This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The "Show" and "Decorative" Pelargoniums have been evolved from P. cucullatum and P. grandiflorum, and the "Fancy" kinds have probably had a similar origin. The garden varieties of the Show and Decorative section have large circular flowers, the two upper petals of which are blotched with a distinct colour. Thirty or forty years ago these were very popular plants, but they have gradually given way to the more vigorous Zonals. The "Fancy" Pelargoniums differ chiefly in having the margins of the petals crisped or wavy, and are marked in various ways. The leaves are less hairy, moderately lobed, and with sharper teeth than the Zonal section. Both sections are less easy to grow than other garden Pelargoniums, and are much more liable to damp off or rot during the winter; they are also very subject to attacks of aphides, and must be kept clean in the way recommended for the Ivy-leaved section. The plants are propagated from well-ripened cuttings of non-flowering shoots during July and August in a gritty loam in the same way as the Zonal varieties. The young plants, however, must be kept in a warm atmosphere during the winter and in the maximum amount of light. A little, but not too much, moisture is necessary, otherwise they are apt to rot off. In spring the plants are transferred to 5-in. or 6-in. pots, and when started well into growth the tops are pinched out to induce a bushy habit. Weak liquid manure or soot water applied occasionally is very beneficial, and keeps the foliage of a deep healthy green colour. Years ago large numbers of these Show and Fancy Pelargoniums were brought to Covent Garden from the neighbourhood of Tottenham and Edmonton, Mr. Beckwith of the former place being the largest grower in the kingdom at the time (fig. 294).
There are many species of Pelargoniums having deliciously scented foliage. Some, however, are rare and never likely to be grown in large quantities, while others are somewhat fastidious. The only species that is still grown, but not nearly so much as formerly, is P. querci-folium - the sweet-scented Oak-leaf Geranium. It is as easily grown as any Zonal, and has deeply lobed and divided leaves, sweetly scented, the flowers being small, purple or rose, with narrow petals. Besides the plants a limited trade is done in the foliage, the leaves being made up in bunches and sold for backing coat flowers, etc. The plants may be grown for years and will attain large proportions. Market growers, however, prefer them in 5-in. or 6-in. pots, and often cut the old ones hard back in the new year to make plenty of new growth during the season.
Fig. 294. - Show Pelargoniums.