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.
I should recommend every one who has a conservatory to keep gay all the year round to patronise Iris reticulata. A dozen of pots are not too much to keep up a supply of it in bloom in winter. It is beautiful as any Orchid. It is a blue of indescribable richness, while each petal has a band of yellow down its centre. I. reticulata is most manageable in the forcing-house when not subject to strong fire-heat; a temperature of 60° by day and 5° less at night is sufficient. The most simple mode to cultivate them for this end is to lift the bulbs from the open ground in September and November, and to place them in 5-inch pots. The greatest proportion of the soil should be light rich fibry loam, with a little sand and old cow-manure. After potting, stand them in a cool house for a month, when they will have appeared above the soil, and their roots will have extended through the whole of the soil. "Water only to sustain the soil moderately moist up to this stage, but give a greater supply after they are put into force. Now do not try to outdo so-and-so - your neighbours, I mean - by an extravagant amount of fire-heat, else you will most assuredly only come off at the latest and worst.
So far at least as quality goes, rather conduct the forcing with quiet moderation, and success will be the result. Keep the atmosphere charged, but not overcharged, with moisture, with a gentle air floating imperceptibly amongst your plants. Transparent glass, of course, is most essential, both to produce stubby plants and rich well-coloured blooms. This applies to forcing flowers in general.
What a gem is that delightful species of Linum tryginum, and how pleasant it is to have its glorious rich golden cups in the middle of "gloomy winter," just after all the yellow of the Chrysanthemums has died out! But I may inform those of my readers who are unacquainted with it, that its flowers are of the brightest orange, with a skin silky and solid. They are produced in clusters on the apex of the shoots, and are somewhat campanulate in form; each corolla has five petals, and measures 1 1/2 inch in diameter. The leaves are ovate-lanceolate, simple, their greatest dimension being 2 inches, of the most pleasing pale glaucous green. It succeeds admirably with the same treatment as I. reticulata.
Eupatorium odoratum is a most useful old greenhouse plant, although some of the most fastidious have given it the cold shoulder. Its great umbels of sweet, white, Ageratum-like flowers, are a consideration in late autumn, when other flowers are most scarce. Then, again, its wants are so humble and simple - only a sunny aspect in the greenhouse, a shift of pots once a-year, and liberal supplies of water when the flower-crowns are in formation. It flowers most profusely when rather pot-bound, and is benefited by a little forcing. Not many of the Hyacinth tribe succeed well when put early into strong heat. I will not speak about that useful sweet little Roman white: three weeks gentle forcing gave us open flowers by the 26th October, certainly as fine in quality as are usually met with a month later. If I remember aright, the following half-dozen sorts exceeded all others that we tried to force early: La Precoce comes first with a plump but rather pretty spike of single white; next in course appears Prince Albert, a telling single blue; in close succession Homerus, a single red; tightly pressed by Anna Maria, double pinkish white; - Grand Vainqueur, single white; Regulus, lavender, shaded blue; and Carmoisie Royale, double red, come at the same time.
Hyacinths in hanging-baskets afford a most pleasing feature in a conservatory, and not less pleasing are many of the early Tulips and Crocus; the two latter are quite adapted to pierce the sides of the largest baskets and stud their mossy sides with their varied colours. I have planted hundreds in baskets this autumn as described. The Snowdrops are also acceptable companions to the other bulbs, but they rebel against all forcing beyond the mere protection of a glass cover.
While speaking about hanging-baskets, I may venture to describe, for the information of those of less experience, what we consider a good practice to carry out in their management, and at the same time enumerate a list of plants suitable to that purpose. Supposing, then, we take into hand baskets above the usual size, our method of filling them would be as follows, considering that all the necessary means are at hand: Green moss being one of the principal items employed, it should be of the finest and most substantial quality - that is to say, the more green and felty, the better to retain the soil properly, and make rich verdant sides. First place a large patch of moss over the bottom to form a foundation, then a portion of soil; next turn out some pots of various coloured Crocus, and divide the balls into two or more plants; then place alternately clumps of the several sorts around the sides of the basket, making only the crowns protrude beyond the wires, while the roots rest on the soil inside the basket. Besides the Crocus, a few Snowdrops may be introduced; they will come first into flower. Independent of bulbs, we have the basket to furnish with plants which give immediate effect; the better to accomplish this, the more diversified the selection should be.
Dwarf hardy Ferns should be largely employed, along with Lycopodiums and Alpines. Of Ferns, Davallias, Aspleniums, Polypodiums, amongst natives; and there is a rich variety to be had among hardy exotics. Of Lycopodiums, Dentic-ulata and D. variegata are the two best. Among Alpines, one can scarcely go wrong if they are dwarf, spreading, and evergreen. All the Sedums are applicable, particularly S. carnea variegata - it affords a most graceful drapery always fresh. Of Mesembryanthemums, M. lucanthemum and M. roseum are superior. Variegated Thymes look well; dwarf variegated grasses also. Of Mimulus, the musk variety is the best. Oxalis tropoeoloides, with its purple-brown leaves and yellow flowers, is striking. Aubrietia grandiflora variegata, A. del-toidea grandiflora, A. purpurea variegata, Bambusa Japonica variegata, to furnish the top, Centaurea argentea, are splendid in winter. Linnaea borealis, a truly lovely little plant, allied to the Honeysuckle, with slender trailing stems and fragrant pink-eyed bell-flowers. Lobelias of sorts, Myosotis rupicola, M. Palustris, Phlox Nelsonii, Saxifraga cymbalaria, S. hirculus, S. pectinata, S. Japonica variegata, etc. Besides Sedum carnea variegata, we must not forget S. atropurpureum.
S. Japonicum variegatum, S. Sieboldii, and Sempervivum Californicum, form nice rosettes; so does Echeveria secunda glauca. But I must stop and commence the building again. Just put in a circle of the nicest variegation to satisfy the eye in the mean time, and the bulbs will appear by-and-by to add to the beauty. All the plants having been put in, proceed to build the sides up with moss a bit before putting in more bulbs. Then follow the same process of bulbs and other plants, succeeded with tiers of moss until the top is reached, when Hyacinths and large Ferns and other flowering plants form part of the whole; and complete the work by covering the upper surface of the soil with moss. Finally, regarding watering and training, always supply enough water to wet the entire soil, and this more frequently than to a pot. Train by pegging in with hooks of wire any straggling growth, and distribute the shoots with an eye to lightsome grace. By the by, we must not omit to mention variegated Ivies, and that splendid species of Virginian creeper, Ampelopsis Veitchii. Nothing can surpass the last suspended in festoons over the basket; its pretty russet foliage is charming.
Leaving the things of mid-air, let us descend again and give our attention to those on terra Urma. In the number of the ' Gardener' for November, our Editor has characterised Acer negundo variegata as one of the most effective plants for the flower-garden. This can well be conceived if it looks only half as well outside as it does indoors, treated as a greenhouse plant; for, to say the least, it is simply magnificent, more especially when the plants have reached 6 or 8 feet in height, at which size they are suitable for grouping with large Camellias, when their presence most effectually lights up the gloom natural to a Camellia-house in summer, or amongst Rhododendrons in spring. Such plants are invaluable, particularly when associated with red or crimson sorts. Acer negundo variegata is a variegated form of Maple, and therefore deciduous. Under glass it retains its leaves six months - that is to say, treated as a greenhouse plant. The leaves are pinnate, forming lovely pendant plumes of cream-white and green, the white of the leaves and branches predominating frequently much beyond the green.
The best mode of cultivating it is to pot from the open ground in autumn, transferring them to a cool house until early spring, when they may be placed in gentle heat where the air is rather humid. Water copiously after signs of growth are apparent; little water is required in winter while yet the plants are dormant. What useful plants are Rockets, too, when grown in greenhouses ! Of the double Purple and double French-white, I have something favourable to announce. The duration and size of their grand spikes and flowers are what surprised me most, emitting and filling the air with the odour of the Stock over three months without a semblance of seediness in leaf or flower. These, like the intermediate Stock, ought never to be absent in spring and summer. All they require in a cultural sense is a roomy pot and loam rich with old cow-manure. Clumps lifted from the borders in autumn and placed in a greenhouse, good drainage, along with rather rich feeding by manure-water from the period vigorous growth commences until the first blossoms open, sum up their wants.
There are many other plants of equal interest which must stand over for the present. A. Kerr.