In only a few years, busy Lizzie, Impatiens walleriana, went from being one of the most popular warm season annuals to being unavailable in nurseries. It is now making a slight comeback. Most of those planted during their planting season last spring are now so profuse with bloom that their rich foliage is mostly obscured. Although they can be perennial, almost all get replaced in autumn.
The problem associated with their unavailability was that a type of downy mildew that is resistant to common fungicides had become a temporary epidemic among the growers who supply the plants. The disease is still out and about, so can still infect busy Lizzie, but is not such an epidemic after a few years of scarcity of host material for it to infest. Nonetheless, busy Lizzie is still risky.
Bloom is clear and cheery hues of pink, red, magenta, peachy orange, pale lavender and white. The five petaled flowers are about an inch or two in diameter. Leaves are a bit bigger than the flowers. Foliage and stems are succulent and very fragile, so will not tolerate traffic, and will die in winter if exposed to frost. The biggest plants can get almost two feet tall and three feet broad.
This one is no fun to handle. It is just as prickly as it looks. Yet, it is the spiny foliage and blooms that make ‘Big Blue’ sea holly, Eryngium X zabelii ‘Big Blue’, so appealing. The knobby blue thistle flowers are centered on prominently flaring grayish blue bracts that look like metallic snowflakes. The intricately lobed grayish foliage contrasts splendidly with just about any darker green foliage.
It was probably a good idea when it was introduced to California, but fountain grass, Pennisetum setaceum, became too much of a good thing for a few temperate regions in which it naturalizes and displaces native vegetation. Although it now works to inhibit erosion where it grows wild on the embankments of highway interchanges, it must sometime be mown because it is combustible.
The delightfully clear sky blue flowers of blue plumbago, Plumbago auriculata, seem like they belong with colorful annuals or in a tailored border of colorfully blooming perennials. However, the rampant canes of mature plants are really best in the background where they have room to grow wild. The canes do not climb like vines, but can flop over other shrubbery as high as fifteen feet.
It is a common theme. Coreopsis was a much simpler group of only a few specie and cultivars in the 1980s. There are now too many hybrids and cultivars to keep track of. They have been bred so extensively that they do not produce viable seed like the old fashioned types that can self sow so nicely, and were more closely related to the unimproved specie that would be found in the wild.
Once it gets started in late spring, ‘Mystic Spires Blue’ salvia has potential to bloom until autumn. It only needs older floral spikes pruned away as they fade (deadheading) to stimulate new bloom. If it gets overworked and lanky without deadheading, it can be cut back in the middle of summer to start a new bloom cycle all over. It can get more than three feet tall and almost three feet broad.
There are so many more of the fancier cultivars of hydrangea, Hydrangea macrophylla, than there were as recently as the 1990s. Many of the pink and blue hydrangeas were interchangeable years ago. They would bloom blue if the soil was acidic. They would bloom pink if the soil was alkaline. Their color changed accordingly when planted from potting media into soil of another pH.
Compared to crape myrtle, sycamore (London plane) and many other more popular trees, the beech, Fagus sylvatica, is much less problematic, and really deserves more respect. Although it can eventually get almost as big as sycamore, it has remarkably complaisant roots. It is neatly deciduous, defoliating only in autumn, without noticeable floral mess. Disease and pests are rare.
The native American coneflower, Echinacea purpurea, of the Midwestern prairies has been popular within its native range longer than anyone can remember, and has become more popular in the West as extracts of echinacea became a fad in herbal medicine several years ago. Modern garden varieties and cultivars have been bred and hybridized for larger and more colorful flowers.
Pink, red or white are the only choices. There happens to be a darker shade of red. Yellow throats are more conspicuous in white flowers. Otherwise, there is not much variation of color amongst the various mandevillas. The flowers are very similar in both color and form to those of related oleander, but are larger. Some are as wide as three inches. Small flowers can have pointed petals.
