A rare perennial wild flower native to a small area of northern Scotland, Scottish primrose (Primula scotica) is becoming increasingly rare since it blooms and sets seeds infrequently. Its natural habitat is a sandy, limestone turf near the coast, exposed to wind and abundant sunshine. Its bright green, loval leaves form a dwarf rosette no more than 4 inches tall and no more than 3 inches wide typically. In late spring to midsummer a central short flower stem arises, bearing one to six fragrant, purplish violet flowers with yellow throats. It needs a moist but acidic soil and tolerates shady garden conditions. Grow in outdoors in USDA hardiness zones 8 or 9, where summers are cool.
Sow seeds or young plants of Scottish primrose outdoors in spring. The American Horticultural Society's "A-Z Encyclopedia of Garden Plants" lists two cultural options for this delicate wild flower species. Plant them in full sun to partial shade in a moderately fertile, moist but well-drained soil that is rich in acidic humus. Alternatively, plant in a 50:50 peat and sand mixture that is evenly moist but well-draining, and is not alkaline in pH. If soil is kept moist at all time, this soil sustains the plants if in full sun.
Replenish humus to the plant by adding fresh acidic compost annually over the root zone. Shreds of live sphagnum moss, peat or coffee grounds lightly scratched into the soil surface acts as a natural fertiliser.
Water the Scottish primroses to maintain an evenly moist soil in all seasons. Air temperature water is best. Collected rainwater is much better than treated municipal water.
Create a soil mixture of equal parts soilless potting mix, peat or leaf moss and gritty sand. This is the growing medium for sowing both seeds and plants in a cool alpine greenhouse or cold frame. Temperature in this environment dips to -6.66 to 4.44 degrees C in winter, but no higher than 21.1 degrees C in the hottest days of summer.
Place the container in a partially sunny to full sun location in the alpine house or outdoor cold frame, keeping the soil evenly moist year round. Make sure the container has drainages holes in the bottom so the soil never becomes soggy.
Add 1/4 to 1/2 inch amounts of fresh acidic compost or shredded bits of live sphagnum moss atop the potted soil's surface in spring and fall. This organic matter degrades to provide nutrients to the plant roots.
Scottish primrose seed is extremely tiny and available from nursery companies online, especially those in the British Isles or with alpine or rare plant societies. Be patient as these seeds may take up to one to two years to germinate in less-than-perfect soil conditions.
Scottish primrose grows only in northern Scotland, and in sandy soils along the cool north coast. Too much summer warmth will degrade this wild flower. Humidity year round is OK, but wet soil or damp leaves can lead to fungal rot.