When to Plant Cauliflower in Honolulu, Hawaii (96821)

Location

Honolulu, Hawaii

ZIP Code

96821

USDA Zone

12b

Last Frost

Thursday, January 1, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Thursday, November 20, 2025

Transplant Outdoors

Thursday, January 1, 2026

Based on last frost Thursday, January 1, 2026 · Zone 12b

Pro tip: Start Cauliflower seeds indoors 6 weeks before your last frost date, then transplant outdoors around Thursday, January 1, 2026.

Add to Calendar (.ics)

🌿 Plant Details

Scientific Name Brassica oleracea var. botrytis

Days to Maturity 75 days

Mature Height 18-24"

Spread 24"

Type Head

Fruit Size Medium (6-8 inch head)

☀️ Growing Requirements

☀️

Sun

Full Sun (6 hours)

💧

Water

Regular (1-1.5 inches/week)

↔️

Spacing

18" apart

🌱

Planting Depth

0.5" deep

Seeds typically germinate in 4-10 days

Ready to Plant Cauliflower in Honolulu?

Get your seeds now so they're ready by Thursday, November 20, 2025.

🛒 Buy on Amazon 🌿 True Leaf Market

* Affiliate links — we may earn a small commission at no extra cost to you.

🤝 Good Companions

BeetCeleryBeanOnion

⚠️ Avoid Planting Near

StrawberryTomato

🤝

Full Companion Planting Guide for Cauliflower

See which plants help Cauliflower thrive, which to keep away, and raised bed layout tips →

🛠️ Supplies You'll Need

🌱 Seed Starting Trays 🪴 Seed Starting Mix 💡 Grow Lights 🌡️ Heat Mat 🪵 Raised Garden Bed 🌍 Vegetable Garden Soil 🛠️ Hand Trowel Set 🚿 Watering Can

* Affiliate links — we may earn a small commission at no extra cost to you.

Common Cauliflower Varieties

Popular cultivars to look for at your local nursery or seed supplier.

Snowball Y Improved

white 68d

Classic white cauliflower with dense, tight curds; reliable and widely adapted.

Cheddar

colored 68d

Orange-headed variety with a mild, buttery flavor and high beta-carotene content.

Graffiti

colored 80d

Brilliant purple cauliflower that holds its color when roasted; slightly nutty flavor.

Romanesco

specialty 80d

Lime-green logarithmic spirals with a mild, nutty taste; equally vegetable and art piece.

🌾 Seed Saving Guide

🔴 Difficult

✅ Open-pollinated — seeds grow true to parent

When to Harvest Seed

Allow head to bloom fully after the eating stage. Harvest seed pods when dry and tan.

Processing

Thresh dried seed stalks, winnow seeds from chaff.

Seed Viability

Up to 5 years when stored cool, dark, and dry.

Pro Tip

B. oleracea — crosses with all other oleracea cole crops. Very difficult to keep pure at home scale.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 14 plants of Cauliflower. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Cauliflower in Honolulu, Hawaii? +

In Honolulu (Zone 12b), start Cauliflower seeds indoors around Thursday, November 20, 2025 and transplant outdoors around Thursday, January 1, 2026.

What is the last frost date for Honolulu, Hawaii? +

The average last spring frost date for Honolulu, Hawaii (ZIP 96821) is around Thursday, January 1, 2026. This is based on NOAA climate normals for USDA Zone 12b.

How long does Cauliflower take to grow? +

Cauliflower typically matures in about 75 days from transplanting. In Honolulu, that means you can expect harvest around Thursday, January 1, 2026 plus 75 days.

Should I start Cauliflower indoors or direct sow in Hawaii? +

Cauliflower should be started indoors 6 weeks before your last frost date. In Honolulu, that means starting around Thursday, November 20, 2025.

📚 More Cauliflower Planting Guides

🗺️

Cauliflower in Hawaii

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 12b Cauliflower Guide

All cities in your zone · Avg dates

→

Other Plants for Honolulu

Blackberry Blueberry Raspberry Strawberry Basil Chamomile Chives Cilantro Dill Lavender Lemon Balm Marjoram Mint Oregano Parsley Rosemary Sage Tarragon Thyme Acorn Squash Artichoke Arugula Asparagus Beefsteak Tomato Beet Bell Pepper Bok Choy Broccoli Brussels Sprout Butternut Squash Cabbage Cantaloupe Carrot Cayenne Pepper Celery Cherry Tomato Chili Pepper Collard Green Common Bean Cucumber Eggplant Endive Fennel Garlic Grape Tomato Green Bean Habanero Pepper Head Lettuce Heirloom Tomato Honeydew Melon Jalapeño Pepper Kale Kohlrabi Leaf Lettuce Leek Lima Bean Mustard Okra Onion Parsnip Pea Poblano Pepper Pole Pea Potato Pumpkin Radicchio Radish Rhubarb Roma Tomato Rutabaga Serrano Pepper Shallot Snap Pea Snow Pea Spaghetti Squash Spinach Squash Sweet Corn Sweet Potato Swiss Chard Tomato Turnip Watermelon Zucchini Sunflower Marigold Zinnia Nasturtium Cosmos Echinacea (Coneflower) Petunia Black-eyed Susan Apple Tree Pear Tree Peach Tree Plum Tree Sweet Cherry Tree Lemon Tree Borage Lemongrass Ginger Stevia Tomatillo Edamame Fava Bean Mâche Mizuna Sorrel Shishito Pepper Banana Pepper Watermelon Radish Napa Cabbage Popcorn Broccoli Raab Catnip Valerian Lemon Verbena Bee Balm Anise Lovage Chervil Summer Savory Dahlia Snapdragon Pansy Sweet Pea Morning Glory Hollyhock Larkspur Bachelor Button Columbine Impatiens Salvia (Annual) Sweet Alyssum Celosia Lupine Verbena Elderberry Grape Vine Red Currant Gooseberry Serviceberry Fig Tree Avocado Tree Persimmon Tree Olive Tree

Growing Cauliflower in Zone 12b

Cauliflower (Brassica oleracea var. botrytis) is a popular garden vegetable. In Honolulu, Hawaii, which is in USDA Hardiness Zone 12b, you should start seeds indoors around Thursday, November 20, 2025.

Your average last frost date is Thursday, January 1, 2026. Plan to transplant your Cauliflower seedlings outdoors around Thursday, January 1, 2026, about 0 weeks after your last frost date.