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.
When the plants are thus potted, and especially potted low down, an open situation in the garden is selected that is convenient for watering. A good hard and level bottom should be secured, or, if soft beneath, pieces of slate should be used to place the pots upon, to exclude the worms. Here the plants should be placed at proper distances from each other to admit of growth without crowding, and then filled in all round to the brim of the pots with ashes or some other good plunging material, so that the roots are thus protected from the force of the sun's rays, and consequent drought and exhaustion. The bedding Pelargonium can bear almost any amount of solar heat with impunity if its roots are kept moist and cool. As I usually put my plants in the open air at the end of May, and get them under glass from a week to ten days only before showing, they thus get about three months of thorough exposure to the weather, and are as dwarf and short-pointed as could possibly be wished. Of course the process of stopping has not been neglected, but rather has been maintained with constant regularity, every strong shoot having its extremity nipped out as fast as it had made three or four joints, care being taken also to encourage the centre growth, so as to secure a somewhat rounded form.
An occasional turning round the plants will also facilitate the production of a good shape. Pinching out all points and flower-buds is rigidly continued until within one month of the time of showing, when the process is discontinued, and the plants are allowed to grow away as freely as they please.
As a result of all this careful attention and exposure, the grower will find that he has a lot of robust dwarfy bushy plants that will now commence to throw up a mass of flower well above the foliage, that will, when expanded, need but the finish of a week or so under glass to make them perfect specimens. There are no yellow or discoloured leaves to be seen, all is fresh and vigorous; and the plants, after they have brought the highest honours at the show, will, with a little attention, make a greenhouse or conservatory look very gay indeed nearly up to Christmas.
The Zonal Pelargonium is naturally a gross feeder, and will take up an abundance of strong diet. The use of such material, however, to plants in the open ground would have a most undesirable tendency. This objection does not exist in the case of pot-plants, as the roots being confined within a contracted space, are necessarily subject to different conditions, and need stimulants to maintain that free growth so essential to the production of good specimens. Any application of liquid manure is scarcely needed until the flowering-pots have become filled with a mass of roots; but when such is the case - and that would probably result in about six weeks from potting - then a watering of a weak mixture twice a-week is desirable; and this dose may be increased in strength when the bloom is allowed to come up, as the claim on the resources of the plants will be proportionately increased. Horse-droppings well soaked in water usually make good liquid manure, and even stronger stuff than that may be used, such as guano-water, drainings from cow-sheds, and even from the closet cesspool, as I have used this latter during the past summer in the proportion of one bucketful to about five of water with the best results.
Amateur growers especially may take my word for it that they will secure better specimen plants in moderate-sized pots with a free use of liquid manure than they can obtain in large pots under any conditions, besides the credit of having produced as good or even better results in small pots than their fellow-competitors have realised in large ones.
Readers will have observed that I have not proposed the tying down or pegging of the plants in any way, and I say certainly not, as all these processes are to me highly objectionable. I do strongly contend that it should be the object and purpose of all exhibitors to produce specimen plants that have been as little as possible subjected to training with ties or sticks in any shape or fashion. Especially does this apply to the Zonal Pelargonium, as training of any description other than that induced by stopping is both unnecessary and absurd. I have now ready for show on the date that this issues from the press a fine lot of dwarf compact plants, with close rounded heads, each about 24 inches in diameter, and which will be larger still in a few weeks hence. Flower-stems are being thrown up all over them, and I have every reason to be satisfied with the prospect. The treatment that is here so strongly recommended for the Zonal section bears with equal force to the growth of the Nosegays, with the exception that some of the latter require less pinching, otherwise I make no distinction as to treatment. The double Pelargoniums are now rapidly becoming popular, and have become at many shows a class of themselves; and exceedingly attractive they are when well-grown specimens.
With these pinching must be performed with rather more moderation, but should still be carefully attended to, otherwise the plants will soon become leggy. If well looked after and grown as herein described, plants as dwarf and compact and almost as free of flower as the single varieties can easily be produced.
Heartily commending what is here written to the readers of the 'Gardener,' I shall conclude with a list of twelve good show Zonals, the same number of Nosegays, and six double-flowering Pelargoniums, all of which will well repay good cultivation.
Beaute" des Suresnes.
Grand Duke. Violet Hill Nosegay. Chilwell Beauty. Gathorne Hardy. Celestial. International. Eclat. Emmeline. Dr Hogg.
Triomphe de Stella. Pink Globe. Mrs Laing.
Wilhelm Pfitzer. Gloire de Nancy.
Andrew Henderson. Victor Lemoine.
Madame Lemoine. Marie Lemoine.