Yes, you shouldn't have more than one watermelon seedling in that cup and probably no more than three in the little tub. But the real question is why you are trying to grow them so early in the season. When is your last frost date? Mine is around April 30. I wouldn't put watermelon seedlings outdoors until May 21-31 here. Watermelon really doesn't like its roots disturbed, so most advice is to direct seed them in the ground when your soil temperature is 65-70 F and over night lows are above 55-60. I do plant my seedlings indoors in early May in quart size containers and try to get them in the ground when they have no more than one set of true leaves. Your seedlings look very leggy and likely to be weak or dead by time you can get them outdoors. If you are going to grow them indoors, they need a lot more light. A sunny window won't do.

I start mine early in pots...one to a pot. It works MUCH better for me that way....than inground seeding so that I get some July watermelons It isn't a problem to transplant them. I let them grow about 21 days ideally. The early ones get plastic cloches for a few days. I have my early ones coming up now....to get some July melons. I like watermelons in hot weather...not so much in cool weather.

For myself, I start melons in their individual 3" pots. I plant 3 or 4 seeds to assure a really nice 'saver'. I do not plant them touching each other so that if I desire, I can move out one to another pot while still small.....somewhere between the 2 sizes you have. They transplant nicely if you dig them out with a tablespoon with sufficient 'soil' and if very hot, shade them that day.

I,never leave more than one plant in a pot.

This post was edited by wayne_5 on Tue, Apr 22, 14 at 11:07

Rookie mistake i guess. And our last frost is mid may. But do u think i could still have moderste success with these?

I agree with Wayne_5's method. With a last frost day in mid-May, you could put yours out around June 1. I suggest you start over by planting new seeds 3-4 to a cup around May 1. As he said, it's best if they are no more than three or four weeks old when you plant them outside. Before putting them outside, use scissors to cut all but one of the seedlings out of each cup leaving the healthiest one. Can you give them more light? They need to be very close to a sunny window, and they need sun all day. If you have fluorescent lights, you can grow them one or two inches under the lights and give them 16 hours of light a day.

We all make rookie mistakes. That's how we learn. Don't get discouraged. In my many years of growing plants I've probably killed many more than I was able to brag about.