70 days. The Scarlet Nantes carrot seeds produce blunt cylindrical seven inch roots, great for bunching. This garden crop thrives with full sun in zones three to nine, and does best in sandy, well-drained soil. The Scarlet Nantes carrot is sweet and tender. The roots can be harvested in around seventy days. This vegetable usually takes about 95 days until it is ready to harvest. Recommended by Utah State University, Scarlet Nantes carrots are sweet, plump, and coreless.