Thursday, September 16, 2010

When are watermelons ready?

I never used to be a fan of growing watermelons in northern climates. Years ago available varieties never reached maturity and tasted bland or green. Newer short season watermelons have changed all that. Varieties such as ‘Sugar Baby’ (75 days), ‘Shiny Boy’ (75 days), ‘Yellow Doll' (76 days), ‘Blacktail Mountain’ (70 days) and others have a reasonable shot at maturing in our short growing season. They should be transplanted like many warm-season vegetables so seed your own indoors in spring or purchase transplants.

A frequent question I receive is how to tell when watermelons are ripe. You can gently roll the melon over to check for a yellow groundspot. Another clue is to look for the curled tendril below the vine attachment. Green tendrils indicate a green melon while a shriveled, brown tendril indicates maturity.

Then there is the sounding method. A knuckle tap that yields a dull sound indicates under-ripe. If it sounds hollow, the watermelon is ripe for eating. A soft sound indicates over-ripe. This method also works in the produce market.

Tapping knuckles takes on a whole new meaning for cool vegetable gardeners.

Photo credit: Watermelon on vine – Carl Wilson, ‘Shiny Boy’ watermelon – 2010 All America Selections winner.


  1. Great tips!

    Thank you!

    My Uncle can tell a ripe watermelon by knuckle tapping, we haven't figured it out yet!

    I'd love to be able to grow watermelons, a cousin grew them by a mini-lake (that acts like heat collector and 'mirror' to reflect sunrays) in a terrace-hill with lots of sunlight (south-facing), not sure what sort he had - hope these can be found locally! I wonder if our climates are similar? Probably depends on the weather and the summer too?

  2. Is there any way you can convert those "Days to Maturity" into GDD (Growing Degree Days)? I calculated that around here i might have about 900 GDD with a base of 60 degrees F. From what i've read.. traditional watermelon's require 2000 GDD.