GARDENING : GARDENS THAT WILL LIVE ON IN THE NEXT MILLENNIUM.

Byline: Joshua Siskin

By now, almost every subject on earth has been discussed in millennial terms, so why not consider the millennial garden?

Actually, if you were looking for a location to plant a garden that would last for a thousand years, you could find no better site than the well-drained, alkaline soil of certain selected Valley locations. In the East Valley, such soil is found in parts of North Hollywood and Toluca Lake, and in the West Valley it is encountered in parts of Reseda and Woodland Hills.

Many of the plants in the world that are more than a thousand years old grow in well-drained, alkaline soil in climates as dry, or drier than our own.

Not until 1953 were the oldest trees in the world identified. The identification came from a dendrochronologist, Edmund Schulman. Dendrochronology is the science that dates environmental changes from the study of tree rings.

Schulman made an expedition to the White Mountains of California, just above Death Valley, and there found a stand of ancient bristlecone pines. A technique called core sampling allows the scientist to extract a very thin core of wood through the trunk without damaging the tree. The oldest bristlecone Schulman discovered, which he named Methuselah, is more than 4,700 years old. The tree is growing in pure dolonite, a highly alkaline calcium-magnesium mineral. Although this oldest tree gets only about 10 inches of rain a year (four inches less than the annual average rainfall in the Valley), the dolomite in which it is rooted holds moisture well and also reflects sunlight quite efficiently, keeping Methuselah's roots cool. There is a take-home lesson here for gardeners: A plant lives up to its potential when its roots are kept cool, which is an excellent argument for putting an insulating layer of mulch - be it leaves, straw or compost - on the soil surface throughout the garden.

There are two other trees from dry climates that can live upward of 1,000 years and could be planted in Valley gardens, whether in the ground or in patio containers. The olive tree will happily live 2,000 years or more as long as it is allowed to grow on rainfall alone. Another hydrophobic tree with a life expectancy in the thousands of years is the dragon tree (Dracaena drago). The dragon tree, a relative of both yuccas and agaves, has attention-grabbing, Medusa-like blue-gray leaves atop its fibrous trunk or trunks. It cannot help but become a major focal point in any garden in which it is planted.

Redwoods, unlike the trees mentioned above, do appreciate a somewhat moist and misty climate. In the Valley, redwoods grow best when they are completely protected from direct summer sun. One way of taming redwood trees is to bonsai them and create your own miniature forest in a dish.