Bees Do It. And So Can You.

Just as the right patterned fabric or a few throw pillows can make a whole room work, so functions coleus in the garden.

It’s hard — impossible? — to think of another plant whose varieties display such a diverse concentration and location of color in their leaves. Coleus’s seemingly infinite genetic expressions can inspire a gardener planting a container or an entire bed, lending color nonstop through a stretch of frost-free months.

If the experience of Chris Baker, a longtime nurseryman and passionate coleus breeder, can be submitted into evidence, these plants help make for a rather color-filled life, too.

Mr. Baker recalls the windowsill above his grandmother’s kitchen sink a long time ago, where a little glass jar of water held the latest round of coleus cuttings that Grandma Gert was rooting. Their “crazy colors,” which he has likened to the botanical equivalent of a Hawaiian shirt, left an indelible impression. The image was still with him decades later when he came to the practice of propagating coleus himself — not on a windowsill, but in a greenhouse.

His was an indirect route to nurseryman and then, in time, to coleus breeder, said Mr. Baker, who after earning a degree in music from Ohio State University set his modest career goal as “rock star.”

“It didn’t quite work out right,” he said. “So I drove a cab to make ends meet, and when I got held up with a pistol in my ear one night I said, ‘I think I should do something else.’”

A job in a greenhouse was the first step before he and his wife, Nancy, opened their own garden center in 1982 in Alexandria, Ohio, near Columbus. Today their son, Nick, and daughter-in-law, Pam, have taken on the family business, Baker’s Acres Greenhouse, but one greenhouse at the nursery remains Chris Baker’s domain. It’s the one stuffed with a riot of his beloved genus, including many of his own varieties — among them Cosmic Nick, Pam’s Glam, and ones named for every other family member, too.

The Education of a Hybridizer

Mr. Baker got his start in breeding with a gift of hand-me-down plants from two friends, Ken Frieling, a coleus breeder who died last May, and Mr. Frieling’s partner, Tom Winn, who died in 2013. They operated Glasshouse Works, a beloved rare-plant nursery in Stewart, Ohio. One September about 25 years ago, Mr. Frieling told Mr. Baker that he had some large stock plants — ones he’d been taking cuttings from to propagate his nursery inventory — that he wouldn’t be using anymore. Did Mr. Baker want to come rescue them before frost hit?

At Baker’s Acres, he stashed them in a retail greenhouse that was closed to the public for the offseason. The adopted plants, which had flowers on them, went to seed, self-sowing into the greenhouse floor with abandon.

“All the seeds dropped in the cracks of the pavers,” Mr. Baker recalled, “and these little seedlings came up. And I said, ‘Oh, look at that.’ And that’s how I got started. I picked out some really good ones and named them.”

The seedlings got him thinking: “Wow, what if you cross this and cross this?” So he did, using a magnifying glass as he moved pollen from plant to plant with a tiny paintbrush in his first deliberate efforts at hybridizing.

The process wasn’t always straightforward — crossing a reddish-leaved variety with a yellow one didn’t guarantee orange, for example, and “a good pink that will stand up in the sun is hard to get,” he said. And it could be tedious.

So he set some plants outside that he wanted to cross, “and the bees did it for me, and I got the same results and I said, ‘This is crazy.’ I threw away the magnifier and let the bees do it, and here we are.”

Up come a fresh generation of possibilities each time, and it’s breeder’s choice — the process of selection, the basis of plant breeding — to decide which subset advances to the next round. The math is wild: In the past 10 years, Mr. Baker said, he has sown 10,000 to 20,000 seeds annually, “and I probably get 10 to 20 good ones each time.”

Once he identifies a plant worth naming, he multiplies it by cloning — taking cuttings — not by seed any longer.

Breeding for More Than Just Color

Mr. Baker could have supplied his customers with a flashy assortment of coleus ordered from wholesale sources, skipping years of effort (but missing all the astonishment). The International Coleus Society has records of more than 1,800 named cultivars of Coleus scutellarioides, a mint family relative that is perennial in its native range in parts of Southeast Asia down into areas of Australia.

Estimates of how many are commercially available range from about 400 to 500 varieties. Two specialty mail-order sources with deep lists that he recommends are Rosy Dawn Gardens in New Hudson, Mich., with more than 200 varieties, and Taylor Greenhouses in Portland, N.Y., with about 140.

The extensive breeding program established in 2003 at the University of Florida has also greatly influenced the coleus marketplace; its varieties have been named and commercialized by familiar horticultural wholesale brands including Ball FloraPlant and Proven Winners.

But the work of smaller, independent breeders like Mr. Baker is important creatively in the market, and to the evolving looks of coleus. His greenhouse houses maybe 50 of his own varieties among 125 stock plants used in ongoing breeding and to propagate inventory for retail customers.

Modern breeders have focused not just on leaf color, but on traits including leaf size and shape.

Other important breeding directions have resulted in coleus, once regarded as a shade annual, that is adapted to sunnier areas of the garden, creating plants whose urge to flower is delayed, since for gardeners it’s all about those leaves. Another goal: plants inclined to branch more and stay bushy.

“To get the older varieties to branch, you had to pinch the top out,” said Mr. Baker. “Somehow I seem to have latched onto that gene, because the newer seedlings I’m getting now branch like crazy.”

He named those keepers his Branch Manager Series, but it isn’t always traditional good looks that christens a variety. “Every now and then I’ll get a seedling that is so ugly that it deserves a name,” he said, like “a black coleus with leaves so strange that they look like they were grown beside a faulty nuclear reactor.”

Say hello to his Evening in Chernobyl.

If you find a coleus you love and want to be sure you have it again next year, bring the plant in before fall’s first frost and put it near a window, said Mr. Baker, then make like Grandma Gert.

“Around mid-March, just take a little cutting, like a three-inch cutting, and put it in water,” he said, “and as soon as it gets about an inch of roots on it, put it in some dirt and you’ll have a plant ready to go by the middle of May. It’s that easy.”

Margaret Roach is the creator of the website and podcast A Way to Garden, and a book of the same name.

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