Rudbeckia can reach over three feet in height, so be cautious when growing plants indoors. Leaves can extend beyond six inches, with flowers two to three inches in diameter. Once they start blooming, plants will spread between 12 and 18 inches, so keep this in mind if you're growing multiples. Certain varieties spread further than others.

Proper spacing significantly impacts results; it boosts air circulation, keeps leaves dry, and helps prevent disease from spreading.

While rudbeckia is a drought-tolerant plant, always prevent the soil from becoming bone dry. Your plants need sufficient water to produce healthy roots, so aim for about one inch weekly. This provides just enough to soak into the roots; you'll know to water when the top of the soil feels dry.

If conditions are sandy or you're experiencing excessive heat, boost watering by an inch or so until the top layer of soil stays sufficiently moist.

Rudbeckia is susceptible to several predators, including aphids, caterpillars, Japanese beetles, and two-spotted spider mites. Each of these can chew away at roots, stems, leaves, and blossoms, destroying your entire crop.

Insecticidal soaps, sprays, and horticultural oil are effective at removing most pests. Mammals such as raccoons and skunks eat larvae left behind by pesky intruders, while predatory mites feed on spider mites. Additionally, look for products containing Bt and Bacillus papillae to help keep pest populations down.

Rudbeckia can fall prey to several common diseases, including bacterial leaf spots, fungal leaf spots, downy mildew, and fungal rot. If you notice discoloration, holes, or spores on your plants, take action immediately.

The presence of these devastating pathogens is boosted by excess leaf moisture, so proper spacing and removing dead plant material can work wonders. Eliminate as much moisture and humidity around plants as possible.

Irrigation is another cause of excess wetness, so use drip irrigation to reduce risk. Apply fungicide early and often to combat fungal diseases, and get rid of any affected plants promptly.

Your rudbeckia plants require several nutrients to reach peak growth. Use bone meal to increase the calcium content in your soil; this necessary ingredient offers structural support to cells and boosts strength when plants are stressed.

Conduct a soil test to determine phosphorus levels. Many gardens will require a phosphorus-rich fertilizer, but if you reside in an area with naturally high phosphorus content, it's not needed. A slow-release fertilizer can be spread at a rate of one pound for every 100 feet once new leaves start growing. Add a 1/2 pound midway through the growing season.

Rudbeckia comes in an assortment of colors and sizes.

• "Becky Mixed" incorporates hues ranging from lemon yellow to reddish-brown.
• Rudbeckia grandiflora grows to an impressive 39-47 inches with showy yellow centers, spreading up to 29 inches across.
• "City Garden" grows to just 10-12 inches in height and only spreads to 18 inches, making it a go-to for indoor containers.
• For bronze orange and red shades, go for "Autumn Colors," which features dark blooms ranging from 20-23 inches in height and spreading up to 18 inches.
• "Cherokee Sunset" grows up to 29 inches tall and spreads up to 16 inches, with a colorful mix of yellow, red, and brown blossoms.