I started some giga white alyssum seeds at the beginning of March in our basement. I have flourescent lighting on them about 4 inches away and a fan circulating the air. The temperature is about 73 degrees during the day and may go down to 65 at night.
They were looking good and have grown to about 1 inch in height until about a week ago. Now I'm getting some yellow leaves and some dark spots on some leaves before they start to wither. Some, not too many, have turned white.
I water them every day thoroughly and I don't see any pests on the leaves. I have noticed a couple small black fly-like insects flying around. Only a couple and not every time I check on my plants. All the other seedling plants are fine.
Any ideas on what could be the problem? Thanks in advance for any advice