Growin' of the Green

St. Patrick's Day is all about the "wearin' of the green," but did you ever consider the "growin' of the green" in your landscape? In high school biology, we learned that plants use the green pigment chlorophyll to photosynthesize, removing carbon dioxide from the atmosphere and releasing oxygen in the process. Chlorophyll appears green because it absorbs blue and red light. What you may not realize is that chlorophyll is several pigments; the primary ones are chlorophyll a and chlorophyll b. Both absorb different wavelengths of blue and red light and appear in our plants as light and dark green, respectively. Other pigments that affect vegetation color, in addition to chlorophylls, include reds and blues (anthocyanins), yellows (flavonoids), and oranges (carotenoids).

So how does this return us to St. Patrick's Day and the "growing' of the green?" These pigments all combine in various plant species—cultivars and natives—to provide us with a myriad of green shades for our gardens and landscapes. Research has shown that green, found in the middle of the color spectrum, is easy for humans to see and can be restful and calming to view.

Color is a hue, which is the true color produced by the plants' chlorophyll pigments. Tint (lighter hue), shade (darker hue), and tone (less bright color) further enrich the depth of green in foliage. When we look at cultivated and natural landscapes, they are generally dominated by green-colored foliage: trees, shrubs, perennials, annuals, and turf. We can play upon the tints, shades, and tones of green foliage when designing gardens and landscapes. Bloom, regardless of plant type, offers us a rainbow of colors to enjoy. However, the enjoyment is not long-lasting, as flowers wilt and fade quickly; the green of foliage lasts much longer. Showcasing green foliage with an array of leaf sizes, shapes, textures, and variegation, combined with colorful blooming plants, increases the richness of any garden or landscape. Here are a few plant ideas for incorporating tints, shades, and tones of green in your gardening and landscaping plans.

Dark shades of green are found in conifers and evergreen shrubs, but even these offer a variety of shades for consideration. Classic English yews (Taxus baccata) are popular evergreen landscape plants found in many sizes and shapes, from tall columnar to low creeping varieties. There are also many shades of green available in cultivars such as 'Repandens Aurea' (green with yellow to cream edges) and 'Standshii', with yellow to yellow-green undersides. American holly (Ilex opaca) boasts dark green spine-tipped leaves. Look for the cultivar 'Greenleaf' for deep, dark green, dense foliage. In contrast, the hybrid blue holly (Ilex x meserveae)has foliage with a distinctive blue-green shade, especially cultivars like 'Blue Princess' and 'Blue Prince'. Rhododendrons (Rhododendron spp.) are found with a variety of hues that change with the seasons. For example, Rhododendron x 'Elite' (P.J.M. hybrid) is a cultivar whose green foliage turns into a purple-reddish hue in the fall and winter. Use these shrubs as focal points to complement your year-round foliage and blooming perennials.

Native trees and shrubs such as redbud (Cercis canadensis) and ninebark (Physocarpus opulifolius) have cultivars that offer varying hues of green. The new foliage of redbud 'Vanilla Twist' has a lime green/chartreuse tint. Ninebark 'Dart's Gold' foliage, also chartreuse/lime green in color, changing to a golden hue in the fall. A hedge of ninebark shrubs with varying tints and shades makes a stunning year-round display, while providing food and shelter for birds and wildlife.

Among perennials, hostas (Hosta spp.) are a favorite ground cover that appear in many shades of green from bright yellow-green to a green that is subtly blue-gray. Some hostas have wrinkled or toothed leaves to also add texture, and others may be striped in whites or other shades of green for a little additional color. The cultivar 'Guacamole' has glossy oval leaves with a chartreuse-tinted center; the flowers are aromatic. The native ground cover wild ginger (Asarum canadense) has beautiful, dark green, heart-shaped leaves that form a solid ground cover. Also consider ferns as a ground cover offering many shades, tints, and tones of green and assorted textures. Ostrich fern (Matteuccia struthiopteris) is deer-tolerant, and Japanese painted fern (Athyrium niponicum) provides frosty green, white, and red colors as a ground cover. All of these plants work very well in shady, damp areas.

Continue the "growin' of the green" throughout the seasons for interest, diversity, and beauty in your home landscape. To learn more about adding green to your gardens and landscapes, and other principles of garden design, visit the Penn State Extension articles Principles of Garden Design and Choosing Shrubs for Your Garden.