Rudbeckia flowers are easy-to-grow perennials that have golden-yellow petals with black or purple centers. The most common variety is the black-eyed Susan. They are summer-blooming, grow 2 to 6 feet tall and attract butterflies. Rudbeckia plants are somewhat drought-tolerant and disease-resistant. They are hardy in USDA Zones 3 through 8, so they can withstand winter temperatures to about minus 30 degrees F. The best way to plant Rudbeckia flowers is in clumps or borders in vegetable gardens where they will receive full sunlight.
Plant your Rudbeckia flowers in the spring in a garden that gets full sun to light shade and has well-drained soil. Till the planting site and loosen the soil 12 to 15 inches deep. Mix into the soil a layer of organic compost that is 2 to 4 inches thick.
Space the Rudbeckia plants about 2 to 3 feet apart. Dig a hole for each plant that is the same depth as and twice the diameter of the pot.
Remove the Rudbeckia plants carefully from pot and place them in the holes so that the tops of the root balls are at the same level as the ground surface. Backfill the soil and firm gently.
Soak the soil around your newly-planted Rudbeckias with water. Add a 2-inch layer of organic mulch around the plants to control weeds and keep in moisture.
Water the Rudbeckia plants during the summer to supplement rainfall if it rains less than 1 inch per week. Spread thin layer of organic compost around the plants every spring.