Hawaii Lawn Care Calendar 2026: Fall & Spring Task Dates

Q: When should I overseed my lawn in Hawaii?

Hawaii has no frost-driven overseeding window; the state's lawns are warm-season grasses that are sprigged, plugged, or seeded in late spring.

Q: When should I fertilize my lawn in the fall in Hawaii?

Hawaii lawns are fed on a rainfall calendar rather than a frost calendar; UH CTAHR Cooperative Extension recommends timing fertilizer for the drier months.

Q: When do you plant garlic in Hawaii?

Garlic in Hawaii is planted in the cool season (November to January) rather than against a frost date; pre-chilled cloves bulb best.

Q: When should I aerate my lawn in Hawaii?

Aerate Hawaii warm-season lawns April 15 to June 30, in late spring into early summer when bermuda, zoysia, and St. Augustine are growing fastest and can fill the holes. Use a plug aerator on moist (not wet) soil and leave the cores to break down.

Q: When should I winterize my sprinklers in Hawaii?

Hawaii has no freeze season, so irrigation runs year-round and never needs blowing out.

Q: When should I apply pre-emergent in Hawaii?

Spring pre-emergent for crabgrass goes down as soil at 1 to 2 inches approaches 55°F, typically January 15 to February 28 in Hawaii. Check the live soil temperature on this page before the calendar.

Q: When is the last time to mow in Hawaii?

Hawaii lawns grow year-round, and mowing only slows in the cooler, drier months.

Q: What kind of grass grows best in Hawaii?

Hawaii is a warm-season state. The common lawn grasses are Zoysia, bermudagrass, St. Augustine, seashore paspalum, centipede. Hawaii has no frost and no fall lawn season — CTAHR's calendar is driven by rainfall instead, with aeration and fertilizer timed for the drier summer months and zoysia and seashore paspalum favored for salt tolerance.

Every lawn and garden task dated to Hawaii's year-round growing calendar and live soil temperature: warm-season grasses, extension-service timing.

Hawaii lawns run year-round, with no frost-driven calendar

Grass zone

Warm-season

Aerate

Apr 15 to Jun 30

First frost

None

The Hawaii lawn year at a glance

Live · soil temp updates hourly

Warm-season

grass zone

Zoysia

none

typical first frost

frost-free

Year-round

lawn season

No reading

soil now · Honolulu

live data unavailable

Hawaii has no frost and no fall lawn season — CTAHR's calendar is driven by rainfall instead, with aeration and fertilizer timed for the drier summer months and zoysia and seashore paspalum favored for salt tolerance.

Live · this week

What to do in Hawaii right now

Tasks whose window is open or opening within three weeks, checked against live soil temperature at Honolulu (live reading unavailable, calendar only). Enter your ZIP for your own soil reading.

Nothing is due in the next three weeks. The full calendar is below.

Covers all 50 states. Windows are frost-date typicals; live soil temperature adjusts the soil-gated tasks.

The full calendar

Hawaii year-round lawn & garden calendar

Hawaii has no first frost, so none of these dates are a frost countdown.UH CTAHR Cooperative Extension times them by rainfall and active growth instead. The frost-only tasks (overseeding, the last mow, sprinkler blow-out, garlic, tulips) simply do not apply here.

Task	Typical window	Status	Why now
Core aerate	April 15 to June 30	Done for the year	Relieves compaction and opens thatch so water, air, and fertilizer reach the roots — and it is the best seedbed prep for overseeding.

Lawn with fallen leaves, half of them shredded by a mulching mower — Mulch the leaves into the lawn on the last mows: shredded leaves feed the soil, while a matted layer smothers the grass. “2023-11-02 11 25 12 A lawn with fallen leaves where half have been shredded by a mulching mower along Aquetong Lane in the Mountainview section of Ewing Township, Mercer County, New Jersey” by Famartin, CC BY-SA 4.0

Looking ahead

Hawaii spring lawn calendar

With no last-frost date to run off, spring here is set by soil temperature alone. The crabgrass trigger is 55°F at 1 to 2 inches for four or five days, not a date.

Task	Typical window	Why then
Spring pre-emergent	January 15 to February 28	Crabgrass germinates when soil at 1–2 inches holds 55°F for 4–5 consecutive days. Pre-emergent has to be in place BEFORE that — it has no effect on crabgrass that has already sprouted.
Spring grass seed	March 15 to June 15	Spring seeding is second-best (fall is better) because seedlings face summer heat and crabgrass, but it is the only window for warm-season seed, which needs 65–70°F soil.
First spring fertilizer	March 1 to April 15	Feeding too early pushes leaf growth ahead of root growth and feeds weeds — wait until the lawn is actively growing and has been mowed 2–3 times (cool-season) or is fully green (warm-season).

City by city

Soil temperature and frost countdown across Hawaii

City	Soil temp now (6 cm)	Typical first frost	Days to first frost	Typical last frost
Honolulu	loading…	rarely	none	rarely
Hilo	loading…	rarely	none	rarely
Waimea (Kamuela)	loading…	rarely	none	rarely

Soil temperature is modeled at 6 cm by Open-Meteo and read live in your browser; frost dates are NOAA 1991 to 2020 normals for each reference station.

What grows here

Hawaii lawn grasses and mowing heights

Hawaii is a warm-season state. Common lawn grasses: Zoysia, bermudagrass, St. Augustine, seashore paspalum, centipede. Warm-season grasses grow year-round here, and with no frost to force dormancy they never brown off, so establishment (sprigging, plugging, or seeding) and fertilizer follow rainfall and active growth rather than a season.

Grass	Mowing height
Bermudagrass	1 to 2 in
Zoysia	1 to 2.5 in
St. Augustine	3 to 4 in
Centipede	1.5 to 2 in
Bahiagrass	3 to 4 in

Bermudagrass lawn overseeded with perennial ryegrass — Bermudagrass overseeded with perennial ryegrass: the warm-season answer to a green winter lawn. “Bermudagrass couch overseeded with Homerun perennial ryegrass” by Gilba Solutions Pty Ltd, CC BY-SA 4.0

How to do each one

Task-by-task guide for Hawaii

Core aerate · April 15 to June 30

Why: Relieves compaction and opens thatch so water, air, and fertilizer reach the roots — and it is the best seedbed prep for overseeding.

How: Use a core (plug) aerator, not spikes, on moist soil — two passes at right angles, 20–40 holes per square foot. Leave the plugs to break down. Cool-season lawns: early fall during active growth. Warm-season lawns: late spring to early summer when bermuda and zoysia are growing hardest.

Rule: timed to local rainfall, active growth, and soil temperature rather than a frost date. · full guide →

Spring pre-emergent · January 15 to February 28

Why: Crabgrass germinates when soil at 1–2 inches holds 55°F for 4–5 consecutive days. Pre-emergent has to be in place BEFORE that — it has no effect on crabgrass that has already sprouted.

How: Watch soil temperature, not the calendar: apply prodiamine, dithiopyr, or pendimethalin as soil approaches 55°F (forsythia bloom is the old signal). Water in ½ inch within 48 hours. Dithiopyr also controls crabgrass up to about the 2-leaf stage if you run late. Do not apply where you will seed within 3–4 months.

Rule: timed to local rainfall, active growth, and soil temperature rather than a frost date. · full guide →

Spring grass seed · March 15 to June 15

Why: Spring seeding is second-best (fall is better) because seedlings face summer heat and crabgrass, but it is the only window for warm-season seed, which needs 65–70°F soil.

How: Cool-season seed germinates from 50°F soil — seed as early as the ground can be worked and skip pre-emergent on that area (or use mesotrione, which is safe on new seedings). Warm-season seed (bermuda, zoysia, centipede, buffalograss) waits for 65°F+ soil, typically late spring. Keep the top ½ inch moist until established.

Rule: timed to local rainfall, active growth, and soil temperature rather than a frost date.

First spring fertilizer · March 1 to April 15

Why: Feeding too early pushes leaf growth ahead of root growth and feeds weeds — wait until the lawn is actively growing and has been mowed 2–3 times (cool-season) or is fully green (warm-season).

How: Cool-season: a light feeding (0.5–0.75 lb N per 1,000 sq ft) in late spring; the heavy feeding belongs in fall. Warm-season: wait until bermuda, zoysia, or St. Augustine is 100% green, then 1 lb N per 1,000 sq ft; centipede gets half that, once. Never fertilize dormant warm-season turf.

Rule: timed to local rainfall, active growth, and soil temperature rather than a frost date.

Tow-behind plug aerator pulling soil cores from a lawn — Plug (core) aeration, not spikes; the cores left on the surface break down in a couple of weeks. “Plug Aerator” — Agri-Fab, Inc. — CC0

Why the dates are what they are

Soil temperature, growing degree days, and the frost anchor

Hand working loose soil in a raised bed — Soil lags air by weeks in both directions, which is why a calendar alone gets pre-emergent and bulbs wrong. “The Bundled Benefits of Soil Health 32” — USDA / Lance Cheung — Public domain

Soil temperature beats air temperature. Grass seed germinates from about 50°F soil, crabgrass from a sustained 55°F, warm-season seed from 65°F, and tulips want soil under 55°F so they root without sprouting. Soil at seed depth warms and cools far more slowly than the air above it, so a hot week in April or a cold snap in October moves the soil only a few degrees. That is why the soil-gated tasks on this page defer to the live reading over the calendar.

Growing degree days (GDD) are how turf scientists track it: daily heat accumulated above a base (usually 50°F). Crabgrass germination, for instance, lines up with roughly 200 GDD base 50°F in spring, the same signal as forsythia finishing bloom. The frost calendar is the long-run average of all that heat accounting.

What anchors the fall here. Most of the country dates its fall lawn work by counting back from the first hard freeze. Hawaii never gets one, so the calendar follows rainfall, active growth, and soil temperature instead, which is why the frost-only tasks (overseeding, the last mow, sprinkler blow-out, garlic, tulips) do not apply here and the rest run on their own schedule.

Common questions

Hawaii lawn care FAQ

When should I overseed my lawn in Hawaii?

When should I fertilize my lawn in the fall in Hawaii?

When do you plant garlic in Hawaii?

When should I aerate my lawn in Hawaii?

When should I winterize my sprinklers in Hawaii?

When should I apply pre-emergent in Hawaii?

When is the last time to mow in Hawaii?

What kind of grass grows best in Hawaii?

Keep planning

The rest of your Hawaii yard

Hawaii first frost datesWhen (and whether) the growing season ends here.Live soil temperature mapYour ZIP's 6 cm reading, 14-day trend, and germination thresholds.Hawaii fall foliagePeak color usually lands right in the overseeding window, so plan both.Hawaii tick forecastTicks stay active in leaf litter until a hard freeze, so check before yard work.

More West lawn calendars

Windows are climatological typicals computed from grass-zone and active-growth rules, cross-checked against UH CTAHR Cooperative Extension guidance. Any single year runs ±2 weeks; live soil temperature (Open-Meteo, 6 cm) is modeled, not measured. National tool: fall planting calendar by ZIP → Hero image: “2022-10-26 08 11 53 Fallen Red Maple and Saucer Magnolia leaves on a lawn in autumn along Aquetong Lane in the Mountainview section of Ewing Township, Mercer County, New Jersey” by Famartin, CC BY-SA 4.0