Published by Brian Wagner on 10/1/25 in “Growing Flowers from Seed.”
Primula denticulata (commonly known as the ‘Drumstick Primrose’) is native to high elevations in the Himalayan Mountains around Tibet and Bhutan. Its flowers form a spherical cluster (like a chicken drumstick) and are often presented in white, purple or crimson red. They are some of the earliest primroses to flower – in their native Himalayas they’re often seen pushing their flowers through the melting snow. Hardy to Zone 4, these herbaceous perennials often stay evergreen in milder climates.
Primulaceae species are almost always lovers of moisture and cool temperatures. These are no exception, but they will certainly prefer sunshine over shade if they can get it. Needless to say, if you have a cool climate and an area of your garden with part sun, these will be flowering as early as March in Zones 6 or 7.
Growing from Seed
Most Primulaceae have a non-deep physiological dormancy, and this species is no exception. Freshly harvested seeds will germinate better if cold stratified at 4C (40F) for one month and then sown at 15C (60F) with dim light. Avoid using a heat mat, as seeds may get pushed into a secondary dormancy (which is very common in seeds that have a non-deep physiological dormancy). They should germinate in 4 or 5 days.
If you have seeds that are older, they will germinate without cold stratification. This loss of dormancy from dry storage over time is called after-ripening, and which is a common feature of the non-deep PD type of dormancy. Simply sow them around 15C (60F) to 21C (70F), but avoid going higher than this. They will germinate within a week.
Seedlings should be kept cool, and they will likely need 3 or 4 months to grow before ready for planting outside. Care should be taken to avoid planting in the high heat of summer. If possible, start seeds in November, pot up in January, and plant out in March. If they’re planted outside when it’s cooler (around 10C or 50F) they’ll be much happier. Some might flower in their first year, but most likely they will need to experience their first winter before they flower.
References
Abdalla ST, McKelvie AD. The interaction of chilling and gibberellic acid on the germination of seeds of ornamental plants. Seed Science and Technology. 1980; 8(2): 139-144.
Barton LV. Germination of Seeds. The Scientific Monthly. 1940 Dec 1;51(6):542-4.
Baskin CC, Baskin JM. Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination. Second Edition. 2014. Academic Press: San Diego, California
Deno N. Seed Germination Theory and Practice. Second Edition. 1993. Self-Published. Available online by the United States Department of Agriculture at http://naldc.nal.usda.gov/catalog/41278
Hitchmough J, Innes S, Mitschunas N. The effect of seed treatment and depth of sowing on seedling emergence in Primula species. Seed Science and Technology. 2011 Oct 1;39(3):539-51.
Xu KC, Jiang Z. Variations in seed morphology and germination of Primula denticulata along elevational gradients in the mountains of southwestern Yunnan. Chinese Journal of Plant Ecology. 2025; 49(7): 1119-1127.