July 1 1998 12:00 AM

From wildflowers in a field to day lilies along a country lane to shrub roses on a trellis to a cutting garden near the house, nothing is more prized in the landscape than flowers. Growers provide the designer with abundant choices as to kind, size, shape and color of flower. Annuals, perennials, bulbs, shrubs, trees and cacti - we're fortunate to live in a time and area of the world where our choices are so varied. But with so many choices available, confusion rather than harmony is often the result. Where our designs should complement the built environment, too many of us still waste our client's money. That's easy enough to do when the sun shines.

But design problems really multiply when the sun goes down. On one hand, the nightscape provides an unintended advantage - darkness hides our mistakes. Pansies failing from too much water, drooping beneath the uplights, are in the shadows and no one sees them. On the other hand, a design that works well in daylight may lose its punch under spotlights. That's the first design consideration to be addressed. We need to ask and answer the question, when will the design be seen?

Most landscaped areas are for day viewing. Some are for day and night viewing. Few areas, such as enclosed courtyards near spas or small atria in patio homes are exclusively for night use. If you?re designing an installation for a dual-use area, it?s inevitable that some of your daytime pizzazz will be lost at night. If your site is strictly for viewing under the lights, you can adjust your plant palette accordingly.

After determining the "when" of the design, we consider the "how". For the dual-use landscape or the nightscape, the designer then needs to decide on the source of the lighting. Is it above? Diffused? A spotlight? An up-light? Flowers that reveal their colors in a diffused light are going to fade in a bright spot. Flowers near foot lights along a sidewalk are washed out, those at a middle distance look more true-to-color, those further away begin to disappear in shadows. The point is to recognize that different colors have ranges of effectiveness based on their proximity to available light. That?s due to the nature of light and color.

Color Theory
Daylight is essentially white light. White light is the combination of all colors of the visible spectrum. Color is revealed when pigments absorb some colors but reflect others. The intensity of light affects the colors we see. Flowers in a harsh light must have intense color to be seen - pastels fade at noon, red roses shine. In dim light the reverse is true - pastels reflect more of the available light thus shining like tiny bulbs, while deep colors absorb the available light and their color disappears. Look at impatiens near a footlight. Deep reds, though directly under the light, will be less visible than pinks ten feet away. That's because the pink is reflecting more of the limited available light. As designers, we use the scientific explanation of the quality of light to specify flowers we use in the nightscape.

Design Guidelines
Keep it simple is always a sensible design maxim, so stay away from the 'mixes.' Nothing says amateur more than a hodgepodge of colors. Leave the mixed flats to the home gardeners. Professional flower installations should show that someone has put thought into the project, particularly at night where random acts of planting are a waste of effort. We owe it to clients to pay attention to their problems and to spend their 'color' dollars wisely.

Tend Toward The Monochromes
Monochrome color schemes take advantage of a close range of hues adjacent to one another on a color wheel. If you don't have or know what a color wheel is - how can you call yourself a professional designer? Tsk. Tsk. Hues are the variations, tints, shades of one (mono) color (chrome). At night, monochrome color schemes should tend in particular toward the pastels. Pastels are colors with white added. Of course, there are designs that run all over the color spectrum and are very appealing -- for every design rule there are exceptions -- but for every successful "riot of color" installation there exist a hundred failures. Whether you're designing a day or nightscape, strive to limit your color palette. I like to mix pink and red geraniums, with red and pink roses, with coral colored day lilies and white alyssum. At night, though the reds have essentially flattened in color -- muted by the darkness -- the pale pinks and the whites remain. It's a simple color scheme but it works well in sunlight or nightlight.

Be aware of yellow. Like red, yellow is a primary and 'hot' color with a great deal of pigment. And, it's the most available color in the flower spectrum. But its very availability makes it less noticeable to the eye, and though full of pigment, yellow appears white-ish in limited light. That's okay as long as you are going for that effect and you've anticipated the loss of yellow color. Narcissus is a great bulb. The tiny, light-yellow flowers are that small voice you have to strain to hear. But planted in bunches, their beauty is outstanding. Try them 'naturalized' -- six in a clump, then four, then five, then eight, etc. Random is the rule.

So many flowers, so little time
Impatiens- Impatiens are a special breed. They are the most commonly used bedding plants. Homeowners use them in broad 'mixes' but professionals can show their design savvy at night, by using the newer pastels available on the market.

Growers produce varieties in mottled pinks, pale pinks, pale lavenders and other soft pastels. And the white impatiens are under-used, particularly in nightscapes. Imagine white impatiens, white roses, white calla lilies and alyssum in an enclosed patio outside someone's bedroom. Seen in nightlight, each flower is a mirror reflecting the available light.

Vincas- Vincas resemble impatiens in their flower shape and availability in pastel shades. Be different -- leave the impatiens completely off your jobs and use vincas where conditions allow. White vincas can also substitute for white impatiens, and they take the heat.

Petunias- At night, use white petunias in broad groups. For dual-use (day and night), drop in 15 to 20% of another color. That's the famous 20% rule. In any plant massing design, where color is the primary consideration, add 15 to 20% of another color, no more, no less. Use a contiguous color on the color wheel, or a complementary color will also work. Mother Nature employs the 20% rule; in fact, she invented it so we can, too.

Pansies and Petunias- Here's another common bedding flower where opting for the wrong 'mixes' will mess-up the garden path. Under nightlighting, use the softer pastels -- mottled pinks, faded grapes or whites. There are also yellows that can be grouped with whites. Add the deeper colors - vermilions, violets, rose (20% rule) -- for daytime highlights. Yellow day lilies, calla lilies and while roses work well with the pastel yellow pansies for a yellow monochrome design. The yellow colors will fade at night but the flowers themselves won't disappear from the viewer's radar screen. Petunias share some visual characteristics with pansies and can be used in a similar fashion.

Bluesare tough. More designers are using blue flowers in monochrome schemes. Many are well done. In nightscapes however, recognize that the blues will not retain their true color. If an area is strictly or primarily intended for night use, maybe it's best to avoid blue schemes completely. Failing that advice, agapanthus is usually a plant to avoid because it's so common, but in a nightscape where the blue or white flowers are viewed from a distance, their size and hardiness are hard to beat. The same with Limonium (Sea Lavender). It's another tough cookie, particularly seaside. Iris is available in many shades of blue-violet, and Iris pailida 'Varigata' (Zebra Iris) is an interesting choice because when the flowers have gone the leaves remain a striped green and creamy color. It?s a double-duty winner in the nightscape. True geraniums (geranium himalayense and macrorrhizum) are blue and pale violet respectively. (Geranium sanguineum is a true geranium pink in color). Consider also Spanish lavender, bluebells (Scilla) and campanula, or ceanothus and echium if space allows. Just remember that blue is a component of green. Blue flowers are going to be harder to discern against green foliage when less light is available. Designer Beware.

Yarrow- Achillea is a favorite perennial too rarely planted. Its foliage is fine textured, abundant, gray to green and flowers are available in many colors. I use Cerise Queen in mass plantings. The flower is rose pink, striking during the day. At night, small white clusters in the field of pink act like highlights calling attention to this beauty. Other colors suitable for nighttime are Lavender Beauty, White Beauty, 'Hoffnung' or 'Taygetea' (pale yellows) and Lachsschonheit (salmon). Achillea x wilczekii is white with grey foliage, the flower blending into the background.

Armeria- Who can resist the tiny pink flowers of Armeria maritima? Salmon Beauty has coral pink buds, welwitschiis are pale pink. Plant them as edging for the effect of their wee bit of glow, and contrast their size with Allium, Curly Chives.

Vines- Bouganvillea shines during the day but how to use these bright colored bracts at night under lights? Try Rosenka. It's low-growing, pink tinged with gold. The gold may fade after sundown but the pastel will reflect the light. The same is true of Blush -- its soft, subtle colors may disappoint those used to bolder bouganvilleas, but give it a chance in the right location and its charms will win you over. Try it against a dark background. Want romance? Trachelospermum jasminoides may not sound romantic to your clients, but tell them you're proposing Star Jasmine for a wall in their backyard and they'll feel more reassured. Abundant tiny white flowers on pale new growth, and that wonderful scent sneaking up on them in the moonlight, will make spa time memorable. Just don't plant too much of it. One staked five gallon per job should be the legal limit.

Begonias- Begonia is another good candidate. Specify one with a light flower (White Richmondensis) and the delicate buds have the limited quality seen in a narcissus flower. The red-flowered varieties violate the color rules to show up nicely in the night lights. The contrast of the paler red flower against the much darker leaves seems to be what gives them night life.

Roses- The Fairy is a low, dense shrub rose with abundant, small pink flowers. It blooms forever and takes abuse. What more do you want in a rose? Other pinks are Cecile Brunner -- a climber, and Francis E. Lester -- a pink and white hybrid. Whites include White Banksia, Iceburg -- available as a floribunda or climber, and Sea Foam -- a shrub/ground cover.

There are literally hundreds of other flowering plants (A as in Aster to Z as in Zephyranthes) we can use at night. The thing to keep in mind is the basic idea that light colors and whites will reflect more of the available light. And keep your eyes open. See what other designers have done as you are out and about at night - which flowers are working in an installation and which ones aren't. Nothing improves a designer?s technique more than learning to be observant. We don't have to reinvent the wheel to be an asset to our clients, we just need to be aware.

Nightscape is a Trademark of Nightscaping/Loran, Inc.