This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
The Primrose requires the same cultural routine as that advised for the Polyanthus, and there are many choice varieties worthy of careful cultivation, their habits being both dissimilar and characteristic, independent of other attractive merits.
The following selection may be relied upon as being superior for pot-culture: - Primula Japonica, in variety. P. verticillata, half-hardy, a most profuse blooming and distinct form; the foliage is dusted densely over with white powder, as also the flower-stalks; flowers small, rich sulphur-yellow, borne in pointed spikes from six inches to a foot high; flowers under glass in April and May. P. cortusoides, P. cortusoides alba, P. cortusoides amcena, and P. cortusoides amoena alba. There are two varieties of this white, one a mere weed, the other handsome and beautiful in its flowers, which are in appearance like immense snowflakes, with almost the texture of Bouvardia jasminoides in petal: P. nivalis, P. spectabilis. Of the old doubles I need say little: enough that we know that there are double yellow, double crimson, white, lilac, and other shades, all doubles. A. Kerr.