UNITED STATES—Dilemmas are common in gardening. Should summer vegetables that are still producing be removed so that winter vegetables can get started on time? What about replacing summer annuals that are still blooming with winter annuals, and then replacing winter annuals with summer annuals half a year later? Should tender perennials be regarded as annuals, or get a second chance?
Right now, some perennials are looking tired. Many will be going dormant for winter. Many do not get much down time, and will start to develop new growth faster than old growth deteriorates. Not many make their intentions obvious. Deciding how to work with them can be confusing at times. It might take a few years and a few mistakes to get familiar with the habits and lifestyles of some.
If cut back too early, hardy zonal geraniums will not regenerate much until the weather gets warmer at the end of winter. In the interim, they are more likely to be killed by frost without the protection provided by old growth However, some varieties start to grow in winter. If not cut back soon enough, new growth mingles with old, so that they are difficult to separate when they do get cut back.
It is best to observe what hardy geraniums are up to before deciding on when to prune. If they start to develop vigorous new growth down near the ground, the old growth should probably be cut down as far as the new growth. It is likely better to take a chance that they might be damaged by frost. Those that do not start to grow right away can enjoy the insulation of old foliage for a while.
Thoroughly deciduous perennials, like deciduous daylilies, dahlias and some ferns, can be groomed of their deteriorated old growth without risk that they will start to regenerate new growth prematurely. However, cutting back some specie of salvia might actually stimulate development of exposed and frost sensitive new growth. Perennials that get damaged by frost later in winter should not be groomed of damaged growth right away. The damaged material provides a bit of insulation for lower growth, particularly if new growth was stimulated by the damage.
Highlight: African daisy
It seems like not so long ago when the only African daisy that was commonly available was the trailing African daisy that makes such a nice relaxed ground cover for small spaces. The simple white flowers have navy blue centers, and are occasionally joined by mutant light purple flowers. The cultivar that blooms only in light purple was not as popular. Things have certainly changed!
African daisies, Osteospermum, have been bred and hybridized so extensively that most of the modern cultivars are not categorized by specie, some are known by their cultivar names. Most are likely related to Osteospermum ecklonis, which was the first of the shrubby specie to become popular. Although often grown as cool season annuals, African daisies are short term perennials.
Flowers can be various pastel hues of purple, pink, orange, yellow or white. Bloom can be profuse in random phases, and sporadic bloom is almost continuous between early spring and late autumn. It is only postponed by the coolest winter weather and the warmest summer weather. Mature plants can get a bit more than two feet high and wide. They want full sun and regular watering.
Horticulturist Tony Tomeo can be contacted at tonytomeo.com.