Tedra Erikson Stanley performing the thumbnail test.
Mirlitons are typically ready to harvest when they reach approximately 8 ounces, although size and weight can vary. The most reliable method for testing for harvesting is the thumbnail test.
Start by pushing on the fruit skin with your thumbnail. If the fruit skin dents or even seeps a little moisture, the fruit is still immature and will be too watery. If it is firm and does not dent, you are ready to pick. The old growers used to say, “My mirlitons are hard now and ready to pick.”
See Tedra Stanley’s video on how to do the test here.
At the hard stage, they are also mature enough to sprout and or use as seed. But once they begin to sprout, they’re too tough to cook.