Sometimes, the most memorable plant combinations consist of varieties that you would not imagine could have such an impact. Individually, they might not be too interesting, but brought together in a garden bed, they leave an indelible impression.

I saw an example of this the other day. The bed consisted of a variegated euonymus with foliage that was mostly gold, ordinary zonal or fish geraniums with flowers in fire engine red, and bluish-purple flowered sea lavender (Limonium perezii). Gold and red and purple make an unmistakably vibrant display, but they would not come off half as brilliant without the accompanying sea green of the geranium foliage and the ample dark green leaves of the sea lavender, which can extend up to 18 inches.

Years ago, my first encounter with sea lavender was along cliffs overlooking the ocean at Del Mar, near San Diego. At the time, I thought it must be native to California’s coast, since it had such a rough and ready look and was obviously not being cared for by any living soul. Only later would I learn that the Canary Islands, located off the coast of northwestern Africa, are the exclusive habitat of sea lavender. What we see along our shores are naturalized colonies of this plant, originally imported from across the seas, which self-sows with abandon — its seeds having jumped the fence of local gardens — where soil is sandy and moist ocean air hovers all around. Such is the unique bluish-purple of sea lavender that it has become a common practice to interplant it with constantly flowering white floribunda or shrub roses such as iceberg or White Meidiland.

Variegated euonymus varieties with green and gold evergreen foliage show themselves as golden throughout the year. This plant solves the problem of annual flowers that are good for a season or two but need to be regularly replaced. The abiding presence of euonymus means its golden splendor never dulls. The only other shrubby plant with variegated gold and green foliage — that appears essentially gold — is Gold Mound Duranta. The advantage it holds is due to euonymus’ tendency to develop powdery mildew, while Duranta is generally disease free. Two gold and green variegated vines also come to mind, although their gold is not as bold. One is variegated potato vine (Solanum jasminoides variety Aurea) and the other is variegated bower vine (Pandorea jasminoides variety Variegate), with the latter featuring pinkish-white trumpet flowers with large crimson centers.

Of course, the most solid yellow of all — that would contrast most sharply and outlandishly with red and purple — is euryops daisy. When it comes to reliability and flower display, what the fish geranium is to red, the euryops daisy is to yellow. Euryops daisy may be caught blooming at any time, although it flowers most in spring and fall. It might be said that there is no truer, deeper yellow than that of Euryops daisy petals. To enhance the visual power of this plant, utilize the cultivar with green leaves (Euryops pectinatus variety Viridis) as opposed to the more commonly seen gray-leafed type. Viridis has verdant, dark green leaves that give it a springtime look throughout the year.

The red, gold, and purple in this bed would make a distinctive statement on their own, but the crowning jewel of this arrangement is so-called annual vinca, whose flowers are pink. I say “so-called annual vinca” since this species (Catharanthus roseus) can persist for up to two decades. To understand how you can grow such long-lived annual vinca, let me introduce you to my neighbor, Robert, who is 93 years old. He seldom waters his flower beds, which at the moment are bone-dry, yet he has annual vinca plants that are more than 10 years old. For the uninitiated, perennial vinca customarily refers to two ground covers with mauve-periwinkle flowers. Both grow best in filtered sun, whether we are talking about the larger-flowered Vinca major or the tighter-growing, and probably more shade-needy, Vinca minor. In any case, annual vinca got its name from the fact that it is watered too much, so it barely lasts for more than a month or two in the garden. Yet my friend hardly waters his flower beds, and he has stout, 2-foot-tall by 2-foot-wide annual vinca mini-shrubs, over a decade old, to show for his efforts or, perhaps I should say, to show for his benign neglect.

Shifting gears, I must say a few words about the sweet pea shrub (Polygala x dalmaisiana), since it seems to be everywhere this spring, and throughout the year it is nearly always in bloom. Sweet pea bush is a rangy plant that can grow 6 feet or taller and has a flower color that combines pink, magenta and a dash of purple. It is virtually always producing flowers. Cut it back to keep its form more compact, but planted on your property line, it provides separation from your neighbor’s yard. Sweet pea bush does best growing in full sun, but it can handle a bit of shade. There is a dwarf version (Polygala fruticosa variety Petite Butterfly) that only grows 3 feet tall and keeps to a more compact form.

Do you have a memorable plant combination that more of us should know about? If so, please send it to Joshua@perfectplants.com. Your gardening conundrums and successes, as well as questions and comments, are always welcome.