When to Plant Watermelon in Bryn Mawr, California (92318)

Location

Bryn Mawr, California

ZIP Code

92318

USDA Zone

Last Frost

Tuesday, February 10, 2026

📅 Planting Calendar

Start Seeds Indoors Tuesday, January 13, 2026

Transplant Outdoors Tuesday, February 24, 2026

Pro Tip: Start Watermelon seeds indoors 4 weeks before your last frost date, then transplant outdoors around Tuesday, February 24, 2026.

🌿 Plant Details

Scientific Name Citrullus lanatus

Days to Maturity 80 days

Mature Height 12-24"

Spread 72"

Type Vine

Fruit Size Large (10-30 lbs)

☀️ Growing Requirements

☀️

Sun

Full Sun (8+ hours)

💧

Water

Regular (1-2 inches/week)

↔️

Spacing

72" apart

🌱

Planting Depth

1" deep

Seeds typically germinate in 4-12 days

Ready to Plant Watermelon in Bryn Mawr?

Get your seeds now so they're ready by Tuesday, January 13, 2026.

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🤝 Good Companions

CornSunflowerMarigold

⚠️ Avoid Planting Near

Potato

Other Plants for Bryn Mawr

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 Cauliflower 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 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 Watermelon in Zone 9b

Watermelon (Citrullus lanatus) is a popular garden vegetable. In Bryn Mawr, California, which is in USDA Hardiness Zone 9b, you should start seeds indoors around Tuesday, January 13, 2026.

Your average last frost date is Tuesday, February 10, 2026. Plan to transplant your Watermelon seedlings outdoors around Tuesday, February 24, 2026, about 2 weeks after your last frost date.