All the crosses of hibiscus rosa-sinis are unique and even siblings from the same pod will not have identical flowers as the Hibiscus rosa-sinensis was crossed through hundreds of years by men and nature though showing a never ending gene pool.
The seeds should be sown between end of February and latest July. As from July the days are getting shorter the seedlings wouldn’t grow strong enough to make it well through the long dark winter months in our colder climate. During the winter season the seeds would take rather long to germinate and would grow scraggly, so better to grow them during the normal sowing season unless you grow them with extra light.
Take seed raising mixture, maybe extra mixed with Perlite, moisten it, place the seed on top and cover slightly with the soil. Cover the pot either with clingfilm or place it in a small “greenhouse” covered by a plastic dome, put it on a warming mat or a warm place. After about ten days (up to 5 months) the first leaves will appear and as soon as the first true leaves are growing remove the cover from time to time to harden up the seedlings. Please water very carefully as those tiny seedlings are very sensitive to wet soil. As soon as the second pair of true leaves appear the fertilizing should start.
Normally after 12 to 18 month the first flower will show and this is the most exciting and rewarding moment ! I know what I’m talking about as I’m hybridizing since over twenty years myself and still every new bloom is very exciting.
when you do your own crossing with your hibiscus you’re the hybridizer. Please keep in mind that if you purchase seeds from a hybridizer he will always stay the hybridizer of those special crosses. You may name the resulting new variety, but you will only be the grower, not the hybridizer.
I have normally from February till July freshly harvested seeds from Hibiscus rosa-sinensis available so you are welcome to ask for a list of the crosses.