Purpletop tridens is a perennial grass that can grow anywhere from 2 1/2 feet to 7 feet tall. Average height is usually around 3 to 4 feet. The blooming period for purpletop tridens is midsummer to early fall and usually lasts about two to three weeks. After the grass blooms, the purple color fades to brown. Purpletop tridens prefer slightly dry conditions and partial shade and soil that is clay-like or with sand and rocks. According to the U.S. Department of Agriculture, purpletop tridens have adapted best to the eastern United States.
Plant your purpletop tridens in early spring when the ground is still moist and temperatures are still cool. Pack the soil with a roller to ensure that the seeds develop. Purpletop seedlings do not do well with a loose soil. Sow 10 to 15 lbs. of seed per acre if you are using a seed drill. If a broadcast method is preferred, increase the seed count to 20 to 25 lbs. of seed per acre. Seeds should be planted at a depth of around 1/4 inch. Purpletop seeds do not grow very quickly, so you will not see growth for at least a week or longer.
Apply 20 to 40 lbs. of nitrogen fertilizer per acre after the first summer of growth. Use 40 to 80 lbs. per acre after the second summer that the grass has grown. Manure compost works well on purpletop tridens. Fertilizer that is applied in later years will ensure growth and keep the grass healthy.
Use rotational grazing methods to keep the grains growing strong. Allow livestock to graze the purpletop tridens down to levels of 3 to 6 inches. The tops of the purpletop provide nutritional grain for livestock, and the grazing controls weeds and keep the plants from becoming too packed.
Avoid watering your purpletop tridens. Water is usually not necessary. Purpletop tridens grow better with little water, and too much moisture can thin out your grass due to rot. The root system is thick and fibrous and holds in all the water that the plant needs for survival.