Professor shares best technics for propagating trees and shrubs

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If you have ever spent an afternoon carefully preparing cuttings to clone that favorite shrub, only to watch in despair as every one of them turned black and died, heed this advice from a master of the subject.

Matthew Chappell, University of Georgia professor and extension service horticulturist, got up in the wee hours of the morning to drive to Augusta and talk about “Propagating Difficult Plants” at the monthly meeting of the ARC Growers Meeting.

The next chance to take advantage of Chappell’s tips will be January through March when you can take hardwood cuttings. (The soft-wood cuttings are from new growth taken in the spring, and the semi-soft-wood cuttings are from bendable stems that are taken before the end of July for best results.)

Which type of cutting to use depends on the plant, Chappell said. Maple trees, for example, do best with hardwood cuttings.

The absolute best source of information about plant cuttings, Chappell said, can be found in the Hartmann and Kester textbook on propagation and similar references by Michael Dirr, who literally wrote the encyclopedia on trees and shrubs.

You also can learn from past mistakes and successes by keeping records about your propagation work.

When you’re ready, drag yourself out of bed early. The best time to take cuttings is when a plant is hydrated the most, and that’s around 6 a.m. You will want to immediately place cuttings in water.

Chappell showed the difference between new plants from cuttings of various lengths. Bottom line is that the longer the cutting is the better your result will be. You want a terminal bud for best results but a stem with multiple nodes does well, too. Chappell talked about one nursery where they take 12 inches with great success.

Plan to recut the end and also wound the end by cutting into the stem until you see a change in color. Chappell recommended wounding both sides to get equal distribution of roots.

Using root hormone isn’t often necessary, but if you want to use it, Chappell said the liquid variety is best because it coats better than powder root hormone. If you do use the liquid hormone, do not leave a cutting in liquid for more than 5 seconds, Chappell said. It contains alcohol and will dry it out.

The medium to use must be porous. Oasis block, also known as floral foam, is a good medium. Using containers instead of trays will give you a better chance at success because they can maintain the steady temperature and moisture levels that are crucial to keep disease away, Chappell said.

While soft- and semi-soft wood cuttings must be misted, hardwood cuttings should not. Hardwood cuttings should be placed on a heated pad when they begin to bud out.

While it’s tempting to fertilize, do not. The same goes for repotting. Chappell said the cuttings should over-winter in the same pot for best results.

Be a vigilant guard to keep disease out. It’s important to take cuttings only from healthy plants, Chappell said. And if any of the cuttings start showing signs of disease, remove them immediately to save the others.


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