Why can't I use Tenacity on bentgrass?

Tenacity (mesotrione) BLEACHES bentgrass and damages it severely. Mesotrione is actually used as a herbicide TO REMOVE bentgrass invading Kentucky bluegrass and fescue lawns. If you have a bentgrass lawn you want to keep, never apply Tenacity, Topramezone (Pylex), or any other HPPD-inhibitor herbicide.

Do I really need a reel mower for bentgrass?

Yes — there is no workaround. Rotary mowers tear bentgrass blades at low heights and the lawn turns brown within hours. A quality reel mower for a home bentgrass lawn starts around $1,500. If you don't want to invest in a reel mower, you don't want bentgrass — pick KBG, fescue, or perennial ryegrass instead.

How much fungicide does a bentgrass lawn need?

8 to 12 fungicide applications per year, on a preventive rotation. Bentgrass is susceptible to dollar spot, brown patch, Pythium, anthracnose, and snow mold — all of which can wipe out a lawn fast without preventive treatment. Plan on $400 to $800 per year in fungicide costs alone for a typical home lawn.

How tall should I cut bentgrass?

Home lawns: 0.5 to 0.75 inches with a reel mower. Greens height: 0.125 inches (1/8 inch). Going above 1 inch creates a 'puffy' surface and the bentgrass loses its signature density. There's no compromise mowing height for bentgrass.

Why is bentgrass considered the highest-maintenance lawn grass?

Reel mower required, daily mowing in season, daily light watering in summer, mandatory year-round fungicide program (8–12 apps), frequent top-dressing with sand, spoon-feeding fertilizer every 2 weeks, and very limited herbicide options. A bentgrass home lawn is a serious hobby — most homeowners are happier with KBG or tall fescue at 1/10th the cost and effort.

Can I overseed an existing lawn with bentgrass?

No — bentgrass can't be added to a regular lawn. It requires its own dedicated maintenance program (reel mower, daily watering, fungicides) that's incompatible with KBG, fescue, or ryegrass. If bentgrass shows up in your KBG/fescue lawn as a contamination, the standard removal product is Tenacity (mesotrione).

How often should I mow bentgrass?

Every 2–3 days during the growing season, and sometimes daily during peak growth. Bentgrass must be cut with a reel mower at 0.5–0.75 inch for home lawns. This frequent mowing schedule is one reason bentgrass is considered the highest-maintenance turfgrass.

How much does a bentgrass lawn cost to maintain?

Expect $1,500+ for a reel mower and $400–800 per year in fungicide alone. Add frequent top-dressing sand, spoon-fed fertilizer every 2–3 weeks, and daily watering in summer. A bentgrass home lawn costs 5–10x more to maintain than a Kentucky bluegrass or fescue lawn.

Cool SeasonZones 3 – 7Reel Mower Required

The Complete Guide to
Bentgrass

Golf course grass at home. Bentgrass produces the most beautiful lawn you'll ever see — but it demands a reel mower, daily attention, and a mandatory fungicide program. Not for the casual homeowner.

Right now: peak growth

October — Apply preventive snow mold fungicide before first cover

All Grass Guides|

Bermuda·Zoysia·St. Augustine·Centipede·Fescue·KBG·Ryegrass·Bentgrass

Quick Reference

Mow Height

0.5 – 0.75"

Reel mower only. Home lawns: 0.5–0.75". Greens height: 0.125". Rotary mowers will not work.

Water / Week

1.5 – 2.5"

Highest water requirement of any turfgrass. Daily light watering in summer. Morning only.

N per Year

3 – 5 lbs

Per 1,000 sqft. Spoon-feed in tiny doses (0.1–0.25 lb N per app) every 2–3 weeks.

Best Zones

3 – 7

Cool, humid climates. Pacific Northwest, Northeast, Great Lakes region.

Soil pH

5.5 – 6.5

Slightly acidic. Lime cautiously — bentgrass tolerates lower pH than most cool-season grasses.

Sun Needs

Full Sun

Needs 6+ hours direct sun. Disease pressure increases dramatically in shade.

What makes Bentgrass different

Bentgrass is the grass on golf greens. Spreads via stolons, forms a dense carpet finer than any other lawn grass, and tolerates mowing heights down to 1/8 inch. The catch: it requires a reel mower, a mandatory year-round fungicide program (it's susceptible to dollar spot, brown patch, Pythium, snow mold, anthracnose, and more), daily light watering, and frequent top-dressing. A bentgrass home lawn is a hobby — typically a 5-figure investment in equipment and inputs each year. NEVER use Tenacity (mesotrione) on bentgrass — it bleaches it.

Reel mower requiredHighest maintenanceDisease proneSpreads via stolonsDaily watering neededNO Tenacity (mesotrione)

Month-by-Month Calendar

Tap a month

October

peak growth

Mow

0.5 – 0.75" every 3 days

Water

1" per week

Fertilize

0.5 – 1 lb N per 1,000 sqft of a 4-1-2 ratio (e.g., 24-0-11)

This month's tasks

Apply preventive snow mold fungicide before first cover

Final top-dressing of the year

Spot-treat broadleaf weeds with low-rate 3-way

See the Bentgrass month-by-month playbook

The full Bentgrass calendar — every task, every month, with priority and timing for every season.

Open the Bentgrass calendar

Pre-Emergent Timing

Don't miss this window

Pre-emergent is the single most important application of the year. It prevents crabgrass, foxtail, poa annua and other weeds before they germinate. Once you see weeds, it's too late.

Spring (Crabgrass, foxtail, Poa annua Prevention)

Critical

Apply when your 5-day average soil temperature reaches 55°F. Crabgrass seeds germinate when soil temperatures reach 55°F at the 4-inch depth for several consecutive days. Pre-emergent must already be down BEFORE that — once you see the first crabgrass blade, the chemical barrier is too late. Bentgrass is particularly weed-resistant due to its density, but pre-emergent is still recommended.

Typically late Mar – early May (zone 3 – 7)Varies by zone

Timing matters more than product. Too early and it breaks down before weeds germinate. Too late and crabgrass is already growing — pre-emergent can't stop what's already up. Track your local soil temperature, not the calendar date.

What to use

Prodiamine 65 WDG (Barricade)

Specialty

Rate: 0.18 oz per 1,000 sqft

The gold-standard pre-emergent. Safe on bentgrass at label rates. Apply only in spring on lawns that won't be overseeded.

Dithiopyr (Dimension)

Specialty

Rate: Per label

Pre-emergent with early post-emergent reach-back on baby crabgrass. Safe on bentgrass.

Bensulide (Betasan)

Specialty

Rate: Per label

The classic golf-course pre-emergent. Specifically labeled for bentgrass and one of the safest options for putting-green turf.

How to check your soil temperature

Use a soil thermometer at 2–4 inch depth, or check your local extension office's soil temp map. Look for the 5-day average, not a single reading — one warm day on a bentgrass lawn doesn't mean it's time.

What's Safe to Spray

Bentgrass handles most selective herbicides well. Here's what's safe and what to avoid — organized by where you'd buy it.

Safe for Bentgrass

✓

Scotts Halts Crabgrass Preventer

Pendimethalin

Big-box pre-emergent. Apply BEFORE soil hits 55°F at 4-inch depth. Use the low rate on bentgrass.

Safe

✓

Spectracide Weed Stop

2,4-D + MCPP + Dicamba

Use the LOW rate only — bentgrass is sensitive to broadleaf herbicides at full label rates. Spot-treat only, not broadcast.

Safe

✓

Ortho WeedClear (Northern)

2,4-D + MCPP + Dicamba

Standard 3-way broadleaf mix. Use the LOW rate on bentgrass and spot-treat only.

Safe

Avoid — Will Damage Your Bentgrass

Atrazine (Bonus S, Hi-Yield Atrazine)

Atrazine

NOT safe for bentgrass. On home lawns atrazine is for Centipede only — Floratam St. Augustine is not tolerant of it (Texas A&M EHT-144) — it WILL kill bentgrass.

Unsafe

Tenacity (Mesotrione) — for cool-season

Mesotrione

NOT safe for bentgrass. Mesotrione BLEACHES bentgrass and is actually used to REMOVE bentgrass from KBG and fescue lawns. Do not apply Tenacity to a bentgrass lawn you want to keep.

Unsafe

BioAdvanced All-in-One

2,4-D + MCPP + Dicamba + Quinclorac

NOT safe for bentgrass. Quinclorac at label rates can damage bentgrass.

Unsafe

Image All-in-One Southern

Penoxsulam + Sulfentrazone + 2,4-D

NOT safe for bentgrass. Southern formula labeled for warm-season turf only.

Unsafe

A note on Weed & Feed products

Combo products like Weed & Feed are convenient — one bag, one application. But you'll get noticeably better results using fertilizer and weed control separately. Here's why:

Timing: Fertilizer and herbicide have different ideal application windows. A combo forces both at the same time, so one is always off-schedule.

Application: Herbicides work best as a spray that sticks to weed leaves. Granular weed & feed relies on granules physically touching each weed — inconsistent coverage.

Precision: Most lawns don't have weeds everywhere. Spraying weeds where they are costs less and puts fewer chemicals on your lawn than treating the whole yard.

Common Weed & Feed products you'll see at the store

Standard Northern Weed and Feed

Granular combo (fertilizer + 2,4-D + dicamba)

NOT recommended on bentgrass — full label rates are too aggressive. Apply nitrogen and herbicides separately at reduced rates.

Trimec Bentgrass Formula (liquid)

Liquid 3-way (low rate)

The only weed-killer formula specifically labeled for bentgrass tolerance. Apply separately from fertilizer at reduced rates.

Scotts Bonus S Southern

Granular combo (fertilizer + atrazine)

WARNING: contains atrazine — on home lawns that is Centipede only; Floratam St. Augustine is not tolerant of it (Texas A&M EHT-144). Do NOT use on bentgrass. Listed here so you can recognize and avoid the wrong bag at the store.

What to grab instead

Three separate products. Apply each on its own schedule. Better results, less waste, healthier lawn.

Fertilizer

Spoon-feed a slow-release 4-1-2 ratio (e.g., 16-4-8) at 0.1 – 0.25 lb N per 1,000 sqft every 2 weeks during growing season. Total 3 – 5 lbs N per 1,000 sqft per year. Bentgrass demands frequent small doses, never heavy single applications.

Pre-emergent

Prodiamine 65 WDG at 0.18 oz per 1,000 sqft, or Bensulide (Betasan) for the most golf-course-tested option. Apply when soil temps approach 55°F.

Post-emergent weed killer

Trimec Bentgrass Formula at LOW rate for broadleaf, SedgeHammer for nutsedge. NEVER Tenacity, NEVER quinclorac, NEVER atrazine on bentgrass.

Always read the product label before applying. Labels and formulations change — verify the active ingredient and grass safety on the bag before you spray.

Need to check a specific product?Herbicide Safety Checker →

Common Problems

Tap any issue to see symptoms, causes, and exactly how to fix it.

See something weird on your lawn?Ask Larry — send a photo →

Mowing Guide

Mowing is the single most impactful thing you can do for your Bentgrass lawn. Here's how to get it right.

Height: 0.5 – 0.75 inch (REEL MOWER ONLY)

Bentgrass requires a reel mower — period. Rotary mowers tear bentgrass blades and turn them brown within hours. Home lawns: 0.5 – 0.75 inches. Greens height: 0.125 inches. Reel mowers with bedknives start around $1,500 and go up from there.

Frequency: Every 2–3 days in active growth

At low heights, bentgrass must be mowed every 2–3 days to follow the 1/3 rule. Skipping a day means scalping. Daily mowing is common on golf greens — and on serious home bentgrass lawns.

Sharpen reel and bedknife frequently

A dull reel cuts ragged edges that brown out within hours and invite disease. Adjust the bedknife monthly and back-lap or sharpen the reel every 50–80 hours of use. This is precision equipment.

Clippings: Bag in disease season, mulch otherwise

Bag clippings during peak disease pressure (June – August) to remove infected tissue. Otherwise mulch back to return nitrogen.

Top-dress with sand regularly

Light sand top-dressing every 2–4 weeks during growing season smooths the surface, dilutes thatch, and is standard practice on bentgrass greens. Without top-dressing, bentgrass thatch builds up fast.

Mow when the lawn is dry

Wet bentgrass clumps badly under the reel and the wheels leave tracks. Wet mowing also spreads dollar spot, brown patch, and Pythium from infected blades to healthy ones.

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