I got some dill seeds off one of those Triscuit boxes. They started off really well and are still putting up new stems. The problems is that the older stems and leaves are turning gray and the tips of the leaves a brownish yellow.

The container is about 6"x6" and has three plants. The box came with about 10 seeds and said to use an 8 inch container. I figured it was decent spacing. They are in peat moss mixed with perlite and some sand for drainage. They are under a 4 bulb T-5 grow light. I water when the soil starts to dry out and fertilize only occasionally with an 8-4-4 liquid.

Here is a photo. The color variation looks like a lighting issue, but it's actually how the plant looks.