Rudbeckia is a rhizomatous herbaceous perennial plant, native to North America; develops large erect tufts, made up of thin, semi-woody stems, which bear numerous light green, lanceolate leaves, up to 10-15 cm long, which tend to diminish in size moving towards the apex of the stem.
The stems of the rudbeckia they are branched, and at the apex of each small branch large daisy-shaped flowers bloom, with a diameter close to 10 cm, of yellow-orange color, with a brown center, very showy. The plants continue to bloom from summer until the first cold of autumn, developing up to a height of about 100-110 cm. Generally during the winter the rudbeckie dries up, to start to develop again the following spring. To encourage more abundant flowering, remove the withered flowers.
Among the varieties of rudbeckia more widespread and appreciated for garden cultivation we have Rudbeckia hirta and Rudbeckia bilobata, although nowadays the cultivars available in greenhouses and nurseries are very variegated and complex.
Rudbeckia plants are planted in a sunny, or slightly shady, place. They are plants that love direct light and do not fear the cold, and can also be grown in areas with very cold winters. They do not even fear the summer heat and tolerate environmental pollution well and are therefore an ideal species for those who are looking for rustic plants that can adapt and resist well even in prohibitive conditions.
From March to October we try to water the rudbeckia only if the soil dries completely for a few days. In fact, this plant does not need large amounts of water to grow well, on the contrary, particular care must be taken not to overdo the humidity of the soil. During the vegetative period, provide fertilizer for flowering plants, every 10-15 days, mixed with the water used for watering.
The rudbeckie are very vigorous plants, which develop without problems even in the common garden soil, but prefer quite rich and very well drained soils. If desired, it is possible to grow rudbeckia in pots for convenience or necessity, but we will absolutely have to find top quality soil to have satisfying results, remembering to fertilize the rudbeckia from time to time, especially in spring at the beginning of development.
Of fundamental importance is the use of a draining soil and therefore enriched with a good quantity of pumice or medioperlite stone, inert substances that improve the soil structure and facilitate water percolation. This prevents water stagnation that can cause dangerous root rots.
The multiplication of these plants occurs by seed, even directly at home, in autumn or early spring; plants tend to self-seed every year. In autumn it is also possible to divide the rhizomes and vegetatively multiply the plant.
Rudbeckia: Pests and diseases
The rudbeckie are generally not affected by pests or diseases but care must be taken to watering because an excess of humidity in the soil could cause dangerous root rot.