The Florist and Pomologist, p. 52 (April 1881)

DOUBLE STOCKS.

M. CHATÉ has treated at some length on this interesting subject, in the Report of the International Congress of Botany and Horticulture, held in Paris during 1878, from which we select the following passages, which bear more or less on the causes which result in the production of double flowers in the Stock, under the French and German modes of treatment, respectively:—

The Germans, M. Chaté observes, who have had the monopoly of the production of Stock seeds, cultivate the plants in pots placed on shelves near the glass in well ventilated greenhouses; they give them only enough water to keep them alive, and prevent the growth of any branches after the first. The result of this mode of culture, according to my experience, is that the plant bears few seed-pods; they are small, and contain but few seeds. The seeds ripen equally, but this method has the inconvenience of being expensive and unnatural, although it produces good results.

According to the French method, the seedlings, after being wintered in pots in cool, well-aired frames, are planted in the open ground in a dry soil during the latter half of March, weather permitting, at the foot of a wall exposed to the morning sun. At the blooming period, the flower spikes are pinched off so as to leave only ten or twelve seed-pods on the central, and four or five on the lateral racemes, all the other branches being carefully cut away. There is no fear of the growth of further branches, if they are kept dry during the development of the seeds. The seeds of the perpetual Stock, which is cultivated in Paris under the name Parisian, render by this mode of culture 60 to 70 per cent. of plants with double flowers. At the time of taking the seeds from the pods, this first result may be exceeded by cutting off the upper fourth of the spike, by which proceeding the proportion of double-flowered plants is increased to from 80 to 85 per cent.

I advise persons wishing to cultivate these plants to leave, at the time of pricking-out, all the smallest plants; the plants with double flowers have much longer leaves than those with simple flowers, and as it is easy to preserve those which have the longest leaves, a large proportion of plants with simple flowers will thus be left.

As to the influence of old seeds on doubling, M. Chaté has noticed that the plants springing from two and three-year-old seeds are the dwarfest; the leaves are fewer in number, larger and thicker, and they bloom later; the spikes, thicker and shorter, are made up of flowers of such fullness that they are close and compact, and have the appearance of being more double. The colours are brighter and clearer than those of the plants springing from the seeds of the same year.

To sum up the different points in the culture of Stocks, it appears that the maturity of the seeds, the concentration of the sap in a certain number of seed-pods, and the judicious choice of plants as seed-bearers, are the most important means of obtaining double varieties in this genus.

M. Chaté, on a subsequent occasion, showed plants of the Parisian Stocks, some with double and some with single flowers, and made the following remarks concerning them:—

The characteristics of the single ones are darker green leaves, longer and smoother, the centre is well open and cup-shaped, the habit dwarfer, and the leaves very thickly set. Those with double flowers, on the contrary, have long, downy leaves; the small ones in the centre are twisted or rolled up, and covered with whitish hairs. These are very distinct characteristics, for those whose business it is to rogue the Stocks.

In the two specimens of Parisian Stocks with their seed-pods, the first has been pinched in the way I have mentioned, the other has been left to Nature. In the first, which has been pinched, there are about 250 or 300 seeds, which will produce 70 to 75 per cent. of Stocks with double flowers; in the second, we may reckon that there are from 1,200 to 1,500 seeds, which will give 75 to 80 per cent. of Stocks with single flowers. Thus we see the advantage of the French plan.

From the use of these different methods, we may conclude that the duplication is the direct result of excessive health, since the more the sap has been concentrated on a small number of seed-pods and seeds, the more double flowers are obtained.