Hi, I'm somewhat new to indoor seed starting. I started seeing a problem two days ago with only a few of one variety of zinnias I'm growing. I have about 400 seeds of all types of flowers and veggies, and no problems else where except the pumpkins, but that's a separate post... The zinnia leaf tips are turning brown and curling up. I havent fertilized yet (30 day old plants with one big set of true leaves). I may have been overwatering the last few times. Help please!