Helianthemum nummularium
Common Rock-rose · Rock Rose · Common Rock Rose
About the plant
What it is and where it grows — not part of any germination protocol.
The plant
- Habit
- Herbaceous perennialPlant Finder
- Habit
- subshrubPlants of the World Online
- Height
- 0.5-1 ft15-30 cmPlant Finder
- Spread
- 2-3 ft60-90 cmPlant Finder
- Flower
- Showy; pastel pink or yellowPlant Finder
- Blooms
- May to JunePlant Finder
- Native range
- Western Asia, EuropePlant Finder
- Hardiness zones
- 5-7Plant Finder
Growing conditions
- Sun
- Full sunPlant Finder
- Watering
- DryPlant Finder
Toxicity is noted only where a source states it. No note here is not a finding of safety.
Sources: Plant Finder — Missouri Botanical Garden; Plants of the World Online — Royal Botanic Gardens, Kew.
This source reports two treatments. Both are shown.
Protocol 1
DerivedN. C. Deno, 1993Difficulty High
Start around March 22, 2027 for a May 3 last frost.
Cold moist stratification
Temperature: 40°F 4°C
Three seeds of fifteen, in the 2nd week.
Germination happens during step 1, in 14 days.
20% germination in 14 days.
Three times the warm sowing, and it happens in the cold.
Protocol 2
DerivedN. C. Deno, 1993Start around March 20, 2027 for a May 3 last frost.
Warm moist stratification
Temperature: 70°F 21°C
One seed of fifteen, on the 16th day.
Cold moist stratification
Temperature: 40°F 4°C
Warm moist stratification
Temperature: 70°F 21°C
Germination happens during step 3, in 16 days.
7% germination in 16 days.
This source doesn't state how long steps 1 and 2 last.
How each step is done, in Deno’s words, and what Verified and Derived mean.
Germination trials
Readers’ own records of sowing this species, published after review. Share your trial · All trials
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