Mums - or chrysanthemums to be botanically correct - start showing up in garden centers around the end of August, their still-closed buds waiting to open when you get them home. The flowers come in all sorts of shapes - pompon, daisy-like and spider -and all colors, except blue.

You can use mums in the garden, in containers or even in hanging baskets and window boxes. For visual impact, group them together instead of stringing them out, one by one, between other shrubs. Bushel baskets, wheelbarrows, barrel-type planters, urns, large bowls and huge clay pots are good for multiple plantings. Just be sure to plant container mums in the ground before winter.

Pots of fall mums also can be used to create a fall scene in your front lawn or garden. Decorate a bale of straw with a scarecrow made from old clothes, some decorative Indian corn and cornstalks and a pumpkin or two. Group some potted mums around the straw bale. A decorative turkey can be added later for a Thanksgiving theme. The entire family can get into this decorating project.

Mums may be today's vogue way to dress up the fall garden, but their popularity actually goes back 2,500 years. For centuries the chrysanthemum was the crest and official seal of the emperors of Japan. Even today annual chrysanthemum festivals are celebrated throughout Japan each fall, much like the Oktoberfest in Germany. Often you'll see life-size chrysanthemum dolls made entirely of mums at the festive events. Mum designs also have been used to decorate many costumes in Japan, especially the obi, or sash, worn with the country's traditional kimonos.

Chrysanthemums were introduced to North America from Europe in 1798 by John Stevens, a nurseryman in Hoboken, N.J. The ``Golden Flower of the Orient'' was established in the United States by 1850, and the Chrysanthemum Society of America was founded and held its first exhibit in 1902. Back then mums were strictly fall-blooming flowers, but greenhouse science has turned them into year-round flowers for all occasions.

Those pot mums flaunting their finery in florist shops throughout the year are florist mums, which have been raised in greenhouse conditions that simulate the short days of fall that make them flower.

You can let them do their blooming, then plant them outdoors to enjoy for many more years.

MUM SOCIETY

The National Chrysanthemum Society publishes a quarterly journal, beginner's handbook and variety of growing tips and information on mums. Write: National Chrysanthemum Society Inc., Galen L. Goss, secretary, Dept. HRG, 10107 Homar Pond Drive, Fairfax Station, Va. 22039-1650.

MUMS AT A GLANCE

COMMON NAME: Hardy chrysanthemum - or mum

SPECIES: Chrysanthemum (kris-an'the-mum), part of daisy family.

FORM: Shape varies according to variety but usually many-branched stems; forms range from low, spreading cushion mums to tall, narrow upright ones.

SIZE: 1-4 feet tall, 18-24 inches wide.

EXPOSURE: Full sun to partial shade, need at least six hours of sun each day for maximum growth and flowering.

LEAVES: Deep green, alternate leaves, usually dense; strong-smelling foliage.

FLOWERS: Blooms come in lots of colors - red, yellow, bronze, lavender, pink, purple, white - and take many forms: pompon, daisy-like, single, double, button, spoon, semidouble, and spider. Flower sizes vary from one inch to more than 6 inches.

VARIETIES: Too many to list in early- and late-blooming varieties and colors. McDonald Garden Center has its own variety called the Dream World mums, which are self-branching and don't need pinching. Most local garden centers carry mums by Yoder, one of the largest producers of garden and pot mums in early- and late-blooming varieties. You'll find Yoder mums at places such as Smithfield Gardens in Suffolk, Anderson Garden Center in Newport News, London Bridge Greenhouses and Nursery in Virginia Beach and White's Nursery &Greenhouses in Chesapeake, to name just a few.

FLOWERING TIME: August-November. Local garden centers are carrying late-blooming mums so homeowners can have them blooming into November. Garden mums are short-day plants, meaning they flower when the days are shorter in the fall. Pot or florist mums are grown under greenhouse conditions that simulate short days. Florist mums can be planted outdoors after they bloom.

CULTURE: Plant in rich soil, high in organic matter with good drainage. Water regularly. Garden mums planted outdoors in the fall don't need feeding until spring when they start growing. Use a 5-10-5 at the rate of 1/2 to 1 pound per 100 square feet; repeat monthly until August. Liquid fertilizer also can be used; or use a time-release fertilizer so repeat feedings aren't needed. Young mums planted in the spring should be spaced 18-24 inches apart so they have room to grow.

USES: Bedding plants, hanging baskets, patio plants, window boxes. For the landscape, group three to five together for drama. Plant early- and late-blooming ones so you have color until time to decorate for the holidays after Thanksgiving.

PINCHING: Most garden mums need pinching to encourage branching and development. Pinch back garden mums in the spring as soon as new growth is 4-6 inches tall. Use your thumbnail and index finger to remove or ``pinch'' abut half of the new growth at the top of each and every shoot. Or, simply use clippers and keep the growth cut back 4-6 inches until mid-July; the result will be a nice mound effect come fall.

WINTER PROTECTION: Keep mums moist as winter nears. There is no need to prune back plants until spring. Mulch the plants; in the spring remove old stems and rake back the mulch.

PROBLEMS: Aphids, scale, mites, slugs; bacteria, fungal and viral diseases.

RELATED SPECIES: Painted daisy, Shasta daisy and Nippon daisy.