- Selective herbicides<\/strong> kill specific plants. It is selective if the label says \u201cbroadleaf herbicide\u201d or something similar. If you follow the label directions, you can spray it, and it will kill the weeds without killing your grass.<\/li>
- Nonselective herbicides<\/strong> kill whatever they touch. For these, you need a spray bottle and careful aim.<\/li> <\/ul>
Two Types of Spraying: Broadcast Or Spot<\/h3>
When it comes to yard spraying, it’s crucial to identify whether you should use the broadcast or spot spray technique based on the area you intend to treat and what\u2019s in it (plants and landscaping). Don\u2019t mix them up, or you could kill your lawn.<\/p>
- Broadcast<\/strong> spraying<\/strong> is applying the herbicide across the entire lawn. You broadcast spray selective weed killer since the grass can tolerate it.<\/li>
- Spot treatments<\/strong> use an applicator, like a pressurized sprayer, to apply the herbicide directly to the weed so no other plants are affected. Easier to use around patios and on sidewalks.<\/li> <\/ul>
Now that you know the differences between the major categories of herbicides, see our list of the best weed killers<\/a> on the market to find the best weed spray for lawns.<\/p>
Pre-Emergent, Post-Emergent, and Weed and Feed<\/h2>
![\"Spraying](\"https:\/\/www.lawnstarter.com\/blog\/wp-content\/uploads\/2019\/07\/rsz_pixnio-46933-800x533-1.jpg\")
Photo Credit: Cade Martin, Dawn Arlotta, USCDCP<\/a> \/ Pixnio<\/figcaption><\/figure> Pre-Emergent Herbicides<\/h3>
A pre-emergent herbicide<\/a> can be especially helpful as a crabgrass killer and for places in your lawn where weeds pop up yearly. <\/p>
Pre-emergent herbicides need precise timing. The critical number is 52: Crabgrass and other seeds begin to germinate when the soil temperature<\/a> (not the air temperature) hits 52 degrees Fahrenheit. You must apply the pre-emergent herbicide before that moment for them to be effective.<\/p>
\u201cPre-emergence herbicides are only appropriate for weeds that come back from seed, and they generally work better on small-seeded weeds,\u201d Ferguson says. \u201cThey\u2019re most often used for annual grasses like crabgrass.\u201d<\/p>
Post-Emergent Herbicides <\/h3>
A post-emergent herbicide<\/a> targets existing weeds and is especially helpful in places such as driveways or sidewalks. According to Ferguson, \u201cPost-emergence herbicides are best applied<\/a> early enough in the life of a weed to kill the weed while it\u2019s still small before it flowers and produces seed.\u201d<\/p>Weed and Feed<\/h3>
A weed and feed<\/a> is a herbicide that includes a fertilizer. This product catches a lot of grief from some gardeners and environmentalists since its application is hard to get correct and easy to abuse. The best time to apply fertilizers is often the wrong time to use a weed killer and vice versa. People often get it wrong.<\/p>
Ferguson notes, \u201cFor example, here in Louisiana, the appropriate time for making an initial application of a pre-emergence herbicide for crabgrass is earlier than the time when nitrogen-containing fertilizer should be applied.\u201d <\/p>
Keeping your herbicide and fertilizer treatments separate will help your grass in the long run.<\/p>
When to Apply Herbicides<\/h2>
Pre-Emergent Herbicides<\/h3>
Use pre-emergent herbicides before<\/strong> summer and winter annual weeds sprout. The key is knowing when to apply pre-emergents<\/a>:<\/p>
- Summer <\/strong>annual weeds<\/strong>:<\/strong> These weeds sprout in the spring, thrive in the summer, and set seed and die in fall and winter. Apply pre-emergent herbicide just before the soil temps reach 52 F to control pesky summer annuals like crabgrass<\/a>, foxtail, and goosegrass.<\/li>
- Winter annual weeds:<\/strong> Weeds like poa annua and filaree germinate in fall or winter, grow in the spring, and perish when the summer temps start to rise. When the soil temps reach 70 F, apply a pre-emergent to stop these weeds from sprouting above the soil surface.<\/li> <\/ul>
Post-Emergent Herbicides<\/h3>
If you procrastinated and are now too late to apply a pre-emergent, have no fear! Selective and nonselective herbicides are usable whenever you find the plants actively growing. However, these post-emergents work best early in the season when the weeds are still small.<\/p>
- Apply in spring<\/strong> (late April-early June) or early fall <\/strong>(September 15 to October 15) for the most efficient management. (Timing depends on where you live.)<\/li>
- Lightly coat the leaves<\/strong> with the weed spray. Do not saturate an area with a post-emergent herbicide. It will be washed past the plants and into the soil, where it may damage other plants or get into water sources.<\/li>
- Reapply as needed.<\/strong> Stubborn weeds may need repeated treatments at 10- to 20-day intervals to eradicate them. Again, carefully follow the label\u2019s directions about the time between sprays.<\/li> <\/ul>
How to Spray Weeds in Your Lawn<\/h2>
- Lightly coat the leaves<\/strong> with the weed spray. Do not saturate an area with a post-emergent herbicide. It will be washed past the plants and into the soil, where it may damage other plants or get into water sources.<\/li>
- Winter annual weeds:<\/strong> Weeds like poa annua and filaree germinate in fall or winter, grow in the spring, and perish when the summer temps start to rise. When the soil temps reach 70 F, apply a pre-emergent to stop these weeds from sprouting above the soil surface.<\/li> <\/ul>
- Spot treatments<\/strong> use an applicator, like a pressurized sprayer, to apply the herbicide directly to the weed so no other plants are affected. Easier to use around patios and on sidewalks.<\/li> <\/ul>
- Granular herbicides<\/strong> are mixed with an inert carrier like clay, lime, or a fertilized carrier and spread from a fertilizer spreader<\/a>.<\/li>
- Your local County Extension Service<\/a> can also help you to ID your weeds.<\/li> <\/ol>
- Perennial weeds<\/strong>, such as dandelions or crabgrass, recur yearly from the same root system.<\/li> <\/ul>
- Annual weeds<\/strong> live for just one season, which makes them easier to control.
- Yellow nutsedge<\/li> <\/ul>
- Annual and Perennial Weeds<\/a><\/li>