esobofh,

Yes, you can let them dry up. However, if you have just a few plants and don't want to chance losing the seed to birds, etc., you can cut the plants when the pods are "yellowish" and the seed inside is getting some brown or tan coloring. Then hang the plants in a shaded, dry area and allow to dry there.

Radish pods stay together well. Cabbage and broccoli will get dry enough that they may split open eventually so those would be best hung (or laid on screening)where you can easily get the seed if they do. Chinese cabbages, Chinese mustards have very fragile pods when completely dried.

Weed

Excellent info.. thanks Weed!

To Weed,
I have 2 radish plants so far that just got their flowers. My question is, I know that I need to give them time to pollinate, but for how long do I let them stay in the ground? I live outside Tucson and where I live it is very windy most days, but very hot! So, I'm worried that the wind will carry the seeds before I have a chance to harvest. Can you give me some clues?
This is the first year we are going to harvest our own seeds for next year.
P.S. These radishes are from store bought packages, hybrid, and will we even get seeds?
Thanks for your time,
Jenny T.