It is important to harvest watermelons when they are ripe and not before! Because the ripeness of the watermelon is hidden under the outer skin as a bright, rich, watery flesh inside, the only sure way to know the quality of the flesh and its ripeness is to crack it open. But, of course, a cracked melon is unsellable.
The timing and efficiency of harvest are also important. You do not want to harvest unripe melons, of course. You also want to focus your harvest so all melons that need picking are picked at the same time.
There are, thankfully, many tricks and tips used to help growers understand when a watermelon is ripe and ready for picking. But which technique is most accurate? Here we will explore some of the methods discussed and focus on the best means to manage watermelon harvest.
People will tell you that a melon is ripe when it sounds hollow when thumped with your knuckles. They will also say to look for the big yellow moon spot on the underside of the melon where it lies on the ground. Some will tell you to wait for the green outer rind to become deep in color and for the lines between the lighter and dark greens to be very distinct.
I have seen lists of as many as 12 ways to tell when a melon is ripe! But the three best methods, which make the most sense, are actually fairly simple.
1. Watch the Calendar
First, choose a melon and make note of the days to maturity (DTM) for the variety.
For a melon, though, this DTM sometimes indicates days from transplanting in the field. So make sure you understand the difference between transplanting and direct seeding.
2. Mind the DTM
Second, follow good cultural practices for watermelon production in your region. I grow melons how most do in the northeastern and northern USA and all of Canada, which includes:
- growing from transplant
- planting into loose, fertile soil
- using weed barrier or black mulches to increase heat
- often covering with a mini greenhouse or row cover for a few weeks in spring.
Done as such, a DTM will be very accurate.
Third, grow the same varieties every year. This way you will get good at understanding how the melons mature and seeing their ripeness.
Remember those 12 signs of ripeness! They are all, in fact, real. But these signs can be very confusing if you grow many different melons, never repeating. So make sure to stick to some varieties.
4. Ripen Together
Fourth, commercial growers should choose varieties that tend to ripen together. This way, you can harvest the entire plot at once.
This also means that, if you check a few melons by cutting them open and they are perfect, you can reasonably assume the rest of the patch is also perfectly ripe.
Note, most of the hints above actually just tell you to know your melon variety and grow it properly. These are really the best indicators of ripeness.
If you know the melon is 75 days from transplanting into the field, and you plant it into the field on May 24th—into rich soil with a weed barrier mulch—and water to properly all season, then it is very reasonable to assume the melon will mature around august 10-15th. And then you can reasonably use any means of assessing ripeness to help assure you the melon patch is ready.
But what is the best indicator on the actual melon’s ripeness, other than cutting one open? Well, let me add one more trick to your list.
I used to grow about 1500 to 3000 melons each summer for my CSA program and farmers markets. And over the years, I found that the most reliable way of telling a melon’s ripeness is to look at the point where the stalk comes off the melon itself and connects to the main vine of the plant.
At this junction point of melon stalk and main vine, there is usually a little leaf and a little curly tendril. When this leaf and/or tendril is dry (or drying), the melon is perfect. If 50 percent of the patch shows signs of this, then the whole patch is ready. Harvest away!