Propagation by rooting cuttings is still the most efficient form of propagation for many species that are easy to root, such as jade plant or geranium, which can simply be "stuck" directly where new specimens are desired. Those who have a greenhouse where heat and humidity can be optimized may prefer to root cuttings of a few other less-cooperative species or trees that lack limbs near to the soil that can be "layered." Nevertheless, if only a few copies of a specimen are desired, layering is still perhaps the most reliable form of propagation and certainly does not require the attention demanded by rooting cuttings.

The simplest layering involves rooting a stem directly in soil while it is still attached to the parent specimen. For example, when I wanted a single additional specimen of English holly, I found a stem on one of the established specimens that could be bent downward so that a few inches of the stem length could be buried adjacent to the parent with the few inches of foliated stem extending above the soil beyond the buried section. Before burying the stem, I cut partially through it to inhibit vascular sustenance from the parent specimen and to encourage vascular independence. The cut was approximately two thirds of the way through the stem and located on the buried section of stem.

The cut should be on the underside of the stem so that it is held open as the stem is bend downward to be buried in the soil. Some people prefer to wedge a small pebble into the cut to ensure that it remains open. Rooting hormone rubbed into the wound promotes rooting of most species. I prefer to bury a few inches of stem beyond the wound, but most roots actually emerge from the wound rather than from the bare stem. Prior to rainy weather, irrigation is important.

Stems layered now should be sufficiently rooted to be pruned from the parent in summer. Most species develop undifferentiated "callus" growth around a buried wound through winter with a few roots, but produce more roots as vascular activity resumes in spring. The "umbilical cord" stem may be pruned completely away from the parent specimen, and away from the copy where roots have emerged. The rooted copy can then be installed elsewhere in the garden.

Flower of the Week: Scottish crocus

Crocuses were perhaps the first bulbs I became acquainted with, as they emerged in the early spring around my mother's fruitless mulberry tree when I was about 4 years old. My mother explained that they were the first flowers to appear through the melting snow in a mythical land beyond Santa Clara County known as Pennsylvania. Of course, I had absolutely no experience with snow on Fenian Drive and did not understand why emerging crocuses caused it to melt, but had learned to identify the bloom of the crocus with the arrival of spring.

However, Scottish crocus, Crocus biflorus, naturally exhibits such extreme genetic variability that some bloom during autumn instead of spring. Those selected as a variety of "autumn-blooming crocus" are nearly indistinguishable from those that bloom more traditionally during spring, but naturalize more easily and bloom more reliably during subsequent autumns. This species includes various subspecies and hybrids as well.

The thin leaves emerge to approximately two inches and are almost immediately followed by white blooms with yellow centers. Purple stripes visible on the outside of floral buds fade and are obscured as the flowers open and the petals fold back. Scottish crocuses are not often found in nurseries, but may sometimes be obtained from the gardens of friends, where they have become naturalized.

Horticulturist Tony Tomeo can be contacted at 408-358-2574 or at LGHORTICULTURE@aol.com.