Perennial plants and flowers come in virtually every shape, size, color and texture. As you observe the natural landscape, these combinations come into play without even realizing it. As we plan our gardens, perennials are the plants of choice to fill in those lower and mid layers with whatever form, color and texture desired. They are what ties gardens together in a pattern of rhythm, balance and even punctuation.

As you work with perennials in landscape or garden design, keep in mind a few important guidelines to ensure a great looking and vibrant, long lasting garden.

First, know the growing conditions for the area in which you want to plant. A perennial requiring full sun and well-drained soil will languish in a shady or boggy site, so plan accordingly. Conversely, a plant that prefers shade will appear washed out and stunted when grown in full sun.

Next, pick plants that are suitable to your climate. A perennial that's hardy in Zone 7 may die in Zone 5, so do your homework first and make sure the plants are suited for the region or even microclimate. If you're unsure, call your county extension service office. The people there will be happy to assist you with appropriate choices and varieties for your climate.

As you lay out the garden, plan for the tallest plants and flowers to go toward the back of the border or center of the bed, assuming you have access around the bed. Then plant out from there, layering down, so that the shortest plants are in the front. The best landscape designs use this technique. It allows the garden to appear full, while showing off as many plants as possible.

Although perennials are beautiful when in flower and can make for a stunning display, the blooms last only a couple of weeks in many cases. So plan ther design around form, texture and color of the foliage. The best-looking designs incorporate diversity, and this is where form and texture really come into play. When perennials are in full bloom, who notices the foliage? But, for the 80 percent of the time that we see the plants not in bloom, all we can see is foliage.

Try placing large, thick-foliage plants like hosta just behind the finer smaller foliage of Astilbe or juniper. Or try a tall spiky fern fronted by the dark green, glossy foliage of a wild ginger. It's fun to experiment with different combinations to incorporate all three design elements. You'll be a better gardener for it.