Garden SpotGarden Spot

Garden Spot: How to clone a plant

CorrespondentFebruary 22, 2013 

  • Do you want to try?

    The next propagation workshops are 9 a.m.-3 p.m. May 18 and June 1. Classes are limited to 15 participants and advance registration is required. The workshops are held at Ruby C. McSwain Education Center, JC Raulston Arboretum at N.C. State University, 4415 Beryl Road, Raleigh. To register, call Chris Glenn at 919-513-7005. The cost is $100 (for arboretum members only, but nonmembers can join for $50.)

  • 5 propagation tips

    1 For detailed instructions on propagating plants by stem cutting, visit ces.ncsu.edu/hil/hil-8702.html.

    2 Willows have great rooting capability. Soak willow stems in water about eight hours and use that leftover water with your rooting hormone or to water your plants.

    3 Use bypass or scissor-type pruners that won’t mash your stem. Don’t use flat-edge, hammer and anvil-type pruners.

    4 You can use Listerine to clean your pruners if you have used them to work on diseased plants.

    5 Plastic storage containers make great mini-greenhouses. Put your trays with plants on the lid and cover with the inverted container.

“This is why I’m here,” Melanie Kelley of Raleigh said as we walked toward a ‘Green’s Blues’ camellia plant at JC Raulston Arboretum on a cold Saturday morning. She bent down, pushed back some branches as she examined the plant and then carefully snipped several stems.

“I love it because of the color of the flower (dark bluish purple) and the low, spreading growth habit, ” Kelley said.

Kelley was one of several gardeners attending a hands-on propagation workshop at the arboretum in Raleigh. Participants learned how to propagate plants with hardwood cuttings taken at the arboretum, and they took some of the newly propagated plants home with them.

If someone has a plant that you just love and you want one just like it, asexual propagation might be the way to get it. Plants are propagated in two ways – sexual (from seed) or asexual (cloning by tissue culture, including cuttings and grafting). When propagated by seed, the resulting plant might differ from the parent in color or some other way. But asexual propagation produces a clone of the original plant.

You cut a stem from the plant, stick the plant in rooting hormone and then put the stem in a rooting medium. Once the stem has a good set of roots, it can be transplanted.

Every cell has the potential to create other cells, said workshop leader Mark Weathington, assistant director and curator of collections at Raulston. Before sending participants out with their pruners, Weathington discussed how to increase their chances of success with the cuttings.

“Winter is a good time to propagate some hard-to-root plants because the tops are dormant, but we can stimulate the roots to grow with hormones and bottom heat,” Weathington said.

When choosing a plant for cuttings, make sure it’s large enough with lots of branches. Rule No. 1: Don’t disfigure the plant.

Gardeners are more likely to have success with shrubby deciduous plants, such as spiraea, and broadleaf evergreens, such as holly. Hydrangeas and willows also root easily.

Make a cut at an angle, above a leaf, Weathington said. Avoid branches with lots of fruit and flowers because a lot of the plant’s energy has already gone into fruit production. If the plant you want has lots of flower buds, try pinching them off.

Also, Weathington said, if the plant has large leaves, cut off the top of the leaf so it won’t use as much water. You want the plant’s energy to be spent on root production.

Take multiple cuttings from a plant to increase your chance of success. If the plant can spare only one or two stems, don’t take the cutting, he said.

Rooting hormone kick-starts root growth. You can buy hormone solution, such as Dip ’n Grow, in powder or liquid form. Dip the stem in the solution for three to five seconds. If you stick it too long, the solution can kill the plant’s cells.

Stick the stem in a soilless growing media in a tray. You’ll stick the stem deep enough so that it will stand upright, but not so deep that it’s standing in water. You’ll need trays with plastic lids. Once you put the plants in the tray, water it and let it drain for 20 to 30 minutes, then cover with the plastic lid. Don’t let the plant touch the lid.

At home, put your cuttings in a cool spot with relatively bright, indirect light, and provide bottom heat. Kelley’s cuttings are in her garage on a shelf underneath a window. The bottom heat comes from an electric heating pad. A screened-in porch is a fine place to put your cuttings, too, but you’ll want to take them inside when it’s really cold out. If you grow them indoors, Weathington said, the tops will be stimulated to grow, which can sometimes impede root development

All plants are different. Some, like hydrangeas or aucuba, root quickly with roots starting to form in a week or so. Some conifers, on the other hand, can take more than a year to root. Once the plants have a good set of roots and have started growing, they can be planted out.

Kelley said she put her first cuttings into the ground too soon.

“Once the cuttings have started to get secondary growth, I repot them in 2- and 3-inch pots,” she said. “I repeatedly do this every few months for the first year, each time putting the cuttings in slightly larger pots. I move them out to my yard, still in the pots, for a year or so, so that the plants get water and fertilizer just like the rest of my garden.”

The whole process takes time and patience.

Boyette: debragardens@gmail.com

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