GARDENING : NOVEMBER'S RICH HARVEST OF FLOWERING PLANTS.

Byline: Joshua Siskin

Never have so many flowers bloomed in November as they have this year. It's not only the rain, which brings out the best in any plant. It's also the expanding variety of plants that are available, many of which blossom in the fall.

If you would like a border 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 fall border - if not of the spring and summer border, too - are the salvias. (A border is wider and deeper than the average flower bed.) Within the last 10 years 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.

Most of the salvias mentioned here, and probably a lot more, will be on sale today at Pierce College. In a 50th-anniversary celebration, nurseries that the general public may not know about will be selling their plants. These are nurseries that grow unusual plants not carried by most retail plant outlets. In addition, the local bromeliad, fern, iris, orchid and rose societies will be in attendance for anyone with a passion for a particular group of plants. There will also be experts - including Lili Singer and Pierce College professors - available to answer any of your garden questions free of charge. These events are being held from 9 a.m. to 5 p.m. in the horticultural center, just inside the Winnetka Avenue entrance to the college. Exit the Ventura Freeway (101) at Winnetka Avenue and go north. The college will be on your left side. Follow the signs to the horticultural fair and plant sale.

Tip of the week

If you have a problem with a plant, bring in a sample of your ailing specimen to the expert of your choice. A reputable nursery will have someone on staff who can diagnose the cause of your plant's malady, based on a leaf, stem, flower, or fruit sample. Before bringing in your sample, check the condition of your soil. Many problems are caused by soil that is either too wet or too dry.