I'm trying to save the seeds from a basil bush that grew really well for me. It bolted probably a month or two ago, but it seems that the seeds won't mature before the stem that the flowers are on dies!

What seems to happen is that as is expected bunch of flowers form on about a 3-5" section of stem. Then the flowers wilt as expected. But then, instead of the seeds forming and maturing in the seed-pod, the whole 3-5" section of stem starts wilting, and dies before the seeds have formed.

What could be causing this, and what could I do about it? I have saved basil seeds before and I'm not really doing anything different this time!

Thanks
Neilen