When and how to harvest seeds from CROTON houseplant ?

My croton has started to grow this long seed thingy (??) .. at least I think it is seeds.
How do I harvest (and WHEN do I know the seeds are mature enough to harvest) ??
Also at what temperatures/conditions would I germinate the seeds ??

I am trying to upload a few pictures, too

While you are at it ... can you tell me why my croton has started to grow yellow leaves (it used to put out new growth which was light green and which turned dark green, but now it is yellow and only very slowly it is turning, but more to a redish color). ??
I recently moved this one from a window to growlights. Can this have anything to do with it ? (I also started using a new fertilizer with higher levels of nitrate..)

Here is a picture of the seed thingy growing from the growing tip (see: yellow leaves)

Here is a picture of the old(er) green leaves and the new strange yellow leaves
See .. the older yellow leaves are turning red by the ribs, but the inside portion of the leaves remain yellow..

Ok, here is an older picture of the light green new growth coming from the old leaves. This was how new growth used to look before the strange yellow leaves came out.
I wonder if it has anything to do with the change in light, or could it be related to setting seeds ?

I am so anxious to hear your responses. I can't believe no one has answered you. Do you think this would get more interest in the tropicals forum?

Gosh, that sure is pretty with the yellow/red leaves. I know nothing about this plant other than I'd like to grow some one day. LOL! I would probably put something around the seed head and let the seeds dry normally and catch them as they fall. Something like nylon stocking tied loosely around it might work.

Maybe a dumb question, but did your croton bloom first?

The reason I ask this is because it looks like a bloom stalk. I'm not sure how Croton blooms are pollinated, as each one is rather small and looks like a little 'pom-pom'. I've had one bloom indoors once, just this summer, for the first time, but it never did develop seeds. (I couldn't believe it bloomed!)

Blooms on a Croton indoors (other than in a greenhouse) are rather 'rare', so, wow, you 'done good'!!

The difference in the leaf coloration is most likely caused by the change in light. Brighter light results in more colorful leaves. Which direction was the window facing where you had the plant previously?

I agree ~ the difference in the leaf coloring looks quite *cool*!!

Hey, I didn't even know they HAD flowers! I got one at a close-out sale last fall and had no info on it. It's one of my faves now, though - truly beautiful foliage!

Nice job!