Lawn weed identifier and lawn check
Lawn grass weeds identification: what weed is this, and what is wrong with my lawn?
Photograph the weed, or the patch that looks wrong. The lawn check names the weed, reads brown patches, moss and yellowing, says how serious it is and plans the fix for the weeks ahead. It does not name your grass species.
The result
What the lawn check tells you about your lawn
One close photo and where the lawn is: the report is built for your region and the season.
The most likely weed, with how sure the match is and the leaf, stem and flower clues it used; or that the photo shows lawn grass with nothing wrong.
Brown patches, yellowing, bare spots or weeds, with the likely causes ranked: drought or heat stress, fungus, dog urine, compacted soil (pointed to by the weeds it brings), the wrong feed.
One plain call, in words. No lawn health score.
- Watch it
- Fix it this month
- Call a pro
Mowing height, deep or light watering, fertilization, weed control and overseeding for the next weeks, timed for your climate and the season.
The type of fertilizer, weed killer or fungicide for the weed or the problem, used at the rate and time its label gives, on the grasses its label allows.
How the lawn should change week by week if the plan works, in words, and when a new photo should show it.
The weed, the problem and the plan on one page, to show a lawn service or a garden center.
Method
How the lawn check works
- 01
Upload a close photo of the weed or the patch
Get down to the lawn: the weed with its leaves and any flower in sharp focus, or the edge of the patch where brown meets green, in daylight.
- 02
Add your ZIP code or town
Your region and climate zone decide which weeds and diseases the season brings, and when to feed, seed and treat.
- 03
Get the weed and the problem
The lawn check names the weed, or reads the brown patches, moss or yellowing, and says how serious it is.
- 04
Follow the lawn care plan
The steps for the next weeks, in order. Send a new photo later to see whether the lawn is coming back, or whether it is time to call a pro.
Reference
Identify types of lawn grass: cool-season and warm-season
The lawn check does not name your grass, but a weed killer's label names the grasses it may go on, so check yours first. These are common lawn grasses and the clues on the blade; each needs its own mowing height, water and fertilizer.
- Kentucky bluegrass (cool-season)
Dark green and medium-textured, with a boat-shaped tip and parallel sides that look stiff. Spreads by rhizomes, so it repairs worn spots; grows best in fall, winter and spring.
- Tall fescue (cool-season)
Coarse, medium to dark green, the leaf rolled in the bud. A bunch grass, so open spots may need reseeding; it tolerates heat and drought well.
- Perennial ryegrass (cool-season)
Fine-textured and rich green, the back of the leaf shiny and the tip tapered. A bunch grass that takes heavy traffic; often mixed with Kentucky bluegrass.
- Bermudagrass (warm-season)
Medium to coarse and grey-green (hybrids finer), pointed blade tips and a fringe of hairs where the blade meets the sheath. Turns brown and dormant in the cool months.
- St. Augustinegrass (warm-season)
Broad, medium-green blades with a boat-shaped tip; creeps by stolons into a dense turf. Takes shade and heat, not cold, and goes dormant in late autumn and winter.
Source: UC IPM (UC Guide to Healthy Lawns: turf species), as of
Reference
Lawn grass brown patches: what the pattern says
Where the brown is and how it appeared often points to the cause. Most lawn problems have a nonliving cause, such as water, fertilizer or a dog, though they are often blamed on insects or disease.
| What you see | What it often means |
|---|---|
| Spots that appear all at once in one area | A nonliving cause, such as water, fertilizer or something left on the grass |
| Patches that grow slowly | A disease or an insect problem |
| Damage soon after mowing, feeding or spraying | That job was not done right |
| Round spots of dead grass with a dark green ring | Dog urine, worst on bunch grasses |
| Dry spots where the sprinkler does not reach | Too little water |
| Patches that turn yellow, then brown or straw, often with green grass in the middle; the leaf base dark, rotted and smelly | Brown patch, a fungus favoured by long wet spells; herbicide damage looks similar but the leaf base stays dry |
- What you see
- Spots that appear all at once in one area
- A nonliving cause, such as water, fertilizer or something left on the grass
- What you see
- Patches that grow slowly
- A disease or an insect problem
- What you see
- Damage soon after mowing, feeding or spraying
- That job was not done right
- What you see
- Round spots of dead grass with a dark green ring
- Dog urine, worst on bunch grasses
- What you see
- Dry spots where the sprinkler does not reach
- Too little water
- What you see
- Patches that turn yellow, then brown or straw, often with green grass in the middle; the leaf base dark, rotted and smelly
- Brown patch, a fungus favoured by long wet spells; herbicide damage looks similar but the leaf base stays dry
Pull a few blades from the edge of a patch and look at the base: rot points to brown patch, a dry, tan base without a smell of rot to herbicide damage.
Source: UC IPM (UC Guide to Healthy Lawns: patterns, abiotic disorders); LSU AgCenter (Brown Patch), as of
Reference
Why is my grass turning yellow? Feed, water or a dog
Yellow grass is a symptom, not a cause. Check these before you buy anything.
- Short of nitrogen
- The most common nutrient shortage in lawns: the grass turns yellow and grows weakly.
- Short of iron
- Common in alkaline soils: yellow or bleached spots that mottle the blades.
- Short of potassium
- Blades turn yellow and brown at the edges.
- Water
- Too little gives dry spots; too much, on poor drainage in heat, can scald the grass and invite root disease.
- Dogs
- Round dead spots ringed with dark green grass; watering the spot soon after flushes the salts.
- Soil pH
- Turfgrass grows best at a pH of about 6 to 7; a soil test says what is short and what to add.
Source: UC IPM (UC Guide to Healthy Lawns: nutrient deficiencies, watering, dog injury), as of
Reference
Lawn grass weeds identification: broadleaves, grasses and sedges
Lawn weeds fall into three groups. The lawn check names the weed, so you know which treatments suit it; which treatments suit your grass, the label and the glossary above decide.
- Broadleaves
Weeds such as dandelion and buckhorn or broadleaf plantain.
- Weedy grasses
Crabgrass, dallisgrass and annual bluegrass look like lawn grass at first glance: the check tells them apart from the lawn around them.
- Sedges
Nutsedge is a sedge, a group of its own; pulling it by hand while it is young, before it forms tubers, helps keep it out.
- What the weed says
Many weeds point to a lawn condition, such as overwatering, compacted soil or low fertility. Fixing it is part of the plan.
- Before any weed killer
No single herbicide controls all lawn weeds, and not all can be used on every grass: the check names the weed, and the glossary above helps you name the grass, before you choose.
Source: UC IPM (Weed Management in Lawns), as of
Photos
How to photograph a weed or a patch for the lawn check
Weeds differ in the leaf, the stem and the flower, and a patch tells its story at its edge, so the photo has to be close, not the whole yard.
Do
Get close
The weed fills the frame: the leaf shape, the stem and any flower are the main clues.
Or pull one and lay it down
Instead, pull one weed with its roots and lay it on a sheet of paper for the photo.
Use daylight
Out of harsh midday sun, so yellow and grey-green look as they do.
Shoot the edge of a patch
In the same close shot: where brown meets green shows how a problem is spreading.
Don't
No wide yard shots alone
A whole lawn from the porch hides the weed and the edge of the patch.
Not right after mowing
Mowing takes the flowers and the tops off the weeds, and they are the quickest clue: photograph before you mow, or find one the mower missed.
No flash at dusk
Flash can change the colour; daylight shows it best.
Treating a lawn with children or pets on it?
Read the whole label of any weed killer, fungicide or fertilizer, and keep children and pets off the lawn for as long as it says. The plan names the type of product for the weed or the problem; the label sets the rate, the timing and the grasses it may go on.
Scope
What the lawn check can and cannot tell from a photo
A photo can show
- Common lawn weeds: broadleaves such as dandelion, clover and plantain, weedy grasses such as crabgrass, and sedges such as nutsedge
- Brown patches, yellowing, moss, dry or worn spots, fairy rings and snow mould
- The likely causes, ranked, and how serious the problem is
- A lawn care plan for your region and season
Only an expert with it in hand can tell
- The species of your lawn grass: the glossary above gives the blade clues to check it yourself
- Grubs, roots and soil below the surface: dig a small square to look
- A lab test of soil or a sample: a soil test or an extension office can run one
- Whether a treated lawn is safe for pets and children: the product label says
The lawn check names the weed or the problem and goes on to a step-by-step plan for the weeks ahead, with a clear line on when to call a professional.
Next
After the lawn check: when to get help
The plan covers the fixes you can do at home. Some problems need a test or a person on the lawn.
- 01
Test the soil, don't guess
Before you feed, a professional soil analysis says which nutrients are short and what to add to reach the right pH for your grass.
- 02
Fix the water first
Check for broken or blocked sprinkler heads and uneven coverage before you treat a dry or yellow area.
- 03
Ask your extension office
A local Cooperative Extension office can name a problem the photo cannot settle, such as a disease or insects in the soil.
- 04
Call a pro for a spreading patch
When the plan says "Call a pro", or a patch keeps growing after you have fixed the water and the feed.
Lawn check online: no app to install
The lawn check runs in the browser on your phone, out on the lawn. No lawn expertise required. Trying the form here is free: no card, no account and no trial, so there is nothing to cancel.
Limits
What a lawn photo cannot settle
The lawn check gives the most likely weed and cause, not a certainty: mixed lawns, soil and local climate can confuse a photo. It does not name your grass species. Follow the label of every lawn product, and keep children and pets off a treated lawn for as long as it says.
FAQ
Lawn check questions
Is there an app that can tell me what kind of grass I have from a photo for free?
This tool names lawn weeds and problems, not the grass; the glossary on this page gives the blade clues for the common lawn grasses. It works in the browser on a phone, with nothing to install, and the form is free to try: no card, no account and no trial.
How can I identify the type of grass on my lawn?
Look at the blade up close: its tip (boat-shaped or pointed), its width, its colour, and how it grows (spreading or in bunches), and match it to the glossary above. The lawn check itself names weeds and problems, not the grass.
Can I identify a lawn weed from a picture, and how accurate is it?
A close photo of the weed in daylight, leaves and flower in focus, is the place to start. The report shows how sure the match is, the clues it used and the look-alikes it was told apart from.
Is this a grass identifier or a lawn diagnosis tool?
A lawn diagnosis tool. It names the weed or the problem in the photo and gives a lawn care plan for your region. It does not name the grass species.
Is it more than a lawn weed identifier?
Yes. Besides the weed it reads brown patches, yellowing, moss and dry or worn spots, says how serious they are, and gives the steps to fix them, with a summary to share with a lawn service.
What do I get after the identification: a care plan or just the weed's name?
A care plan: mowing, watering, fertilization, weed control and overseeding for the weeks ahead, timed for your region and the season.
How do I know what kind of grass I have for better lawn care and fertilizer timing?
Grass types need different mowing heights, water and fertilizer, and cool-season and warm-season grasses grow at different times of the year. Match your blade to the glossary on this page; the lawn check does not name the grass, and its plan sets the timing by your region and the season.
How can I tell what kind of grass I have so I can safely treat these weeds?
Photograph the weed, and the check names it. Then match your grass to the glossary above: no single weed killer controls every lawn weed, and not every one can be used on every grass (UC IPM). The plan names a type that fits the weed, and the label says which grasses it may go on.
Can I do grass weeds identification from pictures?
Yes. Photograph the weed up close, leaves and stem in focus. The lawn check tells broadleaves, weedy grasses such as crabgrass, and sedges such as nutsedge apart, and names the weed.
What is wrong with my lawn when I see brown patches?
Spots that appear all at once usually have a nonliving cause, such as water or fertilizer; patches that grow slowly point to disease or insects (UC IPM). Round dead spots with a dark green ring are often dog urine.
How to get rid of brown spot disease in my lawn?
For brown patch, LSU AgCenter names water and nutrient management the two most important cultural controls: water only when needed, in the early morning, and avoid heavy nitrogen when the disease is likely. LSU calls the proper use of fungicides the surest control, used as their label says.
Will brown patches or yellow spots in my lawn go away on their own, or do I need fungicide?
It depends on the cause. A dry spot needs water; a dog spot can grow back on a creeping grass such as bermudagrass or St. Augustinegrass, but on a bunch grass such as tall fescue it may need reseeding; a nutrient shortage needs the right feed; a fungus may need a change in watering first. The plan says which, and when a fungicide is worth it.
Can grass that has turned brown or yellow be saved and become green again?
It depends on the cause. Bermudagrass turns brown and dormant in the cool months (UC IPM), which is a season, not damage. For other causes the plan says whether to wait, fix the water or the feed, or reseed.
Why does my St. Augustine grass have brown patches?
Brown patch can be the cause: LSU AgCenter notes that on St. Augustinegrass it is often mistaken for herbicide or fertilizer damage. A rotted, smelly leaf base points to the fungus.
What's the best fertilizer for yellow grass?
The one that adds what is short. Nitrogen is the most common shortage, but iron and potassium also turn grass yellow (UC IPM). A soil test, or the plan from your photo, says which.
How much should I be spending on my lawn each year?
That depends on the lawn and the region. The plan lists only the steps your lawn needs, so you do not buy products it does not.
Weeds, brown patches or yellow grass in the lawn?
Take one close photo of the weed or the edge of the problem. The lawn check names it and gives the plan.