You might as well plant em and see what you get. You'll get more for the white than black, and also campions and poppies will go for more than cactus. When I have to grow plants I use characters on my old bod gathering account that don't do anything else. I park them near a chest that has greater cure and greater poison kegs, stick a water trough nearby, and put 4 or 5 empty pouches in each persons backpack. Then I put 8 dirt filled plant bowls in each of those pouches (four on top, four on bottom evenly spaced), water each bowl twice and plant the seeds. It will take about 8-9 days of logging in once a day after server up to water and potion them before you can set them all to deco mode.
You can probably get 25-50k per white plant, depending on your shard. On Baja black plants sell very poorly, maybe 1-5k per, but different shards have different levels of interest in those.
If this amount of money isn't tempting to you, or you don't feel like messing with it, you can probably sell the white seeds for 10-20k each, not sure about the black seeds.