WHAT I THINK I KNOW ABOUT P. VIALII by Michael Plumb, summer 2010
Everyone is fascinated by the unlikely purple and red spires of Primula vialii, and they sell like hot-cakes whenever they appear in garden stores or markets. Yet some people say they are short-lived little beauties, and in the past I have had great difficulty making them live longer than one or two seasons. If you read pages 315-316 in Primula by John Richards, you will learn that this plant has apparently disappeared from the wild, so the only clues we have as to its natural growing conditions are observations by one or two early plant hunters, who may have seen the plant only once. Its history is also confused, as the early plant hunters made mistakes in identifying it. Because it now seems to have almost disappeared from its native home in Yunnan and Sichuan, we as gardeners have a responsibility to keep it thriving "in captivity".
I used to be puzzled by Richard's description in which he says the leaves are up to 30 cm (one foot!) long. Then one day (at a rose show, of all things) I saw one plant growing as a pond marginal, and it was massive. This summer I have kept my potted vialii soaking in a trough of water, sunk half-way up the sides of the pots, and they are thriving! And the addition of a dilute kelp solution definitely gave them a boost. Such wet conditions would kill most normal primula. Perhaps this answers the mystery of why they seem short-lived (Richards says, "It was originally considered a rather tricky species to grow...") - Your soil may not be boggy enough! And even if they are, in fact, short-lived plants, boggy soil should produce much healthier and larger plants. A thought - Perhaps the strain of P. vialii that has come down to us is from that wild seed that was taken from boggy meadows rather than from the plant's drier locations.
A second reason P. vialii may seem short-lived is that it remains dormant for about seven months, disappearing below the surface of the soil as a tiny resting bud during winter and a large part of spring, so it is extremely easy to dig the plants up by mistake.
Third, if you are over-wintering P. vialii in pots, the plants seem to disappear in dormancy, as I have just mentioned. Don't do what I did several years ago as a new grower of primula and throw the pots out, thinking the plants had died!
A different problem is that the plants may not produce a strong scape until their third year, and some of the plants may not bloom at all until their third year (One third of my original batch did not flower until this, their third year.). You will reap your full reward in the third year.
This may all seem a bit negative, but P. vialii is so lovely that it is worth the wait. Another bonus is that the seed remains viable for many years if it is kept cool. My batch was grown from John Kerridge's seed which must have been at least ten years old! So if you see P. vialii listed in our next Seed Exchange, don't hesitate to order some, as germination is very good. Just remember to keep the plants very wet in their leafy, non-dormant state, and fairly dry in winter (Snow covering is good).