Primula japonica in bloom.
image by Stan Shebs:commons.wikimedia.org
The primrose plant family, known botanically as primula, is made up of low-growing flowering perennials. Bloom shape, size and color vary, but most flower from mid-spring through mid-summer and are hardy in zones 4a to 8b. Beyond their cold hardiness zone they are grown as annuals. Primrose is commonly planted in beds, borders, containers and window boxes for its fresh green foliage and vibrant blooms. You will also often see it planted en masse in commercial landscaping.
Plant your primrose in a partial shade setting with morning sun and afternoon shade being the ideal mix of exposures. Provide a nutrient-rich soil that can hold moisture well without being soggy. Primroses prefer a slightly acidic to neutral soil, so if your soil is alkaline, till in a pound or two of peat moss to bring it back towards neutral. Amend planting soil with compost and well-aged manure to boost the nutrient levels if need be.
Water your primrose plants at their base under the leaves regularly so that the soil always feels moist to the touch and is never allowed to dry out. Depending on the season and the planting location, daily watering may be required in some climates. Mulch all around the base of your primrose plants with shredded bark, compost, cocoa hulls or leaf mold to hold moisture into the soil and control weeds.
Prune primrose only as needed to remove spent blooms or a damaged or dying leaf. Cut dead leaves off at the base of the plant if they do not come off with the gentlest tug. The bloom stems are tine so your hands can be the best tools to pinch off the spent bloom and keep the flower spike and plant looking tidy.
Feed your primroses once a month throughout the growing season with a water-soluble general purpose fertilizer for flowering plants such as MiracleGro or Schultz's. Apply according to the label dosing over wet soil. Alternatively, use a slow release granular fertilizer once or twice a season by scratching it into the soil around the plant and watering it well.