Right now it is fall, and I'm looking for a flower seed that grows quickly at this time. I'm also hoping that they are convenient to purchase at like Home Depot or some sort.
Do amaryllis flowers or sunflowers grow fast and well here?
Thanks

depending of your planting number area.. I live in Central Florida - Planting region number 9 before was in region 10B

Amaryllis bulbs are very easy to grow and will multiply easily if they are planted in a shady area and well drained soil.
I'm not sure about the Sunflowers but it should be no problem if you plant in the fall by spring they should be in full bloom.
Personally, I prefer the Hibiscus which blooms every day in full sun and grow real fast in my area.