Seed Germination of Wild and Cultivated Roses
by Patricia S. Holloway, Associate Professor of Horticulture
Rose species vary in their seed germination requirements. Nearly all species
germinate best with a period of cold stratification, while others benefit from a
warm stratification period followed by cold stratification. Below is a general
outline of some methods for germinating rose seeds. Keep in mind that each batch
of seeds will vary in germinability based on growing conditions during seed
maturation, seed ripeness, seed storage time and presence of disease or insect
pests.
- Harvest rose hips that have just begun to turn red or orange and before
the pulp becomes soft.
- Seeds from just a few hips can be extracted by hand by cutting into each
hip and digging out the seeds. Larger quantities require maceration and
floatation. Soften the hips in a container of water for 1—2 days at room
temperature. Macerate the hips by rubbing them against a metal screen or
soil sieve or mixing in a blender with water. (Caution: blenders can injure
seeds if run too long.) Wash the pulp thoroughly, and most seeds will float
to the top where they can be separated from the heavier hips. The cleaner
the seeds, the less contamination you will get during germination.
- Dry the seeds on absorbent paper for 1–2 days.
- For most cultivated species and varieties of roses, mix the seeds into a
plastic bag containing moistened, clean, washed quartz sand or vermiculite.
Very clean sand or vermiculite are essential to avoid disease. It is
important that the seeds never dry out once they are put in the bag, but
avoid standing water. Seal the bag and place in a refrigerator at
approximately 4° C (40° F) for 4 months of cold stratification.
After stratification, remove the seeds from the sand or vermiculite by hand
or by sieving through a screen. DO NOT ALLOW SEEDS TO DRY OUT. Sow
immediately in a good potting soil or into prepared field soils.
- For wild rose, Rosa acicularis, seeds require a two-month period of
warm stratification followed by three months of cold stratification for
complete germination. The extracted, dried seeds can be mixed with sand or
vermiculite as outlined above or sown into flats of sterilized potting soil.
Keep the flats or bags at room temperature (approx. 21° C,
70° F) for two months of warm stratification. NEVER ALLOW THE SEEDS TO
DRY OUT! Move the flats or bags to a cold root cellar or refrigerator
(4° C, 40° F) for 3 months of cold stratification. Return the
flats to warm temperatures or remove the seeds from the sand or vermiculite
and sow in flats of potting soil. Seeds begin to germinate within 2 weeks.
If not enough seeds have germinated after 30 days, try repeating the cold
stratification for 30 days, and return to warm temperatures. Repeat the
cold/warm cycle until most seeds germinate.
This article was originally published in the Georgeson Botanical Notes No.
25, February 1996, published by the Georgeson Botanical Garden in Fairbanks. ©1996
This article was reprinted in the Fall/Winter 1997 issue of The Alaska Rose,
newsletter of the Alaska Rose Society.
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