North America Non-native Plant

Watermelon

Botanical name: Citrullus lanatus var. lanatus

USDA symbol: CILAL

Life cycle: annual

Habit: vine

Native status: Non-native, reproduces and persists in the wild in the lower 48 states âš˜ Non-native, reproduces and persists in the wild in the U.S. Virgin Islands  

Synonyms: Citrullus citrullus (L.) Karst., nom. inval. (CICI2)  âš˜  Citrullus colocynthis (L.) Schrad. var. lanatus (Thunb.) Matsum. & Nakai (CICOL2)  âš˜  Citrullus vulgaris Schrad. (CIVU3)  âš˜  Colocynthis citrullus (L.) Kuntze (COCI2)  âš˜  Cucubertia citrullus L. (CUCI)  âš˜  Momordica lanata Thunb. (MOLA7)   

Growing Watermelon: The Sweet Summer Treat That’s Worth the Garden Space Few things say summer quite like biting into a juicy, sweet watermelon on a hot day. While you might think of watermelons as something you pick up at the grocery store, growing your own Citrullus lanatus var. lanatus can ...

Growing Watermelon: The Sweet Summer Treat That’s Worth the Garden Space

Few things say summer quite like biting into a juicy, sweet watermelon on a hot day. While you might think of watermelons as something you pick up at the grocery store, growing your own Citrullus lanatus var. lanatus can be one of the most rewarding (and space-consuming) adventures in your garden.

What Exactly is Watermelon?

Watermelon is an annual forb herb – basically a non-woody plant that completes its entire life cycle in one growing season. Don’t let the term herb fool you though; this sprawling vine can take over significant portions of your garden with its large, lobed leaves and trailing stems that can stretch 10 feet or more in every direction.

Originally hailing from Africa’s Kalahari Desert region, watermelon is a non-native species that has been introduced across much of the United States. Today, you can find it growing (either cultivated or naturalized) in states from coast to coast, including Alabama, Arizona, Arkansas, California, and many others across the lower 48 states, plus the U.S. Virgin Islands.

Should You Grow Watermelon in Your Garden?

The answer depends largely on your space, patience, and summer length. Here’s what you need to consider:

The Sweet Rewards

  • Incredible flavor: Nothing beats a homegrown watermelon for sweetness and that perfect texture
  • Pollinator magnet: The yellow flowers attract bees and other beneficial insects to your garden
  • Impressive yields: One plant can produce multiple large fruits
  • Natural ground cover: The sprawling vines can help suppress weeds in large areas

The Challenges

  • Space hogs: Each plant needs 6-12 feet in all directions
  • Long growing season: Requires 90-100+ frost-free days
  • Water demands: Needs consistent moisture, especially during fruit development
  • Heat lovers: Won’t thrive in cool, short summers

Perfect Growing Conditions

Watermelons are sun worshippers that need specific conditions to thrive:

  • Full sun: At least 6-8 hours of direct sunlight daily
  • Warm temperatures: Soil should be 70°F or warmer before planting
  • Well-draining, fertile soil: Rich, loamy soil with good drainage prevents root rot
  • Consistent moisture: About 1-2 inches of water per week, more during fruit development
  • Space to roam: Allow plenty of room for vines to spread

Watermelons can be grown as annuals in USDA hardiness zones 3-11, though they perform best in zones 4-10 where summers are long and warm.

Planting and Care Tips

Getting Started

Start watermelon seeds indoors 2-4 weeks before your last frost date, or direct sow outdoors once soil temperatures consistently reach 70°F. Plant seeds about 1 inch deep and space plants 6-12 feet apart – yes, they really need that much room!

Ongoing Care

  • Water deeply but infrequently: Encourage deep root growth with thorough, weekly waterings
  • Mulch around plants: Helps retain moisture and suppress weeds
  • Support developing fruits: Place cardboard or straw under large fruits to prevent ground rot
  • Reduce watering near harvest: Stop watering 1-2 weeks before harvest to concentrate sugars

Garden Design Considerations

Watermelons work best in:

  • Large vegetable gardens with plenty of open space
  • Agricultural or farm settings
  • Dedicated melon patches
  • Areas where you want seasonal ground cover

They’re not ideal for small urban gardens, container growing, or formal landscape designs due to their sprawling nature.

A Note on Native Alternatives

While watermelon isn’t native to North America, it’s not considered invasive either. However, if you’re interested in supporting native ecosystems, consider exploring native alternatives like wild gourds (Cucurbita species) or native ground cherries (Physalis species) that can provide interesting fruits while supporting local wildlife.

The Bottom Line

Growing watermelon is a commitment – to space, time, and consistent care. But if you have a large garden, live in an area with long, hot summers, and dream of harvesting your own sweet, juicy melons, it’s absolutely worth the effort. Just make sure you have a plan for all those watermelons come harvest time – you might be surprised by how productive these sprawling vines can be!

Watermelon

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Dilleniidae

Order

Violales

Family

Cucurbitaceae Juss. - Cucumber family

Genus

Citrullus Schrad. - watermelon

Species

Citrullus lanatus (Thunb.) Matsum. & Nakai - watermelon

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA