tessa:

If you are talking about watermelons that have achieved the size of softballs now, or in the recent past, that is way too late for zone 5 Wisconsin. You need to have your melons forming in mid-July, at the latest, so that they can be full-size and ripening out now.

You will have to start your melons earlier, either by direct-seeding or by starting early plants, and grow them on large sheets of black plastic mulch to heat up the soil and get the vines and fruit going earlier. Black plastic can make a tremendous difference in how melons perform, since melons do not really grow until soil temperatures reach about 75 degrees, and even warmer is better. You don't specify the sunlight situation of your melon vines, but if they are not receiving full sun that can also seriously affect their performance. Healthy vines are fine, but you need to have them a lot sooner in the season.

Pollination could be an issue if you are trying to grow some type of seedless melon that requires a companion pollinator. Try Sugar Baby before you try any other variety of melon. They are relatively early, easy to pollinate, and taste great. Melons that reach softball size have probably been sufficiently pollinated, so I don't think that is the problem. The heavy rains you have recently had in Wisconsin may have played a role, since melons prefer dry weather during the ripening period to reduce rotting and splitting. Another reason to start them earlier so they are out of the field before fall rains begin.

Don Yellman, Great Falls, VA

Hello, again,

I started them waaaay early this year after last year I had several lovelies that didn't quite ripen before the frost. This year they were spread out for at least a six foot radius by the end of June and the first fruit I saw do the grow and rot was in July and it has been ongoing since then although none of them have gotten larger than golf balls after the first ones went. I suspect in the general sense the obscene amount of rain (over 5 times our norm for August) is a partial contributor.

They have absolutely full sun so I wouldn't think that was the issue. Maybe I need to add the plastic... I'm not sure of the variety, I'll have to dig for the envelope. I'll look into getting some sugar baby seeds for next spring.

I just thought it was particularly odd since my sugar melons seem to be doing fine.

Two years ago I had a very healthy crop (same envelope of seeds) so that's part of why I'm baffled also.

Thanks for the help!

Sincerely,
Teresa

tessa-

I'm near La Crosse. I have a sugar baby vine that has had 2 around 7lb melons that have stayed the same size for about 6 weeks. The other vine i have (sugar baby too) had 1 5pound fruit (vine was very small) and that watermelon tasted fine (nothing great) but wasn't watery?, nice and red, not many seeds. We have had 20 inches of rain here since June 1. I think you should try a different variety next year. I had a vine in the tomato patch that had a fruit the size of a football that rotted out (i just let it be...tomatoes have gone DOWNHILL from all this rain...crack city).

I'm going with a variety called 420 that another member had good luck with. If not, stick with sugar babies. They seem to have no problems for me.