When to Plant Brussels Sprouts in Hawaii
Published: April 24, 2026
Hawaii gardeners in Zone 12a have essentially year-round growing for brussels sprout. Cool-season crops like brussels sprout are best planted in the cooler winter months (October through February) — summer heat prevents these plants from heading or forming a harvestable crop. This guide gives exact dates for Hawaii based on your local frost calendar.
Brussels Sprout Planting Dates for Hawaii
| Start seeds indoors | Year-round (avoid peak summer heat) |
| Last frost (average) | Frost-free |
| Transplant outdoors | Year-round (October–March is primary window) |
| Expect first harvest | 45–120 days after planting |
| Fall crop start | October |
| Fall harvest | January–March |
| First fall frost (average) | Frost-free |
⚠ Brussels sprouts are planted in midsummer for a fall harvest. Count back 90 days from your first fall frost to find the transplant date. Start seeds indoors 4–6 weeks before that date. Flavor improves after frost.
Growing Brussels Sprouts in Hawaii's Climate
Hawaii's tropical climate gives brussels sprout year-round potential, but not all months are equal. Wet season (May through October in most of Hawaii) brings disease pressure that can destroy a brussels sprout crop within days if fungal conditions align. Dry season (November through April) is the primary productive window.
Soil drainage matters more in tropical climates than almost anywhere else. Raised beds or heavily amended beds with 50% compost content drain rainfall quickly and keep brussels sprout roots oxygenated during heavy storms. Flat beds in native clay soil often fail the first wet season.
Common brussels sprout pests to watch for in Hawaii include Cabbage Worm and Aphid. The first line of defense is companion planting: Onion and Celery planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Brussels Sprout Garden Calendar for Hawaii
| Month | Task | Notes |
|---|---|---|
| January | First harvests | Early transplants reach harvest size |
| February | Main harvest month | Peak production month in tropical climate |
| March | Continue harvests | Last window for new plantings before wet season |
| April | Finish harvests | Wet season approaching — harvest ripe crops |
| May ← | Clear beds | Disease pressure rises with wet season; warm-season ornamentals now |
| June | — | |
| July | — | |
| August | — | |
| September | — | |
| October | Prime planting window opens | Direct sow or transplant brussels sprout; dry season begins |
| November | Main planting month | Peak planting window for best harvests |
| December | Continue successions | Plant every 2–3 weeks for staggered harvest |
Brussels Sprout Growing Tips for Hawaii Gardeners
- •Count back 90 days from first fall frost to find the transplant date — this is the most important Brussels sprout timing rule.
- •Pinch the top of each plant about a month before first frost — this channels energy into sprout formation.
- •Hawaii's tropical climate favors planting brussels sprout in dry season (October through April). Wet season plantings are destroyed by fungal disease within weeks.
- •Harvest sprouts from the bottom up as they reach 1-inch diameter; top sprouts finish last.
Companion Planting for Brussels Sprouts in Hawaii
In Hawaii's tropical climate, planting brussels sprout with Onion and Celery helps deter pests and improve soil. Avoid planting near Tomato and Strawberry, which inhibit brussels sprout growth through root chemistry or shared pest pressure. See the full brussels sprout companion planting guide for the complete list.
Brussels Sprouts Planting Dates by City in Hawaii
Top cities in Hawaii — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant brussels sprout in Hawaii?
In Hawaii (Zone 12a), start brussels sprout seeds indoors around Year-round (avoid peak summer heat) and transplant outdoors around Year-round (October–March is primary window) — 12 weeks after the state's average last frost of Frost-free.
What is the last frost date in Hawaii?
Hawaii's average last frost date is Frost-free in the state's most common Zone 12a. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow brussels sprout year-round in Hawaii?
Yes, Hawaii's frost-free climate supports year-round brussels sprout growing. October through March is the primary productive window; summer heat and wet-season fungal pressure limit what you can grow June through September.
What brussels sprout varieties grow best in Hawaii?
For Hawaii's Zone 12a, consult a local nursery or extension office for brussels-sprouts variety recommendations.
When do I start brussels sprout seeds indoors in Hawaii?
Start brussels sprout seeds indoors in Hawaii around Year-round (avoid peak summer heat), which is 5 weeks before the state's average last frost of Frost-free. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.