By our calculations, you should look at sowing Yellowstone about 14 days before your last frost date.
Ready to harvest in 70-75 days.
This is a stable open-pollinated hybrid variety, not patented.
This carrot is believed to be a child or sport off of the Dutch yellow heirloom carrot, Lobbericher, so the other carrot in its parentage is unclear. 1
Hybrid Yellowstone, Yellowstone Hybrid, Yellowstone F1, Lobbericher Improved, Yellowstone OP, OP Hybrid Yellowstone