Hello! I am new to the forum. I know a but about plants but am learning
lots more all the time.

Can someone advise please? I have 2 beautiful Agapantha Plants whose
flowers have just turned to seed heads. Most are still green.

I would like to try and grow some more plants from seeds, (I understand
that it will take at least 3 years for the plants to flower).

My question is - can I use the green seeds or do I need to wait until
they have dried on the plant?

I haven't experimented with Agapanthus, but the safe thing to do is to
wait until the fruits have started to dry down on the plant, then remove
and plant the seed.

Since you probably have a number of fruits on the plant, you might want
to live slightly dangerously, and remove a fruit every other day or so,
open it gently, and immediately plant the seeds within. .

Seeds go through a series of phases of maturation... the embryo is
created (and quite often, that's viable if you want to try to grow it
much like a tissue-culture project!), the endosperm (storage tissue)
forms and matures, and finally, with both embryo and endosperm (or other
storage tissue in some seeds) completely physiologically mature, the
fruit starts drying down, readying the seeds for dispersal.

Sometimes (and this is highly species-dependent) you can shorten the
germination time for some seeds from months or weeks to a few days --
that's because the mechanisms that allow seeds to remain dormant for a
bit are usually added toward the end of the maturation phase. If you
catch the seeds at just the right age, when they've got enough storage
reserves to grow well, but before the dormancy factors are "added",
you can get seedlings up and growing quickly. May or may not
be worth your time to experiment, but it can be fun to do so.

Kay