How to Take Care of Black-Eyed Susans

Plant seed or transplants after all danger of frost is over and temperatures reach 60 degrees Fahrenheit during the day. Plant them in full sun and well-draining soil. Scatter the seed, press them lightly into the soil, cover them with a light layer of soil, water and keep the area moist. For transplants, dig a hole as deep and two times as wide as its pot. Place the plant in the hole so it sits at the same depth it was in the pot and fill the hole with soil. Space the plants 2 to 3 feet between plants to ensure good air circulation.

Apply a thin compost layer and cover it with 2 inches of mulch. The compost is all the fertilizer the plants need and mulch keeps weeds from growing. It also keeps the roots cool and moist. Repeat the compost and mulch every spring with perennial flowers.

Remove faded flowers by pinching at the base of the stem behind the flower. This encourages more blooms.

Give plants supplemental water if there is less than 1 inch of rain per week.

Cut stems 1 to 2 inches above the soil line once a killing frost occurs.

Divide the clumps every 3 to 4 years in the spring by digging up a clump with a shovel and dividing it into two or three sections.

Watch for powdery mildew on the leaves, which shows as a white powder. Black-eyed Susans are susceptible to the disease and the leaves turn yellow and fall off. Good air circulation between plants prevents the problem, which is why proper spacing and division is important. Prune infected stems and destroy them. Stay away from nitrogen-rich fertilizers, as they cause the problem by producing crowded plants. Treat the plants with a fungicide.