Mysterious Plant Changes

Gardening is full of surprises. One of the most puzzling is when flowers unexpectedly change color or form.

I hear from many gardeners who wonder why this happens—a purple patch of flowers that becomes yellow; an oddball red bloom on a white-flowering plant; or flowers that take on the characteristics of the surrounding plants (like the striped tulips to the right).

Although it may seem like the work of mischievous garden gnomes, there typically are three possible reasons for such plant changes: mutations (also called "sports"), hybridizing, or offspring plants that exhibit different features than the parents. To determine what caused these changes in your yard, start by examining the plant's history.

A Sporting Chance

For instance, reader Dawn Scheppke of Eau Claire, Wisconsin reported that when she planted purple irises in her flower bed of yellow ones, several irises emerged as purple and yellow the following spring.

Since the two irises didn't have time to cross-pollinate (that would take longer than a single season), some of the irises probably sported, a spontaneous mutation from the parent plant...though the timing is oddly coincidental.

When flower growers discover a sport, they often propagate them and sell the new plants for their unique size, color or flavor. The golden delicious apple is a tasty example of a plant that first emerged as a sport. Many variegated plants also are the result of sports. But sometimes, these plants revert back to the parent plants' original color and form.

That's what happened in Phyllis Felton's garden in Castle Creek, New York. She wrote to ask about her variegated hostas that are turning solid green. Unfortunately, there's nothing a gardener can do to stop this process. Just enjoy the new surprises each season.

Hybrids Happen

Plant changes also occur through hybridizing—when two plants cross-pollinate. This results in a reshuffling of genetic material, with the offspring taking on various characteristics from both parent plants. Jane Elliott of Manchester, New Jersey experienced a somewhat different dilemma. A division of her blue balloon flowers turned white after she transplanted them.

While this may be a sport, it could also be the result of the offspring not growing true from seed—a common problem with hybrid plants, which typically don't produce seeds that carry the genetic material needed to grow an exact copy of the parent plant.

It's possible the transplanted portion died, but then dormant seeds in the soil sprouted and grew. These seedlings didn't come true from seed, causing the resulting flower color to be white instead of blue.

Other Explanations

Donna Schubert of Republic, Ohio knows that grafted roses—including most hybrid teas—also can change color. For 7 years, her rosebush boasted orange blossoms. Then one year, red roses appeared on the same plant (right).

This happened because propagators graft a single bud of the desirable rose, orange in this case, onto a hardy root system. If part of the grafted portion dies, often as the result of cold winter temperatures, the hardy rootstock will take over.

Believe it or not, diseases can also cause changes in plant characteristics. Europe's 17th-century tulip craze, known as Tulipmania, was the result of a virus. The disease infected a plant, causing a yellow streak to develop in a red flower. The virus didn't hurt the tulip, but the resulting bloom caused people to go gaga trying to obtain the unique bulbs.

The bottom line when it comes to plant changes? Remove the new plants if you don't like them or if they compete with your desirable plants. Or leave them be.

You just might end up with a sport or a hybrid that's better than the plant you purchased.