Seed preparation
Collect hips soon after they colour. Cut them open, remove the hard seeds (achenes) and wash off the pulp and hairs; soak dried hips first to soften them. Floating seeds in water helps separate empty ones.

Fruit shrub growing guide
Dog rose seed is doubly dormant: it needs about two months of warmth and then about two months of cold before it will sprout. Give it both, or sow outdoors in summer or autumn and let the seasons do the work.
Collect hips soon after they colour. Cut them open, remove the hard seeds (achenes) and wash off the pulp and hairs; soak dried hips first to soften them. Floating seeds in water helps separate empty ones.
Not needed for dog rose: the USDA treatments use warm and cold stratification only. Acid treatment is described only for a few other rose species.
Essential, in two stages. Mix seed with moist sand or peat in a bag: keep it at about 20 °C (68 °F) for 60 days, then at about 4 °C (39 °F) in a refrigerator for 60 days. This gave 47% germination in the USDA data; much longer treatment (90 + 150 days) did not do better.
Only to soften dried hips before cleaning; the seed itself needs no soaking.
After stratification sow into cool to mild conditions. Outdoors, sow in summer (warm then cold through autumn and winter) or in autumn (cold only); seedlings appear in spring. In hot lowland climates do the cold stage in a refrigerator and sow in the coolest months.
5-10 mm (0.2-0.4 in), depending on seed size.
A free-draining seed compost or sandy seedbed. Outdoors, mulch the bed over winter to stop drying and frost heave.
Keep evenly moist through stratification and after sowing; check bags every few weeks.
No light is needed under the cover; give seedlings full sun.
Stratified seed sown in spring emerges as the weather warms; seed sown outdoors in summer or autumn comes up the following spring. Germination is uneven and some rose seed waits a second spring, so keep pots for another year before giving up.
Move seedlings into individual pots once they have a few true leaves.
Container seedlings are usually ready 3-5 months after germination. Plant in a sunny spot in well-drained soil, at the depth they grew in the pot.
Keep young plants watered in dry spells and weed-free. Dog rose becomes a large, arching, thorny shrub, so leave room.
The simplest method is to sow cleaned seed outdoors in pots in summer or autumn and wait for spring.
Dog rose is a temperate shrub native to Europe, North Africa and Central Asia to Pakistan. In India it suits the hills and cooler regions better than the hot plains.
If you want a known plant quickly, take cuttings; roses root readily from them.
Pick hips when they have changed colour fully. For eating, remove the seeds and the irritating hairs inside.
Give dog rose seed a warm then a cold period and it will sprout in spring.
They have double dormancy. They need about two months moist and warm, then about two months moist and cold, before they germinate.
Cold alone works poorly for dog rose. Give a warm stage at about 20 °C (68 °F) first, then the cold stage at about 4 °C (39 °F).
Seed can be stratified in a refrigerator anywhere, but dog rose grows best in temperate or hill climates.