...of Mutants, Cold Springs, Genetic Predisposition and Roses
by Lorraine Syratt ©2009 -2011
Some garden roses are prone to proliferation which turns a beautiful flower ugly in its center. Rose proliferation isn't a killer and it can avoided.
The reason for rose proliferation is not fully understood. The effect is usually noticed when a rose bud tries to form within a bloom that has already opened. Often, a stem with unfurling leaves could grow out through the flower with the bud at the end of it. It's a freakish event for the rose lover.
Proliferation in roses has been known for centuries. Botanists of the 18th century called these new buds "childings," due to the symbolism of the mutation.
Some rosarians believe rose proliferaton is a viral disease that occurs in only certain varieties of roses, but it has been known to happen in all rose types. Old or antique roses are particularly susceptible to the disease.
Rose Genetic Mutation
Rosarians also believe it could be a genetic error or mutation in the reproductive parts of the rose. Not all the flowers on the single rose plant infected may be suffering from proliferation. It could only affect a few or as many as 50% of the flowers.
Spontaneous Rose Proliferation
Rose proliferation can be random. It can happen one year and not the next. This is thought to be a spontaneous genetic mutation as the blooms develop. Rose gardeners argue that it could be due to weather patterns. Hence the randomness. Late frosts in spring after the rose is beginning to unfurl it's leaves and buds can result in proliferation.
In roses that only bloom once in spring, this can be very disappointing to the gardener. But for roses with repeat-flowering habits, the second-flush of flowers is often free of proliferation.
Rose Choices to Avoid Proliferation
While the reason for rose proliferation is still not known for certain, it is known that cold springs and too much nitrogen in the soil can cause problems with both the number of flowers as well as the health of the flower.
Proliferation is a known effect from sudden cold temperatures. Gardeners in colder gardening zones who have proliferation in their roses, should consider planting only the hardiest roses. As more roses are added to the garden, repeat-flowering roses should be considered, including shrub roses and Explorer roses. Avoid any rose that has the word "prolifera" in its name or heritage.
While old or antique roses are known to be hardy, some varieties, especially the gallicas are prone to proliferation. These roses are thought to be predisposed genetically.
Saving the First Rose Blooms
Proliferation isn't harmful to the rose. It's not being attacked by fungus or insects and it won't die from it. But with roses that only flower once in spring with no repeats, it can be very disheartening. A careful watch can ensure a satisfactory result.
When signs of proliferation appear on the bush, it is best to remove the affected flowers immediately. While the mutations will not destroy the plant, they will divert energy from the remaining healthy flower buds. The spring rose flush could be saved.
Note the roses in the garden that appear to be genetically predisposed to proliferation and give them a later spring pruning, just before the leaves and buds unfurl.
The photos in this article are of the sorry old roses in my own garden. I failed to follow my suggestions. Next year ....