42-54 days. Grow this amaranth for its nutritious, flavorful foliage with a hearty spinach flavor that is sweet and slightly tangy. Amaranth loves the heat and makes a great salad ingredient when spring greens crops have been harvested or are bolting. Steam, stir-fry, sauté or mix with spaghetti sauce, rice or meatloaf. Unlike wheat, the seed is also easy to harvest,is 20% protein, and ranks 75 out of 100 as a complete protein: higher than milk, soybeans, or whole wheat.