The ubiquitous ohia lehua grows from near sea level to Hawaii’s summits. Despite its versatility, the plant is notoriously difficult to propagate.
“Everybody said it was tough, so I didn’t do it,” said Jerry Hess of Pahala, one of roughly two dozen participants at a 30-minute workshop held Saturday at Amy B.H. Greenwell Ethnobotanical Garden in Captain Cook.
Hess, who owns a small plant nursery, said he’d tried to grow the trees from seeds “smaller than pepper, but never got one to pop.”
Brian Kiyabu, Greenwell Garden’s horticulturist, led the workshop, sharing his secrets to successful cultivation using ohia cuttings.
Wayne and Clarice Suzuki traveled from Hilo for the midday presentation. The couple have started citrus and magnolia plants by air-layering — a process in which bark is removed from a branch, which is then wrapped with a growing medium including a rooting hormone, while still on the tree. After several months, roots develop and the branch can be separated from its parent and grown on its own.
Kiyabu said though air-layering can be effective for starting ohia trees, the process, at best, results in one additional plant. Using the same branch, a grower can get six or seven cuttings, increasing the odds for success.
Kiyabu noted that growing a plant from a cutting is “basically cloning.” Though the ohia is one of the most common trees on Hawaii Island, some are more highly prized. Select a parent with desirable features. Liko, new leaves, range from light green to dark purple. Lehua blossoms can be yellow, orange, red, pink or, rarely, white.
After a parent plant is chosen, Kiyabu told workshop participants, find a “greenish-brown, younger branch,” a maximum one-fourth-inch in diameter.
“Wherever there’s a leaf is called a node,” Kiyabu said. “That’s where roots develop, lots of cell activity.” Make a 30-degree cut at the node and trim off any wilted leaves. Dip the 3- to 6-inch cuttings into a hormone solution for 10 to 30 seconds, then stick them into a growing mix — Kiyabu uses a 2:1 blend of perlite and vermiculite at Greenwell Garden.
Roots may develop “anywhere from six weeks to three to six months,” Kiyabu said. “Tug a little — resistance means growth.”
Depending on the parent plant, Kiyabu said, between 40 and 100 percent of the cuttings he begins with eventually develop into thriving plants. Almost every ohia growing at Greenwell Garden, he added, began as a cutting.
Participants provided their own cuttings, or shared with others, for some hands-on practice.
“Seems easy enough,” said Wayne Suzuki. His biggest concern was finding a way to satisfy the cuttings’ need for constant humidity. Greenwell Garden’s irrigation system mists them for 10 seconds every 10 minutes.
Clarice Suzuki devised a simple solution: Place the pot inside a clear plastic bag tied at the top.
Kiyabu said the idea would work, as long as the plant didn’t touch the plastic and was watered as needed. Another option, he said, would be using an empty Costco-sized cranberry juice bottle to cover the potted cutting.
“When you first start, you’re going to be unsuccessful,” Kiyabu said. “Don’t worry about it, just keep going.”