RHA Newsletter 2(6): 2-4 (Aug 1970)
Breeding Roses Indoors
Dolgeville, New York, 13329
It is so much fun to grow and breed roses indoors under lights I cannot see why everybody doesn't do it.
Seriously we are well along on a project to breed better miniature, pot. dwarf and shrub roses and greet the new year with over one thousand rose seedlings coming into bud and bloom under fluorescent lights. They are blossoming at six weeks of age or less from seed germination. This is unheard of by older methods and illustrates the possibilities with fluorescent light indoor growing.
These seedlings are growing upstairs in our house because we need all the space available in our greenhouse for growing African Violets and other gesneriads.
The rose seed is from hips grown mostly on fertile diploid (14 chromosomes) miniature and dwarf roses which we do not find room for in the greenhouse. These mother plants are pollinated each day through out the year as they blossom and have flowers and green and ripe hips most of the time. We use mostly mixed pollen from two main lines of breeding. One derived from the old diploid tea, poliantha and miniature roses, the other from descendants of Therese Bugnet (R. acicularis X R. rugosa kamtchatica) X (R. amblyotis X R. rugosa plena) X Betty Bland. Added to this conglomeration are descendents of yellow and copper colored tetraploid (28 chromosomes) hybrid teas and floribundas.
The variation in these seedlings is amazing. Some have old fashioned looking blossoms and the strong clove scent of their rugosa ancestors, others have long pointed buds and tea scented flowers. The colors vary from white through pink, red, yellow and copper and the latter two are often fruit scented. The size of the plants and flowers vary greatly also. Some of the plants are thornless, other have fine prickles, hooks and combinations of the two. Most have less thorns than other roses.
Everything possible is done to speed up seed germination, growth evaluation of the seedlings and further breeding to get the combination of black-spot resistance, resistance to mildew and the winter hardiness we want. By winter hardiness we mean plants that need no winter protection and do not freeze back to the ground under our conditions when the temperatures go to 20 and 300 below zero every winter.
Mixed pollen is used and has many advantages. As soon as promising seedlings blossom, we pollinate them to test them for fertility. Mixed pollen supplies males, some of which are more compatible than others to certain females. It cuts down time and work and gives us some combinations that we wouldn't otherwise get. In the greenhouse the flower of the mother plants are not emasculated or covered. Records of the mother plants are kept and we can often tell the male by the appearance of the seedling. The important thing to do is to achieve the plant that is wanted. Its genetic make up could be determined by test crosses later if need be.
Seed is removed from the hips when fully ripe. It is cleaned and coated with root-tone, mostly because of the fungicide content and planted immediately. As many as 500 seeds in a glass refrigerator dish 4" x 8" x 3" deep (outside diameter). We do not float the seed in water because some of it is small and much viable seeds would stay on top.
We use vermiculite and wet it thoroughly with 1/2 tsp. of 20-20-20 Hyponex fertilizer to one gallon of water the same as we do for violets and other seed except the rose seed is covered about 1/4 inch deep. We like to put a layer of 1/2" to 3/4" of propolite (perlite or charcoal would do) in the dish first and then the layer of about 3/4" of vermiculite on top of this. This gives better aeration. After the seed is planted the glass cover is put on and the seed is kept warm at 75_800 for two months. Considerable seed will germinate during this time. As fast as the plants come up they are removed and potted. Three inch Jiffy pots are simply filled with horticultural grade vermiculite and wet thoroughly with the 1/4 tsp. of fertilizer to one gallon of water. A hole is made with a plant label and the tiny seedling sealed in with a spoon of sterilized fine sand and watered again. At the end of two months the seed dish is placed in a refrigerator at about 41° for further germination.
An example of good fluorescent light set-up is a bench 5' X 6' inside diameter with sides about two inches high. This is lined with 4 mil plastic and filled with horticultural vermiculite 1 1/2" deep. Three light fixtures containing two 40 watt warm white tubes each may be hung above this bench and a time clock used to give about 16 hours of light. The lights may be hung about 12 inches from the tubes to the vermiculite and can be raised for higher plants. One could also experiment with some of the grow lights. The vermiculite in the bench is first wetted thoroughly with plain water then the plants are watered every day enough so that the surplus will keep the vermiculite beneath them wet. Make a hole with your finger to see that the bench is not flooded.
We have hot and cold water piped to a faucet and a merit commander proportioner that injects the above mentioned amount of 20-20-20 fertilizer in the water. The water pressure is regulated by pressure reducing valves so we can stop the flow of water through the hose easily when moving from bench to bench.
Any plants that are saved for further evaluation are potted in the same soil mix we use for gesneriads and fed at each watering.
If we want a few plants from a certain seedling, cuttings are taken and rooted in a pyrex casserole dish with a cover. The dishes are prepared and watered with the dilute nutrient solution the same as with seed. Cuttings will root in 10 to 14 days and are potted in peat pots of vermiculite or could be potted in sterilized soil. After potting they must be watered and covered with plastic or something to keep the humidity high for a few days or the leaves will wilt and you will loose them. Cuttings can of course be rooted in full sun under mist or sprinklers.
We get excellent growth at temperatures around 80° with out much drop at night. Mildew must be controlled although we eventually hope to breed plants resistant to it. Red spider absolutely cannot be tollerated under a fluorescent light set-up. Plants will of course remain free of spider until it is brought to them. To rid a plant of spider it is best to cut most of the plant away and even remove all remaining leaves and spray several times while the plant is regrowing.
A free blooming fertile group of diploid roses ranging in size from tiny miniatures to big shrub size is rapidly being developed. All blossom at about six weeks of age when only a few inches high or are thrown out. The tinniest ones only grow from 3 to 6 inches high while the largest quickly reach the lights and have to be kept cut back if we wish to keep them to put outdoors in the spring.
All promising seedlings are pollinated with mixed pollen as soon as they blossom in search for better seed producing plants in the miniature and dwarf sizes. Wanted are descendents of Therese Bugnet and plants of the different colors, yellow, salmon and copper especially. We do not have any selection of these roses for sale. Seed of Fairy rose and Nana multiflora can be purchased from George W. Park seed Co. Inc., Greenwood, South Carolina 29646. These roses will also blossom in six weeks from the time the seed germinates if grown under the above conditions. Take a lesson from nature, plant plenty of seed and discard the plants that do not take your fancy. Do not expect hybrid tea buds and flowers. They have a distinct character of their own. The plants grow taller than some of the smaller miniatures. They blossom freely and are more free of disease and are more winter hardy than floribundas.