This section is from the book "The Gardener V1", 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 plants belonging to this genus are elegant evergreen dwarf shrubs; the majority of them are of a compact habit of growth, forming handsome symmetrical specimens without the aid of stakes or other supports. In this country their flowering season is during the spring and early summer months. The flowers are borne on the points of the shoots, and when the plants are healthy almost every shoot will produce flowers.
At one time several species of the Pimelea were to be seen in all places where plant-growing was carried on with spirit in this country. At the present time, however, it is only from a few plant-exhibitors that the Pimelea receives the amount of care and attention that its beauty as a flowering-plant deserves. Three or four species of Pimelea rank amongst the very best of plants for exhibition purposes; hence, as a rule, we see one or other of them in the winning collections at our spring and summer flower-shows. Their merits, however, are not confined to the exhibition table, as they are very useful and highly effective when used for the decoration of the greenhouse or conservatory, and whether of a large or comparatively small size, are valuable for the latter purposes. One thing that should cause the species of Pimelea named at the end of this paper to be more generally cultivated than they are at present, is that they are not difficult to manage, their cultural requirements in all stages of their growth being simple, and easily attended to by any one who takes an interest in plant-culture. To succeed, however, in growing these plants successfully, the cultivator must supply them in due time with whatever is essential to their wellbeing, otherwise the growth of the plants will be unsatisfactory to him.
It matters not how simple the conditions necessary to success in the cultivation of any plants are - unless they are supplied at the right time, the plants will suffer in health through the omission; and plants of the Pimelea are no exception to this rule.
Points to be observed in the culture of the Pimelea are, that the plants in all stages of their growth should be placed in an airy position as near to the glass as possible, and should not be shaded except when in flower, or in the case of extra bright sunshine. They should be kept free from insects at all seasons. Red-spider, however, is the only insect that affects them seriously, and it must be kept down by occasionally syringing the plants with cold water in which a little soft-soap has been dissolved. The plants must not suffer from want of water at the roots, neither must the soil about the roots become saturated or "soured" by an over-supply of water or defective drainage. Hence, in the matter of watering, the cultivator should exercise considerable care, and only give sufficient for the requirements of the plants at the different stages or seasons of their growth.
Once in two years is often enough to repot established plants of the Pimelea, and the time to do so is soon after they have done flowering for the season. When they become large, they will, with the assistance of weak liquid-manure, given once a-week during the season of active growth, remain healthy and flower abundantly for several years without repotting. The Pimelea succeeds in a compost of peat and sand, or in one of loam and sand, in the proportion of 3 parts in bulk of the former to 1 of the latter. Peat, however, of a good fibry kind, is, in my opinion preferable to loam in which to grow the Pimelea. Some cultivators recommend a mixture of peat and loam as compost for the Pimelea and several other hard-wooded plants; but I have never been able to discover the benefit arising from the practice, nor understand the theory on which it is recommended. When repotting the plants, they should be supplied with an adequate amount of drainage, and the fresh soil made as firm as possible during the process, remembering not to fill the pots over full.
The Pimelea is increased by seeds or cuttings, the latter being the method in general practice. Half-ripened shoots, about 2 inches long, inserted in silver sand and covered with a bell-glass, and treated in a similar way to Heath cuttings, root freely. It requires three or four years, however, from the time the cuttings are rooted until the plants are of a useful size; and consequently it is better to purchase plants in a flowering state from a nurseryman, than to raise them from either seeds or cuttings.
The five species of Pimelea named below are, in my opinion, the most desirable to cultivate, and when properly treated are sure to please the cultivator.
P. elegans. This species blooms in April and May. It is a strong grower, producing large heads of flower of a creamy-white colour.
P. decussata blooms from April to July. It is a very free-flowering species. The flowers are pink in colour, and the plant is a robust grower.
P. Neippergeana. This is a compact - growing species, with white flowers, and blooms in April and May.
P. Hendersonii. The flowers of this species resemble those of the former in colour, but they are not quite so large. It is a very desirable kind, however, and if kept free of red-spider, is a handsome and striking plant when in bloom. J. Hammond.