IN THE GARDEN FINDING PERFECT SPECIES FOR PLANTERS.

Byline: JOSHUA SISKIN

Deciding what to put in a courtyard planter can present an interesting conundrum.

Found in most apartment buildings and multistory condominium complexes, courtyard planters have much in common, exposure-wise, with certain patios and balconies of people who live in houses.

Although sky and therefore fall they fall under the category of exterior gardens, the conditions of restricted or low light and poor air circulation in a courtyard mimic those of the indoors.

The most durable plants for courtyard planters tend to be succulents, low-growing and multi-trunked palms, house plants, and shade-tolerant species of all types.

I think that the jade plant (Crassula argentea) must be the most versatile and dependable succulent you can find. It does well in both sun and partial shade, grows slowly with a bare minimum of water, and flowers with dense sprays of white or pink flowers in later winter and early spring. It has a ground cover cousin (Crassula multicava) with similar properties.

Some people think of jade and other shrub and ground cover succulents as unspectacular, if not boring. Yet no one could quibble with the sculptural majesty of arboreal succulents such as tree aloes, blue yuccas, bottle palms (Beaucarnea recurvata), and blue-skinned Cereus cacti. If you wish to surround yourself with living statuary, consider somee of these.

A number of low-growing, multi-trunked or clumping palms will do well in medium to low-light courtyard planters. Mediterranean fan palm (Chamaerops humilis) can take the most sun, followed by the pygmy date (Phoenix roebelinii).

For less light, start with the bamboo palm (Chamaedorea Seifrizii). Consider also the lady palm (Rhapis excelsa) and, for the lowest available light, choose the Kentia (Howea Forsterana).

Quite a number of house plants can successfully cross over from interior to exterior landscaping, especially in cold-protected courtyard locations.

One of the best arboreal crossover candidates is the Madagascar dragon tree (Dracaena marginata). The thin, highly ornamental foliage of this plant often has red margins. As it grows to its full height of 12 feet, its gray branches curve in artistic formations. Here, I cannot continue without mentioning the dragon's blood tree (Dracaena draco), so-called because of its red sap. This is the most durable of all Dracaena species, forming several mop-headed and stocky branches and, a longevity champion, living up to several hundred years in its Canary Island habitat. You can grow dragon's blood in the Valley with half-day sun.

Cast iron plant (Aspidistra elatior) and snake plant or mother-in-law's tongue (Sansevieria) are indestructible indoor plants that tolerate less light than any other species and may be successfully cultivated in shady courtyard planters. Rivaling them for shade tolerance are the Hawaiian elf umbrella tree (Schefflera arboricola) and lily turf (Liriope muscari).

Two other indoor/outdoor choices are the umbrella flat sedge (Cyperus alternifolius) and the airplane or spider plant (Chlorophytum comosum).

These plants will thrive in partial sun to shady exposures, in any type of soil, with a little or a lot of water. If you have a spot where nothing will grow, try one of these plants. There is a caveat here. Once either of these has gained a foothold, it will not tolerate any competition, so make sure the area where either species is planted is dedicated to it exclusively. Each of these, if damaged from weather or from neglect, can be cut down to the ground with confidence that it will rejuvenate itself in short order, more vigorously and decorous than ever before.

TIP OF THE WEEK: Michael Kappel, the gardener with the severe spinal cord injury whom I wrote about last week, grows many of his plants from seed. "It gives me comfort to see this miracle," he says. He harvests his own lettuce seeds, selecting out the most heat-resistant plants for collection.

Some of his seeds, like asparagus and tomatoes, are planted in peat pots and the seedling in the peat pot is transferred directly into the ground to minimize transplanting shock. "You have better success growing seeds in peat pots," he advises, "since soil diseases may prevent seeds from germinating or kill seedlings soon after they sprout." Peat pots are available in most nurseries.