Plant
Wait for sustained soil heat
Warm-season lawns in Hawaii need late-spring soil warmth before seed has enough energy to germinate and spread.
HI planting calendar
When to Plant Grass Seed in Hawaii
Use this page for timing first. It starts with the planting window, then breaks the year into practical seedbed, watering, and weather decisions for Hawaii lawns.
- Best window
- Year-round planting possible; April through September preferred for fastest establishment during warmest months
- Soil rule
- Warm soil first, 65F+ soil
- USDA zones
- 10, 11, 12
- Regional focus
- Oahu / Honolulu and Maui
How to use this calendar
Start with seed type, then trust the soil
State timing is useful because frost, rainfall, soil texture, and heat stress change the risk profile. It is still a filter, not a guarantee. Confirm the grass species, soil temperature, and watering plan before you spread seed.
Local constraints
- Constant salt spray near coastlines
- Extreme rainfall variation by location
- Invasive weed species year-round
- Nematode pressure in tropical soil
- No winter dormancy period for weed control
- Rocky volcanic substrate in many areas
Avoid
Do not chase early green-up
Warm afternoons can arrive before soil is ready. Early seed often stalls, thins, or loses to weeds.
Seasonal plan
Season-by-season planting plan for Hawaii
Use the Hawaii calendar as a timing sequence: prep before the window, seed when soil temperature is right, and protect new turf through the first stress season.
Best window
Year-round planting possible; April through September preferred for fastest establishment during warmest months
Warm-season
Warm soil first
65F+ soil
March - May
Spring
- 1Apply a balanced slow-release fertilizer (16-4-8 or similar) in March to fuel the accelerating growth that comes with lengthening days and warming temperatures — even in Hawaii, spring brings a noticeable growth surge
- 2Dethatch bermudagrass lawns if the thatch layer exceeds half an inch — bermuda builds thatch aggressively in Hawaii's year-round growing season, and spring is the best time to address it before peak summer growth
- 3Core aerate compacted soils, especially on Oahu's central plain and Maui's former sugarcane land — the laterite clay in these areas compacts severely and restricts root development
- 4Apply pre-emergent herbicide for summer annual weeds, particularly crabgrass and goosegrass, which germinate when soil temperatures reach 65 degrees — in Hawaii this can be as early as February in low-elevation leeward areas
- 5Begin monitoring for armyworm caterpillars, which become active in spring — these are the most destructive lawn pest in Hawaii and can strip a bermudagrass lawn to bare soil in 48 hours if populations explode
- 6Overseed thin areas of bermudagrass lawn while soil temperatures are consistently above 70 degrees — bermuda seed germinates rapidly in Hawaii's warmth and will establish quickly with consistent moisture
June - August
Summer
- 1Increase mowing frequency to twice per week for bermudagrass during peak summer growth — maintain mowing height at 1 to 1.5 inches for bermuda and 1.5 to 2 inches for zoysiagrass
- 2Water deeply once or twice per week on leeward sides (Ewa Beach, Kihei, Kona) — even tropical locations have dry sides that need irrigation during the summer dry season when trade winds are strongest
- 3On windward sides (Kailua, Hilo, Hanalei), reduce or eliminate supplemental irrigation — natural rainfall is typically more than adequate, and overwatering promotes fungal disease in the high-humidity environment
- 4Apply a light nitrogen application (0.5 lb N per 1,000 sq ft) in early June to sustain summer growth without pushing excessive top growth that requires even more frequent mowing
- 5Monitor for chinch bug damage, particularly in bermudagrass on dry, sunny exposures — irregular brown patches that spread outward from a central point during hot, dry conditions are classic chinch bug symptoms
- 6Rinse coastal lawns with fresh water after kona wind events or storms that deposit heavy salt spray — summer kona winds blow from the south/southwest and carry more salt than standard trade winds
September - November
Fall
- 1Apply a fall fertilizer with moderate nitrogen and higher potassium (12-4-14 or similar) in September — potassium strengthens cell walls and improves stress tolerance heading into the wetter winter season
- 2Overseed bermudagrass lawns in September or October while temperatures remain above 75 degrees — this is an excellent time to thicken thin areas before the cooler, wetter winter months
- 3Address any thatch buildup that accumulated during summer's aggressive growth — vertical mowing or power raking in October gives the lawn time to recover before winter rains arrive
- 4Begin reducing mowing frequency as growth slows slightly with shorter days — once-weekly mowing may be sufficient for bermuda from November onward in most locations
- 5Apply lime to acidic soils in October — fall applications allow the lime to work into the soil profile during winter rains, raising pH before the next growing season's fertilization program
- 6Inspect and repair irrigation systems before the winter rainy season — while you won't need irrigation during wet months on windward sides, leeward properties still need functioning systems
December - February
Winter
- 1Reduce fertilization to one light application in January (0.25 to 0.5 lb N per 1,000 sq ft) — grass growth slows but doesn't stop in Hawaii's winter, and some nutrition is still needed
- 2On windward sides, watch for standing water and poor drainage during heavy winter rains — if water pools on the lawn for more than 24 hours after rain, you have a drainage problem that needs addressing
- 3Monitor for brown patch and large patch fungal diseases, which are most active during Hawaii's cooler, wetter winter months when nighttime temperatures drop into the 60s and humidity peaks
- 4Continue mowing as needed, typically once per week — bermuda and zoysia slow down but don't go dormant in Hawaii's mild winters, so the mower never gets put away entirely
- 5This is the best time for major lawn renovation projects — soil work, grading corrections, and complete re-establishment are easier when growth rates are lowest and rain provides natural irrigation
- 6Treat for sedge weeds (nutsedge, kyllinga) which thrive in wet winter conditions — these are the most persistent weed challenges in Hawaiian lawns and require targeted herbicides specific to sedge species
Regional timing notes
Hawaii is not one planting zone
Use these regional notes to adjust the statewide window for elevation, soil, heat, irrigation pressure, and local grass type.
Oahu / Honolulu
Oahu is home to roughly 70 percent of Hawaii's population, and its diverse microclimates create radically different lawn care environments within a 30-mile radius. Honolulu's urban core and the leeward south shore — Waikiki, Kahala, Hawaii Kai — receive 17 to 25 inches of annual rainfall, full sun exposure, and moderate salt spray from the prevailing trade winds. This is classic dry-tropical bermudagrass territory. Cross the Ko'olau Range to the windward side — Kailua, Kaneohe, Laie — and rainfall jumps to 50 to 80 inches annually, humidity stays above 80 percent year-round, and shade from tropical trees creates conditions more suited to zoysiagrass or shade-tolerant warm-season blends. The North Shore from Haleiwa to Kahuku occupies a middle ground with moderate rainfall and excellent growing conditions. Central Oahu — Mililani, Wahiawa, Schofield — has the famous red oxisol soil at its thickest and deepest, with pH values as low as 4.5 that require significant lime amendment. The Ewa plain on the west side (Ewa Beach, Kapolei, Ko Olina) is the driest and hottest part of the island, with just 15 to 20 inches of rain and summer temperatures that regularly hit 92 degrees — bermudagrass thrives here but irrigation is mandatory.
- On windward Oahu (Kailua, Kaneohe), fungal pressure from high humidity is the primary lawn challenge — avoid evening watering entirely and apply preventive fungicide during extended wet periods
- Central Oahu's red oxisol soil needs lime to raise pH above 5.5 — apply 50 lbs of dolomitic lime per 1,000 sq ft annually and use a phosphorus-heavy starter fertilizer to overcome the soil's phosphorus-binding tendency
Maui
Maui's lawn care landscape is defined by Haleakala's dramatic rain shadow effect. The leeward west side — Kihei, Wailea, Lahaina, Kaanapali — receives just 10 to 15 inches of annual rainfall and bakes under intense tropical sun with summer temperatures reaching 90-plus degrees. This is Hawaii's driest resort coast, and lawns here demand irrigation systems and heat-tolerant bermudagrass or zoysiagrass. Cross to the windward side and Haiku receives 40 to 60 inches annually, while Hana on the far east coast gets 80-plus inches. Upcountry Maui — Kula, Pukalani, Makawao — sits at 1,500 to 4,000 feet on Haleakala's slopes with cooler temperatures (60s to low 80s), moderate rainfall, and some of the best lawn-growing conditions in the state. The soil varies from young volcanic cinder on the upper slopes to deep red laterite in central Maui's former sugarcane fields. Maui's north shore communities (Paia, Spreckelsville) deal with persistent trade wind salt spray that demands salt-tolerant grass species. Water availability on Maui has been a contentious issue since the closure of the last sugar plantation, and irrigation water costs make drought-tolerant landscaping increasingly attractive.
- In Kihei and Wailea, irrigation is non-negotiable — bermudagrass needs 1 to 1.5 inches per week and rainfall provides almost none of it, so budget for significant water costs year-round
- Upcountry Maui (Kula, Pukalani) is cool enough at elevation that zoysiagrass outperforms bermuda — the slower growth rate is actually an advantage, reducing mowing frequency at altitude where conditions are milder
Big Island / Hawaii Island
The Big Island is a lawn care laboratory spanning 8 of the world's 13 climate zones on a single island. The Kona coast on the west side receives 10 to 25 inches of annual rainfall depending on elevation, with young volcanic soil that ranges from raw lava rock to thin pockets of mineral soil between flows — homeowners in Kailua-Kona and Waikoloa may need to import soil and create planting beds on top of bare pahoehoe or aa lava. The Kohala coast resort areas (Mauna Lani, Waikoloa, Mauna Kea) maintain emerald-green bermuda and seashore paspalum lawns that exist only through intensive irrigation and maintenance programs. Cross to the Hilo side and annual rainfall exceeds 130 inches — Hilo is one of the wettest cities in the United States, and the challenge isn't growing grass but preventing it from drowning, developing fungal disease, or being overtaken by moss. Waimea (Kamuela) at 2,700 feet in the saddle between Mauna Kea and Kohala sits in a unique cool, misty climate zone that can grow both warm-season and some cool-season grasses. The Big Island's active volcanic heritage means soil age and composition change dramatically over short distances — properties in Kona subdivisions built on 19th-century lava flows have fundamentally different soil than those on 10,000-year-old flows just miles away.
- In Kona and Waikoloa, soil may be thin or nonexistent over lava rock — importing 6 to 12 inches of topsoil or cinder mix and building raised lawn areas is often the only option for establishing turf
- In Hilo, drainage is the number one priority — the 130-plus inches of annual rain means standing water and waterlogged soil are constant threats, so ensure proper grading and consider French drains around lawn areas
Kauai
Kauai, the Garden Isle, is Hawaii's wettest major island and presents unique challenges for lawn care. Mount Waialeale in the island's interior averages 400-plus inches of rainfall annually, making it one of the wettest spots on earth. Even the populated coastal areas receive significant moisture: Lihue averages 40 inches, Kapaa gets 50, and the north shore town of Hanalei receives 85 inches. Only Poipu on the dry south shore resembles the leeward Maui or Oahu conditions, with 30 to 35 inches of rain and reliable sunshine. Kauai's soils are among the oldest in the island chain (approximately 5 million years old), deeply weathered into red-orange laterite that's highly acidic (pH 4.5 to 5.5) and almost devoid of available phosphorus due to iron-oxide binding. The north shore's Princeville community, perched on sea cliffs above Hanalei Bay, deals with constant trade wind salt spray, heavy rainfall, and sloped terrain that makes lawn establishment and maintenance exceptionally challenging. Kauai's relatively small population and strong environmental ethic mean chemical lawn treatments are viewed with more skepticism here than on other islands — many homeowners opt for organic approaches out of concern for reef health.
- Kauai's acidic laterite soil needs regular liming — apply dolomitic lime at 50 to 75 lbs per 1,000 sq ft annually, split between spring and fall, to maintain pH above 5.5 for healthy grass growth
- On the north shore (Hanalei, Princeville), choose zoysiagrass over bermuda — zoysia's density helps resist moss invasion in the wet, shaded conditions that bermuda struggles with
Next decision
Pick seed after the window is real
Once the timing works, move to the Hawaii seed guide for varieties matched to zones, soil, water pressure, and the grass type that fits your lawn.