Companion Plants: Primula japonica
Windsor Junction, Nova Scotia, Canada
Reprinted from the Rhododendron Society of Canada Atlantic Newsletter
Primula japonica is one of a group often called "candelabra primula." The name comes from the arrangement of the flower stems. The flowers are arranged in layers or tiers around a tall stem. Each layer blooms in turn from the bottom to the top. Some have as many as six levels which spread the bloom period over several weeks.
This primula is the best known and most common of this group. A Japanese species, it is hardy and easy to grow. It likes moisture and grows best in a rich acid soil with lots of peat moss or leaf mould. It is a good plant for damp woodland or a shady border.
The plants are large and vigorous, leaves can be over a foot long, and the flower stalks may be over 2 feet tall. A fully mature plant might cover a 2-foot circle. So, if you grow them leave lots of room between the plants. They may need to be divided every few years to maintain good health. I prefer to do this in early spring.
The most common flower colour is a purplish-red with blooms up to an inch wide. A good white form ('Potsford's White') and some selected red strains ('Miller's Crimson' or 'Valley Red') are available from seed. Seed labeled Primula japonica may yield plants with many colour variations. They germinate freely in the garden and hundreds of seedlings will pop up each spring. Only the best shades should be saved and allowed to set seed. A clump of these primulas will add a splash of colour to the early summer garden.
In the winter it dies back to a large bud. As the weather gets cold, the thick roots contract and actually pull the bud below the soil surface. These buds are likely to rot if they are subjected to too much wet during the winter. Planting on a slope, where excess water can run off, will help them to survive our early spring freeze/thaw cycles.
Other candelabras to try are P. chungensis, P. beesiana, or P. pulverulenta. During their growing season these plants like quite a lot of moisture. In fact, they are often called "bog primulas" and are a prominent feature of what British gardeners call the damp garden. However, they will also grow in quite dry conditions if they have some shade. You can still enjoy them without a bog in your back yard.
Since these primulas seem to cross pollinate readily, most seedlings are likely to be hybrids.