Half hardy bulbs for greenhouse

A large number of bulbs are available for the unheated greenhouse which are somewhat difficult to place, because they are suited neither to the warm house nor to the open garden. Many of these can resist even a few degrees of frost on occasion, but the rapid changes of our climate are more than they can endure. For such the greenhouse that can be kept just above freezing-point by temporary means is admirably adapted.

Planting time in some cases coincides with that of the earliest hardy bulbs, and, as they require to begin with much the same treatment, August is generally a busy month in the potting shed. Lachenalias and Freesias, two well-known groups of half-hardy bulbs, belong to this section. L. pendula flowers naturally in November ; consequently, it ripens its bulbs first in order, and to have its welcome spikes of bright light-crimson in due season-July is not too soon to pot this particular species. L. pendula is far too seldom grown, for it is one of the most precious flowers of early winter.

The genus includes a number of most charming species and hybrids which have been gradually coming more and more to the front, and the varied shades of colour in the flowers of different species are somewhat remarkable. L. pendula is, I believe, the only species of its peculiar shade of rose-red. The greater number are brilliant yellow, either self-coloured or touched with scarlet, and with more or less distinct purple blotches. One species, generally called L. tricolor, but more correctly L. luteola, has a good deal of green in the drooping bells, while another, L. ccerulea purpurea, shows a peculiar metallic blue on the spike of grey-white flowers, and in its best variety is very ornamental.

The most familiar of all hybrid forms is L. Nelsoni, raised now many years ago. It will always hold its own, but of late years these lovely Cape Cowslips, as they are sometimes called, have been skilfully taken in hand by Mr. F. W. Moore, the able curator of the Glasnevin Botanical Gardens, Dublin, and others, and have been brought to a high degree of perfection.

Lachenalias should be grown with as little artificial heat as possible, and nothing injures the flowering quality of these, or in fact of most bulbs, more than to let them start into root growth before they are potted. The routine of cultivation may be said to begin as they go out of flower. Water should then be given them sparingly, and after the leaves die down it must be withheld altogether. The pots may then be laid on their side on a warm shelf, where they will not be dripped upon, that the bulbs may ripen, for to be kept absolutely dry during their period of rest is essential.

The least moisture at this stage will start the ring of little white root-points into growth, in which case, it is better to re-pot them immediately. August is, however, the right month for re-potting all the kinds, L. pendula excepted, when they should be shaken out of the dry soil, sorted into three sizes and placed in their flowering pots without delay.

On this point, it is well to remember that any disturbance of the roots after potting and growth has once begun will seriously cripple the flowering power of the bulbs. The larger bulbs will give the finest spikes for pots ; the second size may be " boxed " and will give useful flowers for cutting ; the smallest, if the sort be valuable, will be worth saving for stock, but in any case they must be separated from the large bulbs.

Three weeks under ashes will generally suffice, and then a cold frame, open day and night, except in drenching rain, will be the best position until the frost, which seldom fails to come during the first week in October; then an additional thick mat will be needed, and the frame must be closed in the evening, but as much air as possible should be given during the day. It often happens that weeks of mild weather follow that first early frost, but let the leaves get once badly frosted, all the hopes of the year are lost as far as flowers are concerned. This open-air treatment, as far as it can be carried out, gives far better results with Lachenalias than coddling, and with many other half-hardy bulbs as well.

Several species of Lachenalia may be used with good effect as basket-plants. Freesias may be grown on the same lines, and stand up firmly on their wiry stems under cool treatment, instead of flopping about in the tiresome way they often do in heat. Never shall I forget a March day in a garden on the Aventine at Rome where Freesias reigned supreme. Under the Palms, bordering the shrubberies, indeed, everywhere, they reared their pretty heads and filled the air with sweetness.

With plenty of moisture at the root, dry air above, and with as much sun as our wintry skies will allow, they will do almost as well under a glass shelter, only frost must not touch them.

Somewhat in the same category come Ixias-so exquisite when they open wide their filmy, many-coloured tissues to the sunbeams. The taller Sparaxis pulcherrima, too, not often seen, but very beautiful, is a gem for the cold greenhouse. For hanging-pots or baskets the sulphur-coloured Oxalis cernua, sold now as the Bermuda Buttercup-on the principle that it comes from Madeira and is no Buttercup-is most ornamental.

Six of the bulbs, not very large at best, are quite enough for a good-sized basket, while three will be ample for a six-inch pot. Scarcely any plant plays more pranks with its roots than this species of Oxalis. The bulbs must be planted a good two inches or more below the rim of the pot to allow of earthing-up, otherwise the silvery white coils of tubers will shoulder themselves out in the oddest way, especially if, by chance, they are a little cramped for room. Turn out a pot a few weeks later and not a trace of these fleshy coils remain ; instead, if one looks closely, the rudimentary bulbs may be detected clinging to some of the fibrous roots. Later on, these will develop into shining brown " nuts," beloved of mice, for they will travel any distance to get them.

With the single exception of Lachenalia pendula, the half-hardy bulbs and tubers above detailed may be expected to bloom in March and April, and are, strictly speaking, spring-flowering, though with all such plants grown under shelter of glass a little experience teaches that they may be advanced or retarded with a little change of treatment-educated, in fact, to our wishes.

A little later, but in quick succession, to these come the early flowering Gladioli-G. ramosus and its congeners-from the dainty " Bride " (G. Colvillei albus), through a whole series of varieties with pink and scarlet flowers, prettily blotched with white. These are followed by the fine cherry-coloured spikes of G. Saundersi, which have only one failing-that their stems are too slender for the large flowers, and need support. Lemoine's hybrid strain has also many varieties, with flowers of cream and purple, which provide a useful change of colour. In southern countries, these Gladioli are hardy, and may be left in the open border during the winter, but for the present purpose they are placed more appropriately on the half-hardy list.

Alstromerias are now favourite border plants, but one of the most beautiful of them all, A. pelegrina alba, is more tender, requiring shelter, and is perhaps the only one suitable for pot culture. Alstromerias do best grown from seed, for the long thong-like roots are easily injured, and dislike removal. For this reason it is well to sow the seeds of this species in what is called a " Lily pot," deep and narrow in proportion-three or four seeds at most being enough for a 7-in. pot. This lovely plant, with its heads of white Lily-like flowers, freckled with palest green, will disappoint no one. It starts early into growth, and, like Lachenalias and other half-hardy bulbs, must not be frosted, but it is a typical plant for the cold greenhouse, as it invariably shows signs of distress in too great warmth by losing its leaves.

Probably most people would wish to grow Callas, but they are somewhat more tender than might be supposed, for the leaves are disfigured by the slightest touch of frost. They are quite safe, however, in a low temperature, provided it does not touch 35°.

The dainty little climbing Tropmolums, not always recognised as tuberous plants, should not be overlooked, as they also add an entirely distinct feature to the greenhouse in early spring. T. tricolorum Jarratti is the best known species, and is often grown upon a balloon trellis. In a small unheated conservatory I once had a narrow piece of wired wall between two windows which every spring was draped with its brilliant scarlet and black flowers, and was the admiration of all beholders. T. brachyceras, with small butterfly-like yellow flowers, has the same habit, and trains itself to upright wires in much the same fashion, both of them hanging out many slender branchlets in natural festoons.

Almost any form of trellis, or even a support of slight twigs, is better than the stiff artificial wire balloon so beloved of some gardeners. T. azureum, with its slender blue flowers, is only seldom met with, but it is a very gem of its kind, and quite as easy to grow as the others, and the three are so entirely distinct that it is well to grow them all.

The tubers increase quickly. Two or three new ones will generally be found on turning out the pots, and the original tuber will exist for years, growing larger and larger. A cultural hint may be found of use. It is better to shake the tubers out of the soil very soon after the foliage and stems are dead and dry and to pot at once for the next year's flowering. The usual plan is to put them carefully away until the autumn, but they have a habit of taking their owner unawares and sending out a long, straggling wire-like shoot, difficult to disentangle and easily broken-an injury irreparable for the season. If kept quite dry they will not start any the sooner for being potted, but a watchful eye must be kept upon their movements in early autumn, so that a support of some kind may be supplied in good time.

The greenhouse must not be left tenantless in summer, however, and an infinity of miscellaneous kinds remain to be mentioned, like Arthropodium paniculatum, charming both in flower and leafage, Veltheimia viridifolia, some of the Ornithogalums, Watsonias, and Lilies-one of the most important groups of all, which must presently be taken into consideration by themselves. Iris fimbriata, not much grown and of unusual type, may here be recommended.

The pale, drooping, evergreen leaves resemble a broad-leaved grass, and are at all times graceful, and the pale-blue crested flowers which appear in May and June might be some delicately tinted Orchid. Full exposure to sun and air and generous treatment during the summer will probably overcome the shyness to flower of which this beautiful Chinese species is sometimes accused. Later in the year we may have Nerines, another genus of Cape bulbs, represented by the well-known Guernsey Lily, which, being autumn flowering, require rather different treatment. The essential point with these is the summer roasting while the bulbs are at rest. A hot shelf near the glass, where they will not get a drop of water, is the most suitable position as soon as the leaves have died down. At the end of August or in September, for they are somewhat uncertain, the flower scapes begin to show, coming before the leaves, therefore one must be prepared with good greenery to group with them.

These gorgeous Amaryllids, crimson, scarlet, and cherry-pink, according to their species, are amongst the most valuable of autumn flowers for the greenhouse. The pretty little N. undulata, with pale-pink crimped petals, though not showy, is very attractive, and the flower-heads of all the kinds are long-lasting. The flowering, however, depends not only on the care taken of the bulbs in summer, but of the foliage, and herein lies the difficulty of growing Nerines without a good working greenhouse or frame devoted to such things as must be kept from frost. Out of flower, they are not particularly ornamental, but leaf growth must then be encouraged, and they must be kept growing all through the winter.

One difference between the treatment of Nerines and most other bulbs is that they resent re-potting. It is better to leave them alone until by natural increase the bulbs burst their pots. A good top-dressing in early autumn is all that they ask for. One of my most pitiful garden experiences is connected with Nerines, of which I happened to have a good store of finest species. They were left during my absence from home in a vinery at rest in which were some broken panes of glass. The pots were first soaked with rain-then came a severe frost and then bulbs were hard frozen-treatment from which they never recovered, and the whole batch was lost.

This is mentioned as a warning that where Nerines are grown-and they are worth growing-suitable winter quarters, safe from frost, must be found for them, but a window in a warm room will answer perfectly, as it also does for the better known Scarborough Lily (Vallota purpurea). Belladonna Lilies, on the other hand, will so rarely flower in pots that they cannot be recommended for the smaller sort of unheated greenhouse, but planted out in rather poor gravelly soil, they are admirable for the narrow borders close to the wall which are found in some conservatories and corridors.

For such positions also-though it also flowers very well in pots-the handsome Crinum Moorei is very suitable, especially when associated with such plants as Funkia Sieboldi and F. grandiflora (good both in foliage and flower) which will serve to hide the somewhat ungainly length of stem of the Crinum. A note should also be made of another Funkia recently introduced-F. lancifolia tardiflora-which on account of its late flowering should prove valuable under glass.

Kniphofias-the Red-hot Pokers of our gardens-may not seem exactly suitable to rank as pot plants, yet there are some species which do well and are extremely useful grown in this way for autumn flowering. The very dwarf K. Macowani and the more robust K. corallina are kinds in point. For these a cold frame with sunny exposure is the most suitable position in order that the flower stapes may attain their full rich colour.

The new taller growing species, K. longicollis, though hardy, produces its clear yellow flowers too late to open well out of doors, but succeeds admirably planted out under glass, where there is space for it. It would be worth trying, when it becomes better known, grown in a pail or tub for smaller structures where only pot plants can be accommodated, as it flowers naturally from late autumn onwards into winter.

The new Anoiganthus breviflorus, which opens its umbel of golden-yellow flowers in December, may also find a place in the greenhouse with temporary warming power. But enough of these interesting and highly decorative plants have been suggested to bear out the statement that with bulbs and tubers alone-though the half has not been told-we may find material enough to make the cool greenhouse a source of interest from year's end to year's end.

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