Do you love trying new plants to add a little extra “zing” to your garden? If so, you’ve probably bought or lusted after a plant or two with variegated leaves or flowers. Variegation means that leaves have white, yellow, or other colors in addition to green, or flowers that have multiple colors rather than solid color petals. The variations may be regular bands, edges, patterns, or wild splotches. Although you can find annuals, houseplants, perennials, shrubs, trees, and even herb and vegetable plants with variegation, they are the exception, not the rule. Growing these unusual plants comes with both risks and benefits!
What causes variegation?
Variegation occurs for many reasons.
• It comes naturally. Where variegation has evolved over generations of plants, the plants’ seeds produce new plants with the same characteristics. This pattern variegation may occur in flowers or leaves.
• It spontaneously occurs as a “sport” or chimera. Plant can spontaneously produce sections that have cells with two distinct genetic characteristics through mutations. You may spot a branch on a plant you are growing that looks different from the rest of a plant: while most leaves are solid green, one section has white patterns. In this case, if growers want to propagate new plants with this variegation, they must do so vegetatively—from a portion of the parent plant—rather than from seed. The houseplant golden pothos (Epipremnum pinnatum) is easily propagated from cuttings. ‘Night Sky’ petunias are propagated through tissue culture to produce plants that have purple flowers with white splotches—but these patterns vary with temperature (see “For more info below”).
• It is a symptom of a viral disease. Many variegated plants produce their color variations because of viruses. The most famous example is early generations of tulips that displayed color breaks when infected with tulip breaking virus—as you might expect these tulips eventually declined and contemporary tulips with these distinctive markings are genetic variations, rather than diseased bulbs. Similarly, many variegated Hosta varieties were found to be the result of Hosta virus X and their introduction led to an HVX epidemic and subsequent virus testing of new varieties to try to contain its spread. However, some Camellia varieties with multicolored flowers are plants bred with Camellia yellow mottle virus, and some brightly colored Canna varieties are selections of plants with Canna yellow mottle virus.
Pros of variegation
The primary advantage of variegation to gardeners is the plant’s distinctive appearance. These plants can serve as important focal points in your landscape design.
From the plants’ perspective, variegation may protect plants from herbivores in a variety of ways (Lev-Yadun, 2015). Other researchers are investigating if white patches on variegated plants might facilitate photosynthesis (the process plants use to process sunlight into glucose) when temperatures are low, helping them survive lower temperatures than solid green plants.
Cons of variegation
Some people just don’t like variegated plants and gardeners certainly risk having garish landscapes if they overuse them! Linda Chalker-Scott, Extension Urban Horticulturist, describes variegated plants as “tarted-up” and notes they often looking “environmentally stressed and/or diseased.”
• Weaker growth/Failure to thrive. In fact, some variegated plants don’t do as well as their unvariegated counterparts. Because variegated leaf sections don’t have the chlorophyll of green sections, photosynthesis is typically less efficient, and many variegated plants show weaker growth. Similarly, variegated plants that carry viruses may decline because of the viral infection or even pass the disease on to related plants in your landscape.
• Reversion. Another problem is variegated plants that are “sports” or chimeras may revert to solid green—if you see such new growth, remove it immediately!
• Propagation issues. Unless you know the source of variegation in your plants, you may have difficulty producing more plants—especially from seed. Also, many variegated plants are patented and cannot be propagated for resale without permission.
Article by Buncombe County Extension Master Gardener Volunteers
For more information:
Lev-Yadun, Simcha (2015). The Proposed Anti-Herbivory Roles of White Leaf Variegation. In U. Lu ̈ttge, W. Beyschlag (eds.), Progress in Botany, Springer International.https://www.researchgate.net/profile/Simcha_Lev-Yadun/publication/300009810_The_Proposed_Anti-herbivory_Roles_of_White_Leaf_Variegation/links/592b28ad0f7e9b9979a95996/The-Proposed-Anti-herbivory-Roles-of-White-Leaf-Variegation.pdf
Viruses and ornamental plants:https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-11-11-0928-FE
Night sky petunias:https://www.zmescience.com/science/night-sky-petunias-03042019/
Why plants lose their variegation:http://gardenprofessors.com/why-doesnt-my-plant-look-like-it-did-last-year/