Nettles have two separate flowering plants: male and female - only the female plants produce seeds.
Stinging nettle (Urtica dioica) is a perennial* plant that flowers from late summer into autumn.
*Perennial is a plant that lives more than two years. The term is often used to differentiate a plant from shorter-lived annuals and biennials. (https://en.wikipedia.org/wiki/Perennial_plant)
The males produce small clusters of flowers to produce pollen to fertilise the female plants which in turn then produce the seeds.
When they close they looks like (some people say) a tiny bishop hat.
The seed harvest comes from the female plants.
Seeds are best gathered when green and fresh. You can eat them raw! They have lots of amazing beneficial health properties that are coming from the nettle plant itself.
When you pick them, use them quickly so they don't loose their beneficial oil properties.
Once brown and dry, the seeds of not much use.
How to forage nettle seeds
You will need:
Wear gloves to pick the nettle seeds. Use scissors to cut the top stems with seeds on. Tie them together, place them upside-down in the bag, hold the stems and bag by the 'neck' and give a good shake. The seeds should come off the stem easily.
They are also perfect to add raw to smoothies, porridge or salad.
So go and get foraging those amazing nettle seeds.