Star Clusters and Other Fall Garden Delights

star clusters (Pentas lanceolata)

star clusters (Pentas lanceolata)

If you would like a perennial fall flower bed of red, pink and lilac colors, grab hold of star clusters (Pentas lanceolata) and wrap ribbon bushes (Hypoestes aristata) around them. True to their name, star clusters produce inflorescences of many small five-pointed stars (“penta” means five in Greek). Star clusters are usually available in red or pink, but may also be seen in white.
The ribbon bush is covered with lilac ribbons and has the additional benefit of self-sowing in the garden.
The gold and silver chrysanthemum (Chrysanthemum pacificum) has become a popular fall-blooming ground cover. Its flowers are fringed gold buttons, and its leaves are edged in silver, giving it year-round interest. The popular florist’s chrysanthemum (Chrysanthemum morifolium) is a perennial that – planted in the ground – blooms during this season, but, through manipulation of light exposure in greenhouses, may be brought into flower at almost any time. It’s the one you see at Ralphs and Vons with the big yellow, bronze, white or violet pompons; through judicious pinching of developing flower buds, the blooms that appear are much larger than they otherwise would be.
Both of the above species of chrysanthemum are susceptible to white rust, a deadly disease that appears as white specks on leaf surfaces. Eventually, large pustules form on leaf undersides. This condition is brought on by excessive rain or humidity.
Affected plants should be destroyed to prevent spread of the disease.
The pride of the perennial fall flower bed – if not of the spring and summer perennial bed as well – are the salvias.
Within the past decade or so, salvias have gained recognition for their long bloom time, their aromatic, sticky and colorful leaves, and their diverse growth habits. Many have a low water requirement.
A number of salvias have arching stems that end in long, curving flower spikes. Among them are Salvia involucrata with 12-inch flower wands in pink and white; Salvia leucantha with velvety purple and white blooms; Salvia bicolor with unusual deep blue and white triangular flowers; Salvia uglinosa with long, sky blue inflorescences.
A low mounding plant native to California is Salvia sonomensis.
Its leaves have a bronzish purplish cast, and its flowers are azure blue. Salvia apiana, another California native, has distinctive white leaves.
Q. My father has an avocado tree that is about 30 years old and produces abundantly. However, it never had so many leaves falling as it did this year, mostly in the spring. Also, one limb has an area 6-8 inches long that is covered with white, spongy type spores. Would this be something that needs attention? Who should I contact?
– Chris Woolley, Sherman Oaks
A. Regarding the disease you mention, it sounds like Dothiorella canker, a bacterial disease that is not a threat to mature avocado trees. As for defoliation, it is not unusual for avocado trees to lose their leaves and does not necessarily mean the tree is at risk. You should, however, cut back on or withhold irrigation until the tree stops shedding leaves. The most dangerous disease where avocado trees is concerned is phytophthora root rot, but in that case leaves would wilt before dropping off. You might want to call National Pest Control, located in North Hollywood, since they are the local experts in the area of plant pathology and treatment.
Q. My blue potato bush is suffering from I know not what. It is losing its leaves and shows very sparse growth. I gave it blood meal about a month or so ago, but that didn’t perk it up. I have been deep watering it, but that does nothing. Its foliage, formerly dark green, has a lime green color. Do you have a recommendation?
– Sonia Draper, Chatsworth
A. Blue potato bush or Paraguay nightshade (Lycianthes rantonnetii) is one of the most confounding ornamentals you can grow. Having observed it for many years, I have concluded that it grows best when it is ignored. It is most majestic when allowed to reach its natural height of 6 to 8 feet. It will cover itself with purple pinwheel flowers and lush foliage for a period of months and then, as you describe, turn pale green and lose its beauty. But just when you think it’s about to die, it starts getting pretty again. In any case, keeping it pruned in the shape of a Tootsie Roll pop is not a good idea. This will lead to its early demise. If you just let it grow, pruning only to keep it somewhat in bounds, it will last for years.

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