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Growing Exotic Impatiens Species

Exotic species impatiens are so new to American horticulture that gardeners are often baffled about the best ways to grow and propagate them. Derick Pitman, who has been collecting them for 15 years at his home in Sacramento, California, is one of the most experienced growers in the country.

With few exceptions, exotic impatiens grow best in loose, humus-rich, moist soil and high shade. For hardy species, make sure the soil is well drained, even slightly mounded or higher. In heavy soil, tuberous impatiens, Pitman points out, may rot. Running plants should be given space to spread since they don’t compete well in crowded plantings.

Collecting seeds is tricky, he admits. If you’re not sure, lightly squeeze a pod. They begin to have a translucent appearance when they are close to popping. If they are already ripe, they will explode at the slightest touch, spraying seeds all around. To make sure that doesn’t happen, Pitman places a small gauze bag around the pod or pod clusters, and secures it with a paper clip. When the pod bursts, the ripened seeds will drop into the bag.

Harvested seeds are best sown when fresh. If you must store them, let them dry for about a day, then place them in the refrigerator. Impatiens, Pitman stresses, don’t have a long shelf life and it’s important not to let them dry out too much. If they age past six months, they are probably too old.

The Himalayan species need a period of stratification (not necessarily freezing temperatures) before they germinate. Pitman sows seeds in his greenhouse where he lets the temperature fall to 40 degrees Fahrenheit. In his experience, seeds germinate well under these conditions. In colder regions, sow seeds of the Himalayan species outdoors in fall or spring before the last frost. Sow seeds on the soil surface, because all impatiens need light to germinate.

To make cuttings of perennial impatiens, Pitman inserts them in moistened perlite, covers the containers with a plastic bag secured with a rubber band, then sets them under florescent light at room temperature. Depending on the species, they may start rooting in about a week.

To learn more about Pitman’s work, visit his website at http://www.mrimpatiens.com.

by Jo Ann Gardner