Green carnations for St. Patrick's Day are a great project for kids: put a few drops of green food coloring in a glass of water, add a white florist's carnation (cut off an inch of stem for better absorption) — in an hour the flower starts to color; overnight it's transformed.

But I'm thinking of flowers that naturally bloom green. The unexpected color catches the eye and piques the curiosity, adding mystery to the garden, and a new dimension to arrangements. Still, the way each variety shows green can be tricky.

Several Hellebores have green flowers, but the ones hardy here in zone 5 have other colors in the flower too. For example H. orientalis, Lenten Rose, which is a greenish cream, and H. purpurascens: purplish or slate-gray (often pink- or purple-flushed), with light green interiors. Since the flowers hang down, I think the only way to really get a good look at those interiors, is to float the blooms in a bowl of water.

Viridiflora tulips have green blazes on the exterior of the petals, which are mainly another color. (In 'Greenland,' they're pink; in 'Spring Green,' white.)

Some flowers display green for only part of their life. The miniature rose 'Green Ice' starts white, then turns soft green. Kniphofia 'Green Jade' starts green, then becomes cream and white.

Eryngium Giganteum, that sea holly also called "Miss Willmott's ghost," starts out with its thistle-like flowers pale green; then they turn steel-blue. The "ghost" part is the big showy bracts that surround the actual flower: they're silvery gray. E. yuccifolium (aka rattlesnake-master) has greenish-white flowers.

Yellow-greens seem to be more common, like the frothy flowers of Lady's Mantle, (which also has fascinating leaves: pleated; and hairy, so that water beads up on them.) Or Angelica archangelica: six-foot stems topped with lacy, umbrella-spoked pompoms.

Unusual plant parts often give green flowers their color. In many euphorbias, it's bracts — modified leaves. (In 'Emerald Jade', the tiny flowers also are bright green.) In the flower called "bells of Ireland," the green cup is composed of modified sepals (outer flower parts, that cover petals before buds open). Rudbeckia 'Green Wizard' has prominent green sepals around a big black center.

For 'Envy' zinnia, the trick is a little shade (usually, zinnias need maximum sun). Though I moslty avoid annuals, I love this quirky beauty. Plus it's fun to watch visitors' amazement.