SHRUBS PERENNIALLY SHUNNED.

Byline: JOSHUA SISKIN

For years, shrubs have been going out of style. Flowering perennials have gradually taken their place. This is not because perennials are more durable than shrubs. In fact, the opposite has been true.

A shrub - viburnum, rhaphiolepis, oleander, abelia - is supposed to keep its health and vigor for 30 years or more, whereas flowering perennials - salvias, marguerite daisies, dusty millers, and abutilons - will be fortunate to look good for five years before weakening and ending up on the compost heap.

One of the reasons people do not like shrubs is because of the work involved in their maintenance. Shrubs develop stout, woody stems that must be thinned out on a regular basis, while perennials have softer wood that is easier to prune. Even better, maintenance of perennials typically involves cutting them back to half or less of their mature height.

Perennials generally bloom for longer periods than shrubs or they may bloom on and off all year long. Perennials also are said to have character, with interesting leaf shapes, textures, colors and fragrances, while shrubs are typecast as large, cold, globes of green.

There is another reason for the proliferating prejudice against shrubs: they develop nasty diseases and insect infestations.

Nowadays, when considering plants that grow to a height of 10 to 20 feet, small trees - with foliage from the bottom of their trunks all the way up - may be given priority over shrubs. Several species of Podocarpus, all with lance-shaped leaves, admirably fill this bill. Weeping podocarpus (Podocarpus gracilior) is my favorite of the group, due to its soft foliage and resistance to soil fungus diseases.

Small trees with multiple trunks may also be used as alternatives to shrubs. In this regard, bottlebrush (Callistemon citrinus) and crepe myrtle (Lagerstroemia) come to mind. There are two shrub choices that will have their detractors but, for some, they make the perfect background plants. Tree mallows (Lavatera), some native to the Mediterranean and some native to California, quickly grow to 8 or 10 feet, bloom like crazy for five to seven years or so and then suddenly die; just as these drought-tolerant plants become maintenance headaches, they die.

One of the best all-purpose shrubs for my money is variegated mock orange (Pittosporum Tobira 'Variegata'). This shrub grows well in light exposures ranging from full sun to moderate shade. Its cream and green foliage combines well with plants of every description.

TIP OF THE WEEK: For a hanging basket or container in filtered sun, consider a combination of two ornamental sweet potato vines. Ipomoea 'Terrace Lime' has heart-shaped, yellow-green leaves, and Ipomoea 'Blackie' has the same foliage in burgundy. Both grow to a height of around six inches before trailing.