Butturfly Bush (Buddleja) is in high demand and popular with gardeners because it’s easy to grow and it’s a magnet for hummingbirds and butterflies, said Josh Zielinski, manager and co-owner at Alpha Nursery (Salem, Oregon).

“Buddleja is kind of like a summer blooming lilac,” Zielinski said.

“It smells like honey on a warm summer day,” said Ryan Contreras, Ph.D., professor in the Department of Horticulture at Oregon State University. He said Buddleja doesn’t require much irrigation and the flowers last a long time.

“I had one flowering with snow on it this past year,” Contreras said.

Before David West became the assistant manager at Krueger’s Nursery and Tree Farm in Cornelius, he worked for 30 years as a landscaper.

“In the beginning stages, we planted a lot of Buddleja and found it would self seed rapidly and spread all over the place,” West said of the landscaping industry at the start of his career. “Left unchecked it would become invasive.”

Soon, Buddleja davidii spread out of cultivation.

“The species produces many thousands of seeds per plant and spreads around, especially in riparian areas,” Contreras said.

Invasive declaration

That invasive tendency led the Oregon Department of Agriculture to declare Buddleja davidii to be a B listed Noxious Weed in 2004, with an updated declaration in 2016.

Zielinski said it was challenging when it was determined to be invasive.

“It’s not the only one but it was a popular garden center plant so that one stung a bit more than other ones,” Zielinski said.

Response

Plant breeders, branding companies, and nurseries responded by developing sterile varieties. Some do and some do not produce seeds, Contreras said. “Some produce very few seeds, but the seeds may be viable.”

The ODA sought input from various entities and scientific advisors, including Contreras.

Contreras said he noted some improvements to the guidelines for testing of different cultivars and offered advice to the ODA. 

“Cultivars that we know exhibit low fertility tend to be complex hybrids of multiple species,” Contreras said, but not all hybrids are seedless. Since then, Contreras’ lab has switched gears to focus on breeding sterile varieties.

Valerie Sikkema, who manages government compliance at Van Belle Youngplants in Abbotsford, British Columbia, Canada, said the nursery has been growing Buddleja for many years. When she started in 2006, Van Belle only grew the old invasive varieties, but the nursery has slowly changed over to seedless or interspecific varieties.

“We still grow some that are potentially invasive, but they are shipped to states and provinces where they are less hardy and much less likely to be an invasive species,” Sikkema said. “Any new Buddleja that we would add to our Bloomin’ Easy line will be interspecific hybrids.”

Sikkema said plant breeders develop non-invasive cultivars of aggressive genera like Buddleja by producing triploids or interspecific crosses.

Kevin Bailey, manager of the Nursery & Christmas Tree Programs at the Oregon Department of Agriculture, works with out-of-state vendors to control the shipment and importation of non-approved Buddleja into Oregon.

“If we receive notice that a shipment has been sent, the nursery inspectors will contact the receiver and issue a rejection for the shipment,” Bailey said. “In the office, we will contact the vendor to make them aware of the quarantine against the non-approved varieties and highlighting the approved or sterile varieties.”

Troy Abercrombie is the program manager for Noxious Weed Control and Native Plant Conservation at Oregon Department of Agriculture’s Plant Protection and Conservation Program. He enforces quarantine of invasive Buddleja and helps educate the public about it.

Abercrombie said sterile varieties of a species like Buddleja that don’t also reproduce vegetatively would greatly reduce the risk of invasion and displacement of native species.

Approving cultivars

ODA’s Nursery Program also facilitates a Buddleja committee of industry and academic partners. The committee members work together to come up with the best ways to determine a cultivar’s sterility and to make changes to the current list of 14 approved cultivars.

Bailey said the program doesn’t advocate during these meetings but provides an opportunity for the industry to work with researchers to refine and define what qualifies as a sterile Buddleja. With this information, they can approach the Oregon State Weed Board with proposed additions and subtractions to the approved cultivar list.

Bailey said he is not aware of any truly seedless cultivars of Buddleja.

“While the administrative rule indicates the approval of seedless cultivars, it is the 2% sterility that is the threshold,” Bailey said. “It is important to keep in mind that the ‘seedless’ cultivars do produce seed and even at 2% sterility, they can produce a significant number of viable seeds.”

He added there are hybrid varieties being produced that are not regulated and are actually quite fertile.

Bailey said researchers continue to develop sterile cultivars with the sterility rate of 2% or less.

Importance

West said it’s important to offer sterile varieties because there’s such a high demand for the long-lasting, impressive showstopper blooms that Buddleja produces.

“But because it blooms so well, it also produces seeds so well and people don’t want to give up the huge blooms of purples and pinks in their landscape creation. And the things you want to attract to the garden really love this bush,” West said. “The right thing to do is try and use varieties that will not be invasive.”

Sikkema said although Buddleja is non-native, it is still a beautiful plant in the landscape and can provide joy for homeowners with their beautiful flowers and lovely scents. As the name Butterfly Bush suggests, they also are able to provide food and habitat for pollinators, including bees and butterflies. 

“Many of the sterile cultivars are great pollinator attractions and they’re really easy to produce quickly, so growers like to grow them and they’re really popular among gardeners,” Contreras said.

Popular varieties

Now there’s a smaller selection that nurseries are available to offer and they are more expensive than other options.

“That’s kind of counter to what it used to be for Buddleja,” Zielinski said. “It used to be a more affordable colorful item than a special patented selection that someone has to pay more for.”

“We dabbled with a few varieties early on and we found them to be lackluster,” Zielinski said. “The foliage wasn’t good and the overwintering wasn’t great. For some of them, the flowers weren’t exciting or just blah.”

However, Zielinski found the Proven Winners® series to be much better. These include Buddleja  ‘Miss Violet,’ Buddleja ‘Miss Ruby’ and Buddleja  ‘Miss Molly’.“They grow well and overwinter better than a lot of other varieties,” Zielinski said.

Van Belle also grows those same three Proven Winners varieties. In addition, they sell two Bloomin’ Easy varieties that are interspecific hybrids so they are not regulated and are allowed. These are Buddleja Blueberry Pie™ (Buddleja  ‘PODARASNGA 9-15’ PPAF, CPBRAF) and Buddleja Birthday Cake™ (Buddleja  ‘PODARASNGA 3-3’ PPAF, CPBRAF).

Krueger’s also grows and sells ‘Miss Molly’, which is known to be low and compact, and is growing a Proven Winners dwarf variety called Lo & Behold® ‘Blue Chip Jr.’ (Buddleja ‘Blue Chip Jr.’ PP26581, CP5620).

Contreras said Lo & Behold® ‘Pink Micro Chip’ (Buddleja ‘Pink Micro Chip’) is also popular.

Future considerations

West said Krueger’s Tree Farm is still considering sterile Buddleja varieties to be in the trial stage to see how they perform long term.

“We’re seeing what customers say about how they behave and what they do,” West said. “It depends on the variety, but for us at Krueger’s we’re still experimenting with what we have.”

West said the Buddleja needs to grow for a few more years to make sure it doesn’t eventually revert back to becoming fertile. So far, the customers have said ‘Miss Molly’ has worked well.

Zielinski said he’d be interested in having a dialogue about the possibility to grow fertile varieties to export before blooming to retailers in places where they aren’t declared invasive. He wants to be able to grow Proven Winners’ Pugster® Blue Butterfly Bush (Buddleja  ‘SMNBDBT’ PP 28794, CP6486) because his customers continually ask for it, but he’s not able to carry it.

“I’m grateful that we have the ability to grow something at all,” Zielinski said. “I don’t know what it would do for my bottom line if we didn’t.”

From the July 2025 issue of Digger magazine | Download PDF of article