Shasta daisy takes awhile to turn to seed. The easiest way I know how to explain it is wait till the entire head turns brown while on the plant. The best indication that the seeds are ready is that the stem underneath the head will also start to turn brown, I usually just take a peek underneath the head and make sure there is no green. Some of my shasta daisy's take several weeks to a month to fully develop.

Once the head and underneath have fully turned brown u will find the seeds in the head, I have added you a picture of the seeds so you know what your looking for.

Yes, you can plant the seeds next spring or you can go ahead and plant them this year if they are still small by the time of frost you can always protect them or you can even winter sow them. Shasta's do not bloom their first year when grown from seed so the sooner you start them the sooner you will get blooms.

Here is a link that might be useful: Shasta Daisy Seeds

Thank you for all the info. Very interesting.

Have a good garden and lots of color :))

Caroline