I let my spinach seeds bolt so that I could get some seeds to replace the ones that I used this season. I have done some online research saying I need to cut the stems, hang them to dry, and then use a strainer to collect the seeds.

That's all well and good, but how do I know when the seeds are mature enough on the plant to cut the stalk in the first place? Right now most of mine have formed light green, flattened-ball shape seeds. I can try to take a picture tomorrow, but how do I know when they are ready or if they need more time on the stalk?

Also, if a stalk has turned a pale yellow-ish color, should I just pull it, or will it still set seed?

Personaly I wait untill the seed heads are almost dry on the plant then pull to finish. I don't think yours are ready.

Thank you for the input. Any idea how long they usually take?

I usually let them go to seed, and they drop some and I have a late fall crop from them, some germinate in the spring, and I have a really early crop then too.

Letting them reseed is a good idea, although I do want to save some to give to family or to have as backup. Will they actually turn brown on the stalk when they are ready?

I haven't saved spinach seeds, but I expect most seed stalks to look "very dead" before the seeds are fully ripe and dry.

The longer you can leave them "on the vine", the more likely they are to reach full maturity and viability.

Reasons to harvest earlier:

1. You expect constant rain that would rot the seeds before collecting.

2. The seeds are about to drop spontaneously and be lost. You can bag some stalks to catch the seeds, or just watch very closely and as soon as any seeds drop, harvest the brownest 2/3 of your plants. If you don;t have rain or heavy dew, set out boxes or trays or whatever to catch the first seeds to drop. Once you see any seeds in your trap, harvest several stalks or shake the stems - FULLY ripe and dry seeds will fall right out of some plants with just a shaking.

3. Birds or neighbors are likely to steal them before you can harvest them.

4. Gardener impatience. There's no cure for that, other than (perhaps) saving lots and lots and LOTS of seeds over many years. My theory is that, eventually, the obsession will fade or at least become more manageable. I hope you let me know if that ever happens for you!