My recent garden exchange experience generates thoughts about the ways in which gardeners share plants and other garden items.

In some Monterey Bay area communities, garden exchanges are infrequent occasions. There are successful events in Monterey and Seaside (and perhaps other communities) that local groups organize once a year. Santa Cruz has a low-key monthly exchange that is popular during the growing season.

Exchanges generally focus on plants as cuttings, bare-root specimens, seedlings (also called “starts”) in four-inch plastic nursery pots, and larger plants in one-gallon (or even five-gallon) pots. Empty pots and sometime other garden items also appear occasionally.

Most gardeners have plants that they could bring to an exchange simply because many good garden plants reproduce naturally and sometimes vigorously. While all plants that grow in a given area can be exchanged, this practice began with “passalong plants,” which are thought of as botanical heirlooms that have survived for decades primarily by being handed from one gardener to another. These plants might not be easily found in garden centers because they reproduce so easily that commercial growers choose not to compete with nature.

One example of such a plant is the Alstroemeria, commonly called the Lily of the Incas. This plant is also called the Peruvian Lily, although they are native to either central Chile (winter-growers) or eastern Brazil (summer growers). Central Chile, as you my recall, has a summer-dry climate very much like that of the Monterey Bay area, so these plants thrive locally.

Alstroemeria in bloom

The Alstroemeria reproduces by creating clusters of small tubers that are easily shared and grown. Plant the tubers horizontally, about eight inches deep.

This plant’s blossoms are available in many shades of red, orange, purple, green, and white, flecked and striped and streaked with darker colors. It produces long flower stalks and is a very good cut flower. To stimulate blossoming, tug the flower stalks instead of cutting them. They release easily.

The Alstroemeria produces large numbers of tubers, so many that it can be difficult to dig into a long-established bed. This growth habit exemplifies the passalong plant: desirable and prolific.

Steve Bender and Felder Rushing wrote Passalong Plants (2002), in which they describe 117 plants that have been shared for many years in the southeastern states. There are at least as many plants that are traditionally shared by coastal California gardeners, including both natives and imports.

I collected two free plants at last week’s garden exchange:

• a seedling Tree Tomato (Tamarillo), a native of Chile that is a fast-growing tree that produces egg-shaped edible fruits with exotic appeal. It could grow quickly to fifteen feet, but can be limited by pruning. I’ll try it in my Chilean bed.
• Mother of Millions (Bryophyllum delagoense), a succulent plant with interesting leaves. It is native to Madagascar that “escaped” to Australia, where is it considered a noxious weed. Each plant produces small plantlets along the edges of its leaves that detach and form new plants. This makes it difficult to eradicate. It is also toxic to humans, pets and livestock. I will not add this plant to my garden. Or share it.

Visitors to the garden exchange also presented a wide variety of other popular plants. These examples suggest that both interesting and troublesome plants might be available, so a brief inquiry on the Internet research is always appropriate before adding an unfamiliar plant to the garden.

The next Santa Cruz Garden Exchange will be at the Eleventh Annual Garden Faire in Scotts Valley, Saturday, June 18^th. For information, visit http://thegardenfaire.org.