Finally a pinkish bloom opened on this plant, so now it has yellow and pink flowers. Yay!
They're not easy to grow from seed. Only 2 out of 25 seeds sprouted. I used seed starting potting soil (Miracle Gro), and I pre-wet it thoroughly before planting the seeds. I just scattered the seeds on top of the moist soil and put it out in full morning sun. It was also quite hot-- summertime in Phoenix, Arizona. And I watered from the bottom to not disturb the seeds.
Next time I will get more seeds. They only had 25 per seed packet.