RHA Newsletter 2(9): 8-9 (Fall 1971)
OBSERVATIONS ON ROSE SEED GERMINATION
By Paul E. Jerabek

The following conclusions are based on hundreds of experiments over a four year period:

  1. Although green hips may produce some viable seed, proper ripening is necessary for good germination.
  2. Seeds of hardy varieties-tend to ripen quicker than those of tender varieties. Some varieties may never color up, especially some yellow hybrid teas.
  3. Green hips threatened by a severe freeze can be cut with some foliage on 6"-12" stems and ripened in damp perlite under artificial lights. By this means the hybridizing season can be extended about a month.
  4. In general, "floaters" will not germinate, but this is not true of small seeds of such varieties as The Fairy and the hybrid rugosas.
  5. Of a given variety, large seeds germinate better than small ones; and seeds sticking well out of the pod so that they are easily rubbed off, germinate poorly.
  6. Outdoor germination has consistently given me better results than any indoor system I have been able to devise, so far. Seeds planted outdoors were always protected from extreme. cold by some insulation.
  7. Indoor germination is improved by an after-ripening treatment of the seeds in a plastic bag at 35°F. Such treatment in the pod is not effective,
  8. Optimum after-ripening duration is dependent on the cold-hardiness of the variety. Hybrid teas require about 30 days, floribundas about 60 days, and hardy climbers and shrubs about 90 days.
  9. Moisture content during after-ripening is very important. Optimum moisture content can be obtained by lightly "blotting" off excess moisture with a paper towel after the floatation test. Air drying for 3 hours drops germination to near zero, and adding 50 drops of water to 100 seeds does likewise.
  10. Proper after-ripening shortens the time from planting to germination.
  11. Dropping the temperature to 16°F. or lower during after-ripening drops the germination drastically. This is true whether the seed is in the hip at the time or in a plastic bag.
  12. Germination of open-pollinated seeds varies tremendously, depending on the variety. In a test of 15 varieties with 90-day after-ripening, germination varied from 66.7% for "The Fairy", to 0.5% for "Sunday Best". With a 60-day treatment "Chuckles gave a 79.5 germination.
  13. X-Ray treatment of seed (normal dental photographic exposure) drastically reduces germination and induces large percentage of deformed seedlings.

The following observations cannot be considered absolutely conclusive because of the limited scope of my experiments:

  1. Floating in "Chlorox" solution showed no advantage over floating in water.
  2. Presence of. small amounts of "Spergon", "Rootone" or "Rapid Grow" during after-ripening showed no advantage.
  3. Spraying with. "Gibrell" (potassium gibberelate) drastically reduced germination.
  4. After-ripening in an air-tight bottle appeared to drastically lower germination..

Although experimentation has enabled me to improve my germination by about 300%, there is still room for improvement and I realize that my conclusions may not be valid under different test conditions. Your comments and suggestions will be most gratefully received.