Why Are Leaves Purple?

Ilona Erwin

And Other Leaf Mysteries

Anthocyanins are naturally occurring pigments and they are the cause of purple pigments in plants. There are said to be over 500 anthocyanins. Anthocyanin production requires light, and sunny exposures will increase intensity of color; acidity affects it as well. Some of the most exciting perennials, trees, and shrubs contribute varieties with these color variations.

Whether through breeding or by mutations, purple-foliaged plants fascinate and draw attention to themselves. Gardeners often love them for both novelty and contrast. Adding burgundy and deep red flowers creates a rich tapestry, always dramatic and bold in their effect.

Despite red’s attribute of being visually dominant, once colors deepen they tend to recede from the field. Many dark red and purple flowers have contrasting accents of yellow and gold, and the color combo can be borrowed to heighten the effects of purples and burgundies in plant foliage. But bear in mind that too much can drain some of the mystery from a color arrangement that could be better suited to coupling with silvery leaves.

Silver gray foliage is a subtle partner to the purples. It has more harmony of hue while playing off the contrast of light and dark between them. Silver foliaged plants often have a soft texture which adds to the drama, a perfect backdrop for the muted effects of pastels or bright displays of hot orange.

purple sand cherry

purple sand cherry

What are some popular examples of purple, mahogany, and burgundy leaves in the garden?
In shrubs and trees, the varicolored types of European Beech, Fagus sylvatica are some of the best. Purple Sand Cherry,Prunus X Cistena, is commonly available, and one I have grown. It lasted about 20 years in good health, here. After a very bad winter I lost it, but they are not long lived under any circumstances. Norway Maple, Acer platanoides ‘Crimson King’ , is another common one, but one I dislike. It always looks heavy and leaden, is difficult to meld into the landscape, and Norway maples have such greedy roots that it is hard to grow things in their company. but it is popular and widely available.

Prunus Cerasifera ‘Atropurpurea’, or the purple leaf plum, is another small tree with a short life and only hardy to zone 5b. As long as the gardener is prepared to lose the less hardy,shorter lived trees and shrubs, they can be attractive second players in a garden. Purple Smoke tree, Cotinus coggygria, is a longer lived and hardier choice. A number of Japanese maples have burgundy to purple colors, and I have just started growing those. They are planted in protected spots. One tree I don’t have that I would like is Corylus maxima ‘Purpurea’; although now that Japanese beetles have proved voracious consumers of my ‘Harry Lauder’ corylus I may not risk planting it.

Rose Glow courtesy Great Plant Picks

courtesy Great Plant Picks

Here are my picks:

The Story of My Purple Sand Cherry


Perennials Offer an Innumerable Array

Since this is a favorite way plant breeders have of playing with plants, there are always purple leaved cultivars coming into the market. Just a list of the new Heucheras give you as idea of how exciting some of the choices are. These also are reaching into the copper and chartreuse tones, which make great companion colors for the purple leaf shades. So the heucheras rate high on my (and everyone elses) list.

foliage colors

Foliage colors, Euphorbia, Ninebark, and Sedum

Cimcifuga racemosa, bugsbane, has some purple varieties. It is a fine, tall plant with white, wispy, wands of bloom. Penstemon digitalis ‘Husker Red’ is one I’ve grown- it survives in some of the worst places and its whitish flowers are similar in color to the bugsbane. Salvia lyrata has several varieties of purple leaf cultivars. It has been hardy for me so far. Native east of the Mississippi, it looks like Ajuga, another choice with a range of purple to mahogany colored leaves. Both those plants hug the ground. Sedum X ‘Mohrchen’ is a mid size plant, ‘Vera Jameson’ being the variety more commonly offered. I love a plant that holds several strong colors in one package: Euphorbia polychroma ‘Bonfire’ is exactly that, and it is included in my driveway planting, strongly based on purple foliaged plants.

My list of picks: All those named above included-

  • Ajuga reptans
  • Eupatorium ‘Chocolate’, Joe-Pye Weed
  • Euphorbia polychroma ‘Bonfire’
  • Heuchera ‘Cappuccino’
  • Salvia lyrata
  • Sedum X ‘Mohrchen’
  • Sedum ‘Purple Emperor’

The Annual Parade

If the perennial choices seemed endless… once you open the field to those plants which are grown only seasonally, not hardy in your area- well, I can’t very well write a book! But I can list some that I really enjoyed growing in my containers. Annuals grown mainly for their foliage look best in containers rather than in the ground, I think. Sometimes their colors are too gaudy for a Northern clime- but welcome as eccentric and exotic visitors in containers which we want to look bright and splashy.

I have to put in a word for the Coleus (now properly called Solenostemon) selections available. They have outstripped even the heuchera in the breeding fervor to produce scintillating foliage colors, many of them of such deep mahogany to almost appear black, often with the neat scalloping of a contrasting color. I have a new love affair with them this year. They also make great houseplants and are easy to start from a cutting in a vase of water.

My list of picks:

  • Sweet Potato vine, Ipomea batatas
  • Purple Fountain Grass
  • Carex tenuiculmis ‘Cappuccino’, sedge grass
  • Persian Shield, Stobilianthes dyeranus
  • Oxalis purpurea
  • Canna indica purpurea
  • Coleus- too many to name
  • Dahlia- ‘Roxy’, ‘Bishops Children’, ‘Redskin Mixed’, ‘Diablo Mixed’
Annual bed of foliage plants

Annual bed of foliage plants

Purple Leaf Plants I’d Like To Try

  • Geranium maculatum ‘Espresso’
  • Corylus maxima ‘Purpurea’
  • Purple Haze Dahlia
  • Dianthus barbatus Sooty

The Most Important Thing

The most important thing I’d like to say about using purple, mahogany, and burgundy leaved plants in your landscape design is that it can appear garish when using too many contrasts, and depressingly heavy when forgetting to brighten up all those deep leaf colors. Follow nature’s cue and provide wispy, light, accents and companions. Use the plants with an aim for subtlety in situation and in combination. Otherwise, treat your dark leaf plantings as a focal point: with confident intent and as a main feature (limited in number). Other than that, have fun- because the feeling that comes from playing with foliage effects is fun, exciting, and can produce some of the most satisfactory of your design efforts.

Not so important , but worth considering….
I haven’t included the names of specific cultivars within some plant choices, since many different offerings are on the market, but take a clue to look for the dark foliaged varieties in the plant named.

You probably realize that this is just a small sample of the plants available with this deep foliage color form. Keep your eyes open in the catalogs and plant nurseries for those you wish to incorporate into your garden plans. If you put them together with the important caveat mentioned, you will have spiced up your yard and set it apart from the usual. Remember that containers are an easy way to experiment with new ideas- their color lessons can be transposed to the larger beds and plantings of your yard.

Purchase a purple leaf plant:
Purple Leaf Sand Cherry
Purple Petticoats Coral bells
Ninebark ‘Coppertina’
Suggested Reading:


Chemistry of Autumn Leaf Color from About.com

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Ilona Erwin, author

Meet the Author

Ilona Erwin

I started working on this website beginning in 1998, when it was part of Ilona's Reflecting Pool. Since then I've branched out into a number of online endeavors and work at writing lots of content for my sites. "Ilona's Garden" remains my primary site and is dedicated to home gardener's success.