New Plants From Old--the Basics of Cuttings : Horticulture: Many house plants root easily from softwood stem samples. A moist, bright environment is needed for them to thrive.

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Many of today's retirees probably remember their mothers or grandmothers hiding certain plants when certain visitors were expected. The guests were suspected of secretly removing cuttings to the detriment of showcase ornamental plants.

While such raids no longer seem to be a problem, the basic idea--duplicating plants through cuttings--is a good way to obtain desirable plants at little cost. Some house plants, such as many philodendrons, are so easy to grow that they will root even in a small glass of water.

But don't clip someone's pride and joy without their blessing. Fortunately, most prospective donors feel a request vindicates their plant selection and cultivating abilities.

There are two basic ways to propagate plants: by seeds (sexual propagation) and by vegetative means (asexual), which include cuttings.

Plants from seeds may vary from the original, for better or worse. But those propagated vegetatively duplicate the original, which is useful for increasing plants with desirable characteristics. While the technical details of asexual propagation fill many books, just remember that the new chromosomes will be the same as in the cell from which they came.

Which brings us back to stem cuttings as the usual method of vegetative propagation. Other methods include layering, grafting, budding, root division and tissue culture.

House plants such as flowering maple (Abutilon), Chinese evergreen (Aglaonema), coleus, jade plant (Crassula), dieffenbachia, geranium (Pelargonium), philodendron and pilea root easily from softwood stem cuttings. So do chrysanthemum and carnation (Dianthus).

The stem's condition is a guide to readiness of a cutting. A test-stem should snap when bent.

Softwood stem cuttings should be about three inches long and come from the new, soft, tip growth, usually present in spring or early summer. Cut the stem tips just below the node with pruning shears or sharp knife. Many outdoor shrubs also are successfully grown from softwood cuttings. Remove leaves on the bottom half of the cutting but let a few remain on the top portion.

A rooting hormone is optional for the home grower planting only a few cuttings. Such products contain auxins which stimulate rooting. Dip the cutting's base in the powder. Commercial growers routinely use rooting hormones.

The planting mix for cuttings should be light and porous so new roots can easily grow into it. Mixtures half perlite and half vermiculite or half perlite and half sphagnum peat are excellent. Such combinations keep moisture and are well aerated. Often, sand alone works.

Put the mix in a shallow container with a hole for drainage and put the cuttings in it, with leaves just above the mix. A moist, bright environment is needed.

Add enough water so that it drains through the bottom. Leaves need high humidity to absorb moisture since no roots are present. Commercial growers use irrigation mist systems that turn on at intervals to maintain high levels of moisture and humidity. When working with just a few plants, gardeners can create a humid environment by erecting a plastic cover over the container. Clear plastic wrap used for food storage does the job.

Roots usually become visible in two to three weeks. Some plants take less time, others longer. Test a few cuttings by tugging gently but resist seeing if all grew roots.

Some plants require propagation by semi-hardwood cuttings. These are taken in midsummer or fall, when growth is not as succulent.

Hardwood cuttings are taken in the dormant season and are typically six inches to 12 inches long and the width of a pencil. They are planted for rooting with one or two leaf nodes, or buds, above ground. Roots form at the nodes that are buried.

Once cuttings have adequate roots, transplant them into a container of potting mix. Unless you have many cuttings, it is usually easier to buy a commercial mix. Water thoroughly. After the roots become well-developed in the container, the plants will be ready for transplanting to a larger pot, or outdoors.

For further reading, see "Plant Propagation: Principles and Practices" by Hudson T. Hartmann and Dale E. Kester, published by Prentice-Hall with a suggested retail price of $52. It's a standard college text on the subject.

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