Unpacking American Gold Rush

Lowell Halvorson

A top-seller for Intrinsic Perennial Gardens in the Chicagoland area was Goldsturm until Septoria troubles spoiled the sales. The black spot fungus drapes it in a ratty, tattered appearance that strips away any market value. Continued production required fungicides, something Brent Horvath, the owner of the finishing nursery and a breeder, was reluctant to use.

The famous photo: The trial garden at the Chicago Botanic Garden.

Returning Rudbeckia fulgidas to their former glory is important because Goldsturm is normally a landscaper’s best friend in August. Rudbeckias bloom generously in high summer heat when other perennials look worn and tired. They require absolutely no maintenance beyond natural rain and mulch. Come back two decades from now and Goldsturm will still be blooming. For landscape perennial plantings, this is sweet. Once and done, really. Sales to home gardeners are good, but the commercial market drives the revenues in this category.

Filling the revenue holes dug by Septoria became Brent’s puzzle. In 2011, he planted a field of rudbeckias with traits he admired and let the bees go to work. The next year, he selected the most promising seedlings from the seeds he’d saved previously. Again, he collected seed and grew the plants out the following year. Re-selecting a new batch of 10 to 20, he began propagation testing over the next two years, selecting a few winners that he would then propagate into the thousands. By this time it was 2016 and Brent named his winner.

American Gold Rush has two signature features. First is aggressive disease resistance to Septoria due to a skinny, hairy leaf with a silvery sheen. The fuzz helps limit the number of spores that contact the leaf’s surface. It also keeps the plant less wet by pushing away vapor and helping shed water, maintaining an air cushion under and over the leaf as long as possible.

“That fungus easily survives and thrives on the leaves that don’t have hairs, especially with overhead irrigation, which is a typical nursery practice,” said Brent. However, a local rudbeckia native to Ohio, R. fulgida var. deamii, didn’t have these problems. Intrinsic grew it, they liked it and it didn’t have the disease pressure. R. deamii went into the breeding plot, along with five or six other species, where its bloodline became an important influence.

American Gold Rush also happens to be a visual break from Goldsturm. On a sunny day, the leaves look decidedly silver; on a cloudy day, they look more gray. The flower petals droop a little and the color tends to shift slightly to the yellow. Goldsturm, by contrast, has a table-top style of flower, flat across the top, with petals a little more golden. Underneath, you’ll find the wide, shiny leaves.

Another very visual signature feature is obvious in the famous photo with the domes (pictured on this page). That garden you see is in the second of a three-year All-America Selections trial held at the Chicago Botanical Garden. Two-inch plugs were supplied by Raker-Roberta’s in 2016 and the staff dropped them on 3-ft. centers in a diamond pattern. You’re looking at a total of 15 plants in the photo. Richard Hawke, the director of the trial, snapped that picture on August 17,  2017, with his iPhone 6S on a cloudy day.

“There’s a gravel path that goes around the main garden in a circle. When you come off the bridge, it comes to the trial gardens and you are dropped at the entrance,” said Richard. “You could see the display from a mile away and it was a draw.”

To get this look, you need proper spacing. Planted closer, rudbeckias merge together to form a loose hedge of color. Spaced apart, all rudbeckias attempt to form a dome of some sort, but American Gold Rush makes the best one. The dome appears the first year and comes to full size by the second year, remaining at the same height thereafter. When the trials closed, the specimens measured 28-in. high and 40-in. wide.

If you happen to be in the décor business, that domeness does appear in containers. Mount Cuba did a 3-gallon decorative pot last year and it was 30-in. wide, almost like a mum.

An analysis of rudbeckias would not be complete without discussing vernalization. Goldsturm was famously stubborn on the issue. It didn’t flower the first year, requiring vernalization in order to show any sort of flower display on the retail bench. For American Gold Rush, vernalization isn’t required, but it really helps. The plant builds up the crown over winter, then focuses on growing out good tops for spring. Without vernalization, it goes straight to the tops without building out a strong crown first.

If you don’t have Septoria in your sales footprint, Goldsturm still works, but if your rudbeckia sales have tanked, switching to American Gold Rush gives you a working solution with an explanation of why. The cultivar also adds that nifty domed garden look, which is easy and affordable for landscapers to reproduce.

American Gold Rush Rudbeckia stats:
• Bred by Brent Horvath, Intrinsic Perennial Gardens
• Introduced in 2016
• AAS Winner in 2020
• PPA Perennial Plant of the Year 2023

Lowell Halvorson is a consultant and writer in Fairfield, Connecticut, for retail and wholesale horticulture, specializing in business development. He also covers the breeding community for GrowerTalks magazine. You can contact him at (203) 257-9345 or halvorson@triadicon.com.