When to Plant Melons: Timing, Spacing and Companions for Cantaloupe and Watermelon

Cantaloupes (muskmelons), honeydews and watermelons all come from warm climates and need a long, hot season. Plant into cold soil and seeds rot or seedlings sit still for weeks; plant too late and the fruit runs out of summer before it ripens. Getting the window right is most of the battle.

Step 1: wait for warm soil, not just the frost date

Frost is only the first hurdle. University of Minnesota Extension says to wait until the top 2 inches of soil are at least 65°F, and notes melon seeds germinate best between 70 and 90°F. Iowa State puts the planting point at 60 to 70°F, and University of Maryland Extension lists melons among the crops that need soil of at least 60°F. A cheap soil thermometer, read in the morning, takes the guesswork out. In practice that usually means planting 1 to 3 weeks after the average last frost; Iowa State plants in mid-May in central Iowa.

Step 2: planting dates by last frost

The table below assumes you plant out or direct-sow 1 to 3 weeks after your last frost, and start seeds indoors 3 to 4 weeks before planting out. Shift later in a cold, wet spring.

Our planting calendar does the same math for other crops from your own frost date. Iowa State gives June 20 as the last practical sowing date for early varieties in Iowa. Elsewhere, count back from your first fall frost: add the days to maturity on the seed packet to a couple of weeks of slack, and make sure the vines will have that much warm weather left.

Step 3: seeds or transplants?

• Direct sowing is simplest. Iowa State plants hills of 4 or 5 seeds about 1 inch deep and thins to the 2 or 3 strongest plants once they have a true leaf or two.
• Transplants buy time in short-season areas. UMD notes transplanted melons can be harvested as much as four weeks earlier. Melons resent root disturbance, so start them in plantable pots such as peat pots, sow 3 or 4 seeds per pot and keep the best two, and set them out young, at 1 to 2 true leaves (Iowa State) or 2 to 3 (UMN), after hardening them off for a few days.
• Warm the bed. UMN and UMD both say black plastic mulch helps melons grow earlier and larger crops, and row covers or low tunnels protect young plants. Take covers off once flowers open so bees can reach them.

Step 4: sun, soil and spacing

Short on room? Bush varieties fit smaller beds, and small-fruited melons can climb a sturdy trellis if each fruit gets a sling. See vertical vegetable gardening.

What to plant with melons

Extension companion tables rarely list melons on their own, so the best guide is their family. Melons are cucurbits, like cucumbers, squash and pumpkins, and share their pests and their needs. Cucumbers follow the same warm-soil rule; see when to plant cucumbers.

• Good neighbors: corn, which extension tables pair with cucumbers, squash and pumpkins; radishes, often listed with cucumbers; and flowers such as marigolds and nasturtiums, listed with squash and pumpkins, which also draw pollinators to the patch.
• Keep apart: potatoes, which several sources list as poor neighbors for cucurbits; and other cucurbits planted in one big block, which makes it easier for cucumber beetles and squash bugs to build up.
• Rotate: Iowa State suggests not growing cucurbits in the same spot more often than every 3 to 4 years. See what to plant with cucumbers and what to plant with pumpkins for the relatives.

Watering and care

Melons need steady moisture but hate wet feet. Iowa State suggests 1 to 2 inches of water every 7 to 10 days in dry weather, ideally by drip or soaker hose in the morning to keep leaves dry, and about half as much per watering as the fruit nears ripeness. UMN also suggests easing back near harvest; too much water as melons ripen can make them split. Keep weeds down while vines are small, then let the leaves shade the soil.

When melons are ripe

• Cantaloupe (muskmelon): the netting fills out, the skin turns from green to tan or yellow, and the melon slips off the vine with light pressure, called full slip.
• Honeydew: doesn't slip. Look for a creamy or yellowish rind and a slightly waxy feel, and cut it with a short piece of stem.
• Watermelon: doesn't slip either. UMN points to the curly tendril nearest the fruit turning brown and dry, and the spot where the melon rests on the ground turning from white to yellow.

Frequently asked questions

When should I plant melons?

After your last spring frost, once the soil is at least 60 to 65°F. For most gardens that is about 1 to 3 weeks after the average last frost date; Iowa State plants in mid-May in central Iowa.

Can I start melon seeds indoors?

Yes. Start them about 3 to 4 weeks before you plan to plant out, in plantable pots such as peat pots, because melons dislike root disturbance. Set them out young, at one to three true leaves, after hardening off.

How late can I plant melons?

Count back from your first fall frost using the days to maturity on the packet plus a little slack. Iowa State gives June 20 as the last practical sowing date for early varieties in Iowa.

What should I plant with melons?

Melons are cucurbits, so they follow their relatives: corn, radishes and flowers such as marigolds and nasturtiums are commonly paired with them. Keep potatoes away and avoid planting melons where any cucurbit grew in the last 3 to 4 years.

How far apart should I plant melons?

Iowa State spaces cantaloupe hills 1½ to 2 feet apart in rows 5 to 6 feet apart, and watermelon hills 2 to 3 feet apart in rows 6 to 8 feet apart. Bush varieties need less room.

How do I know when a cantaloupe is ripe?

The netting fills out, the skin turns tan or yellow under the netting, and the fruit slips off the vine with light pressure. Watermelons don't slip; look for a brown, dry tendril nearest the fruit and a yellow ground spot.