MANURES FOR ORCHIDS

It should be distinctly understood that, in the case of true epiphytes, there is no need for manures, and, that artificial chemical manures are almost certain to bring about disastrous results, the final collapse being in proportion to the potency of the stimulant used and the recklessness of the grower. Where rain-water can be obtained and stored for use throughout the season, it is safest and most satisfactory to rely on this alone, except for some terrestrial Orchids. The chief difficulty in recommending the use of manures for any class of plants, Orchids especially, is in the fact that, once the practice is commenced, even those cultivators who begin cautiously frequently lose discretion in the course of time and ruin their plants by excessive applications. It is for this reason that the growers of plants for market purposes, whose secret of success almost entirely depends on the use of manures, are careful to give out the supplies to the men who have to use them, or, with the very best intentions, they would often destroy a crop. Indeed, it is not uncommon for foremen, or men in charge of departments in large nurseries devoted to growing plants for market, to resort to unfair means to get extra supplies of manure for their plants, and frequently with bad results. There is another curious feature about the use of manures in market-plant gardens, namely, that all concerned observe the greatest secrecy in the matter, and rarely admit that they use "anything but water"—that being the common expression. The same secrecy is observed by the Orchid expert in most cases. Another thing is that there is no common formula accepted by all practitioners. Each seems to have his own opinions as to materials, quality, and strength of the stimulants used.

One thing is certain, that even where artificial manures are used, the time of application and its discontinuance has more to do with success or failure than the nature of the manure itself. Even in cases where the administration of a mild stimulant is of use during the period of active growth and free rooting, if the manure is not discontinued after growth is completed much mischief is done.

It is not necessary to go into the relative merits of chemical manures, which are not recommended for use, but it may be stated that some growers do use small quantities with apparently good results, restricting the use of the manure to the active growing season and during the time the flower-spikes are forming. Aërides, Saccolabiums, and Vandas seem to be exceptions, as they represent the highest development of the epiphyte. Odontoglossums and some similar Orchids have been treated to a very small quantity of Peruvian guano sprinkled in the water used for watering them in spring while the flowers were forming, and without a bad effect; but the quantity used was very small, and the water was not allowed to touch the leaves or pseudo-bulbs. One grower on the Continent was in the habit of sprinkling a handful of nitrate of soda in the gutter of the house, especially before, or during heavy rain, in order that a little solution of it might be carried into the rain-water tanks in the Orchid house. His plants throve well, and this shows that even with epiphytal Orchids there is a field open for experiment; but the operator must not lose sight of the fact that he is "playing with edged tools." We will now state what has been proved to be beneficial when carefully carried out. Those who grow batches of the showy Dendrobiums such as D. nobile, D. Wardianum, D. Phalænopsis, and others of the class, and who, at the growing season, place them in a warm, moist house, suspended from the roof for preference, frequently give them weak doses of liquid manure during the season of growth, and the plants make very fine growth.

PLATE IV
CATTLEYA TRIANÆ
Var. "Hydra"
(The plant bore 88 flowers.)

The liquid from farm-yard manure, or from a stable, should be avoided, as its strength cannot be known; sometimes it is very weak, and at others fatally strong. A large tub with liquid manure made of cow-dung, and in which a coarse bag of soot has been sunk, is a safe manure for any plant, and if properly diluted can do no harm to plants requiring such a stimulant.

Terrestrial Orchids such as Calanthes and Phaius can scarcely be grown to their best without a liberal application of this, or some other manure known to the operator to be safe, during their season of growth. Cymbidiums, Zygopetalums, Peristerias, and other strong-growing Orchids have also been treated to weak liquid manure from the commencement of growth until the flowers expanded, with advantage so far as evidence is available.

An occasional watering of liquid manure, or slight sprinkling of guano, may be given beneath the staging in the evenings during the growing season.

The structure of the roots of Orchids does not favour the idea that they are suited for taking up stimulating liquid in the manner common to fibrous-rooted plants.

On the general question of the use of stimulants in Orchid culture many clever men have carried out experiments. The late Dr. A. H. Smee went into the question, basing his experiments on the chemical constituents of the plants themselves, which is not an infallible guide.

The late Norman C. Cookson carefully studied the subject, and he recommended for experiment the following formula:—

Potassium nitrate (saltpetre),3 oz.
Ammonium phosphate,2 oz.

Dissolve in a three-gallon jar of soft water, and when watering growing Orchids, or those perfecting their flowers, add one ounce of the solution to each gallon of water.

Again it must be urged that those experimenting with manures must do so only on growing plants, and when growth is completed it must be stopped. No Orchid grower should undertake such experiments without first obtaining his employer's concurrence.