Orange seeds have this annoying little husk on them. The husk keeps the seeds from soaking up with water and sprouting inside the fruit. If you peel this off, more of your seeds will germinate. They'll sprout faster too. Most of my seeds sprouted within a week (some varieties take longer, don't get discouraged if yours do) without the husk and I gave up waiting on the ones with the husk. I never found out how long it takes, but it IS a lot longer.