how many days to I need to produce seeds from various crops?

I really wanted to grow all my own seed crops this year as I start making landraces. However, I've gotten behind on planting some things. Nobody online talks about how long it takes to produce seeds, just how to get a vegetable to edible maturity.

The crops I'm wondering about are lettuce, spinach, radish, and asian greens. I wanted to select them for heat tolerance by starting them in hot weather and saving the last ten percent to bolt. However, will I have enough time to mature seed by frost? I can get an early frost by September 10th, and average is October 10th. I might be able to cover things a bit.

On the other hand, I'm going to plant the same things in early September, leave the little plants out all winter, and save seed from whatever survives till spring. That way I will have a cold hardy and a heat tolerant landrace.

Gilbert Fritz wrote:The crops I'm wondering about are lettuce, spinach, radish, and asian greens.

Add about 4 to 6 weeks to the normal harvest time... If they are maturing in cool fall weather, then add 2 to 3 more weeks.

My bok choi seed is just drying down now from plants that were started last fall. The spring planted plants are only about a week behind.

The lettuce that was planted in early April is just starting to flower. The March planted lettuce is in full bloom.

Spinach is just starting to dry down from the November and March plantings. The April planting died without producing seeds.

Thanks, that is really helpful. Advice from the seed master!