July 26, 2014

1 - You can grow roses from seeds that form on your hybrid roses if you follow the rules, but the results may be surprising.

Yard and Garden July 26, 2014


I am usually very particular about deadheading my hybrid roses to encourage additional flowering. However, this year I was away from home and the rose hips have formed. I was wondering how difficult it is to grow roses from seeds. Will you tell me how to do this?

-Alice S.


Roses are not difficult to grow from seed if you follow the proper procedures and are patient. You must first let the rose hips mature so that the seed inside also mature. The rose hips will turn red, orange, yellow, or even black in one species when they are mature. Yours will probably turn red or orange. Once the seed have matured, you can remove them from the rose hip and begin the process of overcoming dormancy.

Rose seed as well as the seeds of other temperate climate shrubs and trees are dormant when mature to keep them from germinating in the fall. They must experience winter cold before they will germinate. In nature this occurs in the soil, but you can increase your chances of getting seeds to germinate by treating the seeds in your refrigerator.

The process of overcoming the natural dormancy of rose seeds is to keep them moist and cool. Horticulturists call this treatment "stratification". Long ago gardeners just created layers (strata) of seeds and compost in pots left outdoors in the garden over the winter. New Mexico may not provide adequate, consistent low temperatures, so you can place them on a moistened sheet of paper towel in a resealable plastic bag in the refrigerator. The ideal temperature is about 39 degrees, but any temperature between freezing and 45 degrees will do the job. Temperatures below freezing stop the metabolism that produces the gibberellin and temperatures above 50 degrees cause the breakdown of gibberellin. Temperatures near 39 degrees created the most rapid preparation of the seeds. During the period of refrigeration, metabolism in the seed produces a plant hormone, gibberellin. This is like a biochemical calendar because once the hormone has reached an appropriate level; the seed will germinate when warm temperatures are provided. Without adequate accumulation of gibberellin the seed remains dormant. This will be your sign that the seeds are ready to be planted in pots. The critical time duration for this treatment is 6 to 8 weeks at a constant 39 degrees. It takes longer at low temperatures above or below 39 degrees. Some of the seeds may begin germinating in the refrigerator once sufficient gibberellin has accumulated. At this time you can take the seeds from the refrigerator and plant them in pots of potting soil in a sunny window. The young plants will need to be kept indoors until there is no chance of frost in the garden. Once the weather has warmed you can plant your roses in the garden.

The real fun may take a few years to see the flower develop. Because the roses are hybrids with genes from a variety of sources, and because each seed has inherited different genes, the plants may all be different. Seed from a yellow rose may produce a plant with red or white flowers. Some may be single with only 5 petals; others may be double with many petals. Some may be fragrant, some may have no scent. The chance of finding a rose that is superior to the parent rose is slim, but not impossible. It is worth the attention and time to grow roses from seeds just to see how the genetic lottery works. If you find that you have grown a true blue rose, will you share your millions with me when you sell the plant to a large nursery corporation?

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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