BEAUTY OF MARMALADE COULD MAKE ANY GARDENER GREEDY.

Byline: JOSHUA SISKIN

Gardeners are among the most generous, least acquisitive people in the world, having absorbed the lesson of ``constant giving without thought of reward'' from their plants. Yet I do not think there is a gardener alive who, upon glimpsing a marmalade bush in full bloom, would not want to possess one.

You see, there is something supremely satisfying about the flowers of a marmalade bush (Streptosolen jamesonii). No flowers are silkier, and none of a purer orange, than these. With huge clusters of fiery blooms at the ends of shiny-leafed shoots, the marmalade bush invariably becomes the focal point of any sun-splashed garden.

The marmalade bush is frost- and heat-sensitive and will grow best when it is somewhat protected from the elements in a partial sun or half-day sun location.

It is a pleasant companion to orange floribunda roses; it blooms from spring to fall and will more than likely be in flower between bursts of bloom from the floribundas. For maximum orange, plant a tapestry hedge that alternates between marmalade bush and orange floribundas such as ``Livin Easy'' and ``Judy Garland.''

In response to a recent column on color gardens, I received a letter from Jan Winning of West Hills with the following wisdom on keeping constant color:

``The trick is to keep trying. When something works, use it again, and don't try to plan anything. Let the plants do it for you. They know when they're happy, and there's nothing one can do about it.

``I constantly experiment. One area of my garden gets a consistent freeze in winter and, because of the sun's movement, gets hot, late-afternoon sun in summer. For this area, I use Rhaphiolepis, orange bush lantana and daylilies. I interplant with annuals and can maintain all-year color.

``After years of adding planter mix and amendments, I have changed to adding bags of top soil. Most of the top soil comes with amendment anyhow, and it all doesn't disappear with watering.''

I strongly support the idea of using topsoil as an amendment, especially in improving the heavy soil found in much of the West Valley.

Q: I have a deciduous oak tree that the landscaper has put dirt around to prepare for sodding the lawn. Around the tree, six to 12 inches of dirt have been added above the original soil level. It looks healthy now but I've been cautioned by some that the tree will die unless I remove the dirt. What would you suggest?

- Tom

A: It is not a good idea to change the soil level around trees of any kind. If soil covers up any part of the trunk, the tree will probably die.

As a general rule, oak trees established in nature or in nonirrigated landscapes can be adversely affected by the sudden presence of a lawn and the increased water that comes along with it. Most of the oaks planted in California that grow in lawns are evergreen, not deciduous like yours. Find out what species of oak you have before deciding what to plant, or not to plant, around it.

TIP OF THE WEEK: As the spectacular spring bloom of roses comes to an end, now is the time to put down slow-release fertilizer. It lasts for several months and its large spherical granules make it possible to know at a glance when it is time to fertilize again.