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.
A look through the collections of Show Pelargoniums when in bloom in the month of June gave the following as a selection of twenty-four fine varieties of great usefulness, whether for the decoration of the conservatory, or for the exhibition-table. A few of them are new flowers, most of them are varieties of the past three or four years, and all have been selected for their obvious good qualities. Alphabetically, our selection runs in the following order: Attraction (Foster), soft rosy lilac, novel and good; Bonnie Charlie (Hoyle), rosy crimson, with black top petals; Charles Turner (Hoyle), orange scarlet, rich dark upper petals, a grand flower of extra-fine quality; Claribel (Hoyle), a charming light variety, pure white, with a bright carmine spot on the top petals; Corsair (Foster), bright purple, with black top petals, a novel and fine flower; Conflagration (Foster), rich crimson, with black blotch on top petals; Diadem (Hoyle), rosy purple, with deep shading, rich dark top petals; Emily (Hoyle), delicate rose, large and fine; Empress (Foster), rose, with maroon spot on the top petals; Envoy (Hoyle), warm rose, with shaded dark top petals; Example (Hoyle), a grand flower, rich deep crimson rose, black top petals; Heirloom (Hoyle), rich orange rose, with large black blotch on top petals; Hermit (Beck), white, with large reddish maroon spot on top petals; Lady of the Lake (Foster), orange rose, very dark maroon top petals, a fine but rather late-blooming variety; Lilacina (Beck), a pleasing pale lilac-coloured flower, not of the best form, but charming for its hue of colour; Maid of Honour (Foster), light rosy pink, with small dark blotch on top petals; Marion (Foster), a noble flower, rose, with dark maroon top petals; Mary Hoyle (Hoyle), a beautiful flower, warm orange rose, small dark blotch on top petals lit up with bright orange ; Queen of Roses (Beck), lively purple, shaded with rose, new in colour, very attractive and free; Regina Formosa (Beck), rose, dark top petals; Royal Albert (Hoyle), warm rose lower petals, large dark blotch on top petals, a large and very fine flower; Sceur de Charite (Foster), rich painted orange lower petals, black top petals, a fine and striking flower; Sunbeam (Hoyle), rose lower petals, dark top petals, remarkably free blooming; Troubadour (Foster), lively orange pink, dark spot on upper petals, a fine and striking flower; and William Hoyle (Hoyle), a very dark variety, warm rose lower petals, tinted with orange and red, very fine, and novel in character.
Let us suppose that an order is given to a nurseryman for a dozen of these Pelargoniums for exhibition purposes. The best time to receive the plants would be in October. They should then be in 48-pots. As soon as received the plants should be gently syringed to clean them, the surface soil slightly stirred, and then placed in a light and airy position to recover the effects of the journey from the nursery. The plants should be well established, and if in vigorous growth will soon require a shift into the next-sized pot, using good yellow loam, enriched with some well-decomposed stable manure and the addition of some silver sand. Each plant should have the aid of a neat stake and air and light, and attention should be paid to watering ; and in a month's time the plants will be ready for a farther shift into a larger pot, in which they may remain until the end of January or beginning of February, when they should be placed in their blooming-pots, using them of a size suited to the strength of each plant. It is highly important for the cultivator to bear in mind that, as it is necessary the pots be well filled with roots by the time the plants come into bloom, they should not be overpotted, or they will make rank growth at the expense of flower.
As soon as the lower leaves show symptoms of turning yellow during the spring, a little stimulus will be requisite, and some clear weak manure water may be given with benefit, and be continued until the buds are nearly ready to expand. Anything like forcing should be avoided, but a little fire-heat will be beneficial in damp, dull, and foggy weather, and also whenever the temperature sinks to near 40°.
Cleanliness is a very important element in the culture of the Pelargonium. No dead foliage should be allowed to remain on the plants, and if the green leaves become dirty or dusty, they should be carefully washed. Lay it down as a general rule that health and cleanliness must be sedulously attended to, airing well even in winter, but avoiding cold draughts of air, and keeping the plants free from damp. No flower is more easily cultivated than the Pelargonium, probably none is more generally mismanaged.
At the blooming time some shade should be given to the flowers during bright, hot, sunny weather, to prolong the bloom, and prevent it from being scorched. Immediately after blooming, the plants should be placed out of doors on a spot not exposed to heavy rains, and water be sparingly given, so that the wood can become well ripened; for hard well-ripened wood is of the utmost value. After cutting down the plants, leaving a "bottom" corresponding to the size of the plant, they should be placed in a greenhouse or frame by themselves, and kept dry, and exposed to the sun and air, and protected from rain only. In about a month the buds will have pushed sufficiently to intimate that the plants should be repotted; they should then be shaken out of the pots, the whole of the soil removed, and the roots pruned, and be potted in small pots, kept in a close shaded frame for a few days, and gradually inured to the light, when more air may be given. In October, a shift should be made into the blooming-pots, an operation requiring some care, that the growing shoots be not rubbed off. Water but sparingly, and avoid wetting the foliage during the winter months.
When the growing season sets in, water thoroughly as the plants require it.
As specimens for exhibition require some management differing from that required for those plants intended for the decoration of the conservatory, some hints on this matter may not be unacceptable. In growing Pelargoniums for exhibition, experience is of the utmost value, while forethought is scarcely less important. Supposing a good head of blooms is required in May, there must be a judicious selection of plants for early work, and these should have their last shifts not later than the beginning of October, and by January the pots should be tolerably full of roots, and the plants have made strong growth. At this stage they require some encouragement, by putting on a little fire early in the afternoon, just sufficient to raise the temperature of the house; when warm, the flues or pipes can be syringed if the weather be open and fine. The steam rising from the pipes excites the plants to make growth, and as the season advances the plants should be encouraged to increase this. The shoots should be tied out singly, so as to admit light and air to every part of the plant.
As the season advances, water should be more freely given, but care must be taken not to make the soil too wet, so as to induce a weak sappy growth; air should be given on all favourable occasions, but cold draughts of air should not be allowed to play directly on the plants. Plants intended for exhibition in June, July, and August, should not be excited into growth so early as those intended for early showing; they should, however, receive their final shifts by the end of the year, and be gently grown, and heat should be given only on special occasions - as for instance, to exclude frost and dry the house, giving air at the same time. Early in January there should be the commencement of tying the plants into shape, as the old wood as well as the young can at this stage be twisted with less danger than later in the season, when it is full of sap. As before stated, care must be taken not to water the plants too freely, as it is not quick growth that is required so much as short strong shoots, which will insure fine flowers as well as a good head of bloom.
The later in the year the plants are required for exhibition purposes, the more valuable does experience become, and the greater necessity is there for the due exercise of forethought. There is no more valuable teacher than experience; perhaps there is scarcely a preceptor whose lessons are more disregarded by some - certainly not by successful exhibitors of the Show Pelargonium.