How much nitrogen is needed to grow the seeds?
Four ‘O’ Clock Flowers
Certified GKH Gardening Expert
I would not apply any nitrogen until it has some sort of root system to take it up. Having too much may cause them to abort out before they germinate. You can fertilize, but don't do it often. These are not heavy feeders. Just give a very weak all-purpose feed every few weeks. This article will give you more information about them: https://www.gardeningknowhow.com/ornamental/flowers/four-oclocks/four-oclock-plants.htm