IN THE GARDEN `DIAMOND FROST,' THE PERFECT POINSETTIA PARTNER.

Byline: JOSHUA SISKIN

Just when you were wondering what flowers you could place around your poinsettias without overdoing it, along comes a botanical relative to serve as an eminently suitable companion plant.

You would not want to surround poinsettias with something that would try to compete with their brilliant scarlet foliage. Yet a plant more refined and understated would be quite welcome, a selection that would provide relief from the relentless riot of red.

Enter Euphorbia ``Diamond Frost,'' the perfect foil for a poinsettia (Euphorbia pulcherrima). ``Diamond Frost'' has delicate white flowers that will remind you of baby's breath (Gypsophila paniculata). The difference is that Euphorbia ``Diamond Frost'' is grown as a potted plant for both indoor and outdoor use. ``Diamond Frost'' has been available in the nursery trade for only a few years, yet in this time it has proven itself from Riverside to Santa Barbara. In these locales, planted outdoors, it blooms nonstop when utilized as a bedding plant or ground cover. In one instance, in the space of six months it grew from a 4-inch pot into a 3-foot-tall by 4-foot-wide, continuously blooming, botanical juggernaut. On the coast, it has thrived in full sun, while requiring some sun protection in hotter inland areas.

``Diamond Frost'' is highly drought tolerant with a bushy, yet open growth habit, uniquely qualifying it as a subject for hanging baskets. Many plants are recommended for hanging baskets, and they fulfill that role admirably for a short time. Yet they often fade soon enough, or become leggy, and certainly do not flower for long.

Hanging basket

The problem is that suspended in the air, they dry out quickly and seem perpetually in need of rehydration. ``Diamond Frost,'' as a member of the succulent Euphorbiaceae or spurge family, is not as hung up on the issue of moisture loss. A bonus attached to ``Diamond Frost'' is its ease of propagation so that you are actually getting dozens, if not eventually hundreds, of plants at no extra charge. Detach 3-inch stem pieces and stick them in pots or soft ground to expand the presence of ``Diamond Frost'' in your garden.

The colorful castor bean

If you were compelled to design a garden that included members of the spurge family alone, the result would be a diverse collection of unusual-

looking species with brilliant colors and exotic foliar shapes, united only by their minimal water requirement and their allergenic-to-poisonous sap. Castor bean (Ricinus communis) is the deadliest spurge -- and perhaps the deadliest of all plants. Its large, sawcut leaves which, depending on the variety, are lime green, bright red, crimson, bronze or purplish-black, impart a dramatic ethos you won't soon forget. Castor bean is sought out by people who, while living in mild winter areas like our own, still desire foliage that turns colors during the fall season.

Another spurge that changes color this time of year is Chinese tallow tree (Sapium sebiferum), one of the most desirable small- to medium-size ornamental trees. In my humble opinion, it deserves equal billing with the crepe myrtle as a street tree for our city. Its luminescent leaves are currently shimmering in red, bronze and gold. A Chinese tallow tree has been planted in Sherman Oaks just east of Woodman Avenue, along Ventura Boulevard.

`Crown of Thorns'

Euphorbia millii ``Crown of Thorns,'' which shows off reddish bracts -- modified leaves that look like flowers -- throughout the year, is available both as a compact, cushiony dwarf and as an upright, branching thorn bush that eventually reaches a height of nearly five feet. You can also find it with pink and occasionally yellow bracts.

Frost-sensitive snowbush 

There are many other spurges worth planting but none with more interesting foliage than the semi-tropical snowbush (Breynia nivosa). Leaves are variegated in cream, pink and green. Because it is cold-sensitive, snowbush should be planted close to a structure or under an overhang or tree in order to be protected from frost.

TIP OF THE WEEK: One of the toughest indoor spurges, which may even survive occasionally on a well-enclosed outdoor patio, is croton (Codiaeum variegatum). Croton is that plant whose waxy, variegated leaves are colored in bright green, yellow, and red. It needs good light to show its colors, so make sure you place it either next to a window or below a skylight.