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.
This lovely plant is not so much grown as it deserves to be for autumn and early winter flowering; its double white sweet-scented flowers are very valuable during the time named, and are useful for a variety of purposes, and much sought after by lovers of fragrant flowers. For room decoration it is invaluable; and nice plants can be grown in 4-inch pots, suitable for small vases, containing from two to four heads of bloom. When well grown, it can be kept within reasonable bounds in the size of pot named. Small specimens can be produced not more than 8 and 9 inches high, which, with its bold foliage, renders it a striking object. Of course larger specimens can be produced if the cultivator thinks it necessary. Their size entirely depends upon the time the plants are propagated, or if old plants are grown on from the commencement of the year. This plant can be bloomed with impunity two or three times in the season; but this with small plants is not advisable, especially when preparing them for winter work. There is too frequently a great mistake made in growing this Clerodendron in the stove amongst a collection of plants.
In this position it soon becomes tall and naked, and too often the picture of ill-health, as well as a prey to all insects that infest plants.
The plants are propagated any time from April to the beginning of June from cuttings, which strike very freely if accommodated for a short time in the propagating-house or under the shade of Melons, etc.
After being rooted it should gradually be moved to cooler quarters. We have not yet tried it in cool pits during the summer, but in favourable years we believe it would do for a short time during the hottest part of the season. Stopping must be attended to, according to the time the cuttings are rooted and the progress the plants make afterwards: the earliest-rooted plants can be stopped two or three times; others, if only stopped once, generally throw two or more shoots, which produce as many heads of bloom. The last-rooted ones, if not pinched at all, are by no means to be despised if they only carry one head of flower and fine foliage down to the pot. This plant is in no way particular as to soil, but when in small pots should have a rich compost consisting of good loam and a seventh of manure, and sufficient coarse sand to keep the soil open. It is advisable to feed the plants liberally with liquid manure after the blooms commence to show: an occasional application of soot-water imparts to the foliage a fine dark blue, and assists the plants materially.
The old but useful Clerodendron fallax can be treated in a similar way, or raised from seed, and will produce a fine show of scarlet at this season of the year. W. B.