Primula clarkei

Tight clumps of early pink. A tiny one for troughs... Flowers look the same as others, but these have stems or petioles. The native range of this species is Western Himalayas, but the plant is best grown in a pot or trough due to its diminutive size. Bright pink flowers appear very early spring. Perfect for a miniature garden. 3-5cm. Moist and cool. Deciduous.

P. clarkei has more rounded leaves and is a tighter clump, whereas P. warshenewskyana is a runner. Check them both out. 

Ettrig, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons