Some Cutting Remarks on Short-Lived Plants

While most of the garden is growing furiously thanks to all the rain, a few individuals are dragging their feet, not looking quite up to snuff. They’re showing signs of plant senility. It happens to some of the best.

Perhaps you know the look. Leaves become stunted or spare, stems woody, and they certainly don’t flower like they used to. Some plants are naturally short-lived in the garden.

They’re soon candidates for the compost heap, although cuttings should be made first, so their progeny can continue on. With some plants, this is the only way to make sure they last longer than a few years in the garden.

I’m thinking of plants like marguerites, penstemons, sages, dianthus, and the lime-leaved helichrysum, or shrubby things such as lavender, santolina and heliotrope. I’m sure you can think of a few others.

Geraniums, for instance. An acquaintance stopped me the other day and asked how she could find a certain geranium (a fancy-leaved pelargonium, actually). Hers was getting old and hadn’t flowered in a while but she loved it and wanted to replace it with another.

I told her that the trouble with trying to find another is that many plants appear for a few years at nurseries, then they disappear from the benches. Replacements can’t be found, but you can take cuttings.

Some plants are easy to start from cuttings though others can be maddeningly difficult; all those mentioned above are in the easy-to-moderate range.

I always have a few rooting behind the garage, just in case this is the year some favorite plant decides to call it quits. It’s cheap insurance and if it turns out I don’t need them, I can give them away. One friend’s yard is practically landscaped with cuttings that I didn’t need.

A cutting is simply the top several inches of growth on a stem. Sever it cleanly and remove the bottom leaves so you have a stem that you can insert in a rooting medium. Any large leaves that remain on the upper portion are usually cut in half to reduce transpiration. Don’t take cuttings of stems that are about to blossom as flowering shuts down rooting.

While making roots, my cuttings bunk in an old aquarium behind the garage. The trick with cuttings is to keep the tops from wilting while you keep the bottoms from rotting.

Adding a glass top to the aquarium gives the cuttings lots of light--but no direct sun--and the air inside stays moist and humid, which keeps the tops from wilting.

I put several cuttings in a clean, plastic, 4-inch nursery container. To keep them from rotting, I pot them in pure sand or pure perlite--both are completely mineral. There’s no organic matter at all in the potting medium.

I water them when they become dry, but otherwise keep the rooting stems barely moist so rot can’t develop. It’s more important that the leaves stay moist since there are still no roots.

It takes from two weeks to more than a month for the cuttings to make roots, and once those roots are longer than an inch, I gently move each plant into an individual pot filled with regular potting soil, and then slowly move them into more and more sun.

The stems and leaves contain enough energy to sustain them during the rooting process, but obviously they cannot live for long on a diet of pure sand or perlite.

There are dozens of variations on this theme. Some plants root better if older, “hard” wood is used; others do best when the cutting is taken from newer, softer stems. Some root real fast if the stem ends in a “heel,” that section where one stem is attached to another. A few plants root best when they are dormant.

But most root best when they are actively growing in spring, which is why my aquarium will be chock full of cuttings now through April.

There are also dozens of other ways to vegetatively propagate plants, some even easier than cuttings, and some done at other times of the year.

“Vegetatively” means using a piece of a plant to start another, rather than starting from seed. Vegetative propagation guarantees that the progeny are identical to the parent, whereas seed-grown plants are similar but not identical.

For instance, to start new plants of a unique variegated potato vine that has light green leaves edged and splashed with gold, I simply buried a few of the twining stems in the dirt and they made roots.

I then cut the rooted piece from the plant and had a new, identical plant. If I had grown it from seed, I might have had leaves splashed with gold but probably not. Most likely it would have reverted to plain green.

To get more plants of a spectacular--but slow-growing--double-flowered, pinkish-purple Japanese anemone that I could no longer find at nurseries, I made root cuttings.

I took 2-inch-long slices of roots that were about a quarter of an inch thick and buried them in an upright position just below the soil, in a container filled with potting mix. They sprouted and this spring I have a pot full of baby anemones.

I learned about this fun technique in a new English book on propagation that has been republished here as “The Complete Book of Plant Propagation” (the Taunton Press; $29.95).

While many of the plants described in this book won’t grow well here, the techniques I’ve tried work fine. In fact, I now have so many little plants that I may soon find myself in competition with the corner nursery.