When to Plant Watermelon in Onslow, Iowa (52321)
Location
Onslow, Iowa
ZIP Code
52321
USDA Zone
5a
Last Frost
Sunday, May 10, 2026
📅 Planting Calendar
Start Seeds Indoors Sunday, April 12, 2026
Transplant Outdoors Sunday, May 24, 2026
Pro Tip: Start Watermelon seeds indoors 4 weeks before your last frost date for best results.
🌿 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
🤝 Good Companions
CornSunflowerMarigold
⚠️ Avoid Planting Near
Potato
Other Plants for Onslow
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 Brussel 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
Growing Watermelon in Zone 5a
Watermelon (Citrullus lanatus) is a popular garden vegetable. In Onslow, Iowa, which is in USDA Hardiness Zone 5a, you should start seeds indoors around Sunday, April 12, 2026.
Your average last frost date is Sunday, May 10, 2026. Plan to transplant your Watermelon seedlings outdoors around Sunday, May 24, 2026, about 2 weeks after your last frost date.