UNITED STATES—Seed is the most familiar source of much of the vegetation that inhabits home gardens. It is the origin of almost all vegetables and most annual flowers. Some seed grows directly into its gardens. Some grows in nurseries to become saleable young plants. Seed is not the only method of propagation though. Cuttings, division and layering are as productive.

Cuttings, as well as divisions and layers, are genetically identical to their single parents. Unlike seed, which are products of two parents, they lack potential for genetic variation. Division is the separation of stems with roots from perennials or clumping woody plants. Layering is the rooting of stems by partially burying them while attached to their parents.

Cuttings grow simply as pieces of stem within moist rooting medium such as potting soil. They initially lack roots and perhaps foliage. They develop new roots and foliage as they grow. Their medium must remain moist throughout the process. For many plants, rooting hormone accelerates root initiation. Some species can grow roots as they soak in water.

Various propagation techniques accommodate a variety of species.

Hardwood cuttings are mostly from deciduous species as they defoliate for winter. Those from last winter are developing now. Evergreen hardwood cuttings retain some foliage through their winter dormancy. Softwood cuttings can be either deciduous or evergreen. They involve fresh new growth, so they can begin as soon as such growth is mature enough.

The lower cuts of cuttings should be just below a node. Upper cuts should be just above a node. Terminal cuttings are tips of stems without upper cuts. Each cutting must include at least two good nodes. Some species may need cuttings to be several inches long in pots. Most grow better from small cuttings that fit into flats. Some can go directly into a garden. Cuttings should lack leaves below the level of their rooting medium.

Softwood cuttings generally require humidity to help compensate for their lack of roots. Most also appreciate partial shade. Evergreen hardwood cuttings appreciate the same as weather gets warmer and drier. Warmth from a heating mat below pots or flats might accelerate rooting. Many species are difficult or impossible to grow from cuttings though.

Highlight: Martha Washington Geranium

Mrs. Washington never grew Martha Washington geranium, Pelargonium X domesticum. It was hybridized in Europe from south African species after she passed away. Although classified as a hybrid species, it is actually a group of distinct hybrids. Most are related to the same pair of primary ancestors. A few other species mingled in the process though.

The largest cultivars do not get much taller than three feet. Some develop rather irregular form. A few grow upward only to fall over. Minor tip pruning can improve awkward form. Stems are woodier than those of common zonal geranium. Consequently, cuttings do not develop roots as efficiently. Old specimens are less likely to recover from major pruning.

Martha Washington geranium may not bloom quite as profusely as zonal geraniums. The flowers are more spectacular though. Floral color can include purple, lavender, pink, red, burgundy or white. Billowy flowers are bordered or blotched with alternate colors. A few flowers bloom together on rounded umbels. Evergreen foliage is light green and ruffly.

Tony Tomeo can be contacted at tonytomeo.com.