If the greenhouse, however, happens to be unheated a professional gardener will probably shake his head in despair of doing himself any credit during the winter months, and, beyond supplying a few evergreens in pots, may even decline altogether to attempt any floral decoration until the spring. It is not to be denied that there are considerable obstacles in the way, and for the winter almost everything depends upon the time available for preparation; but a good deal may be done, at the cost of a few shillings and a little time and trouble, with annuals and biennials or certain other plants, possessing, strictly speaking, a longer term of life, but which may be treated as such.
A few suggestive hints as to the most suitable may be useful, not only to those who mean to depend entirely upon such yearlings, but for others, who will find many of them exceedingly valuable, if not indispensable, additions to their flowering plants. Where time fails to raise these for ourselves it is generally possible to buy strong seedlings of ordinary sorts ready for potting, so that we need not wholly despair of procuring decorative material of this temporary nature, and with little outlay.
Annuals are often regarded with some contempt, but it may be traced in most cases to failure in growing them well, resulting mainly from the initial mistake of sowing the seed too thickly. Seed is often minute, marvellously so when one thinks of the germ of life and the earliest food for that germ which is, in one way or another, packed up in it. It does not at all follow, however, that the plant produced from a microscopic seed should require to be looked at through a magnifying glass when full-grown, and this we must always take into account. A single seedling of Nemophila or Limnanth es will make a grand free-flowering specimen if allowed proper scope, when a dozen cramped into the same space will be utterly worthless and disappointing.
Seeds, minute or otherwise, must not be sown too thickly, and with the larger kinds, like Tropxolum or Lupine, it is a good plan for indoor work to put them singly into the smallest pots and to shift them as required into larger sizes. Annuals, again, under these circumstances must never in the earlier stages be allowed to get pot-bound, needing constant attention from the first, until they get their final transfer into the flowering-pot.
Hardy biennials may often, on the contrary, be planted outside with advantage to make their growth before being potted for the greenhouse, which is a great saving of time and labour. These require a somewhat longer time to bring them to the flowering stage, and are generally sown one year to flower the next. The time of their flowering depends in most cases on the time of sowing and subsequent culture-a statement not so obvious as it may seem at first sight, because they are sometimes contrary in their ways, and may, if they are in sulky mood, pass over a whole season.
A houseful of Wallflowers in midwinter, some in flower and some coming on, would be no mean success to attain. The full red-brown of Harbinger and the clear yellow of Belvoir Castle, which are amongst the earliest to bloom, are at all times beautiful, and other later well-known varieties, to be found in every seed list, will give intermediate shades never out of harmony with each other. Wallflowers are really perennial in duration, though not very long-lived, but as they flower within a few months of sowing, they are commonly treated as annuals.
For very early winter the first sowing is best made in April, and a second may follow three weeks later. Where there is a bit of garden ground the young plants may be pricked out 3 in. apart in rows with not less than 6 in. between the rows. Later on, when they begin to require more room, every second plant may be transferred to a new row, allowing 6 in. between each of them. Here they may remain until October, when they can be potted in 5-in. pots for flowering in the greenhouse.
Where there is no garden, boxes or zinc trays may be made to serve the purpose. In either case care must be taken to keep the plants weeded and watered in dry weather. Wallflowers are hardy things-never more so than when grown on the scanty foot-hold of a crumbling wall, their natural home.
Cultivation in rich soil tends to make them less hardy, and the shelter of glass, therefore, is very welcome in severe and especially in windy weather, and will also hasten the flowering time. Double German Wallflowers are very popular and handsome with their quaint purple and Primrose tints, but they are more tender and not so fragrant as the smaller-flowered common sort. They come into flower later, and the seed need not be sown till May.
Stocks, which are mostly biennials, are neither so hardy nor so early as Wallflowers, but they are very useful, and if seed of the intermediate section be sown in June and treated much in the same way as recommended for Wallflowers they will flower quite early enough to take their place when the Wallflowers begin to grow shabby.
Some experts prefer to grow them entirely in pots, giving them shifts into larger sizes as soon as the roots touch the sides. All-the-Year-Round is a very fine white variety, and there are crimson and purple shades in the same strain. For a later display the annual Ten-Week Stocks may be sown as early as February under glass, and, with good cultivation, will be in fine flower long before any of their kind out of doors. The large, sweet-scented flowers of this section are very beautiful in the infinite variety of their delicate tints.
Scarcely any introduction of recent years has been more welcomed than that of the annual Margherita Carnations of Italian origin. Sown early under glass, planted outside as soon as the seedlings are strong enough, and allowed room enough to develop, they will grow during the summer into vigorous plants well set with buds in time to be potted with other things for winter flowering.
If the season be favourable many buds will open before Christmas, and with a good strain of seed, which is always a most important factor in the case, a very large percentage of the plants will give fine double-fringed flowers of refined hues. The single " rogues " are also extremely pretty, and by no means to be despised as decorative plants.
Few people realise how well the common white Pink, as well as its rose-coloured form, treated practically as biennials, respond to gentle forwarding under glass. Tufts of cuttings or divisions of old plants put out in new soil in rows in May can be lifted and potted in September. They may then stand out of doors with the pots plunged in ashes until Christmas or thereabouts, and will come into flower about nine weeks after being brought in. How welcome they are, filling the greenhouse with sweetness on an April day, none can tell but those who have tried them.
Sweet Peas are a great stand-by, but it is essential that they should be sown about midsummer to come in for very early blooming. Three seeds sown in a small pot, and transferred with as little disturbance of the roots as possible into larger sizes, and grown out of doors, will make beautiful specimen plants.
They may be pinched back now and then to make them bushy, and will flower well in a o-in. pot ; but they should be brought under shelter before the first early frosts at the end of September or they may receive a check which will retard their blooming. Eckford's good varieties offer abundant choice of colour, and these should be kept distinct, as mixtures are seldom desirable or effective.
Any of the hardy annuals which are recommended in the seed lists for autumn sowing, which usually means August and onwards, may be tried with a fair chance of success, and should flower by relays from early spring. Mignonette will scarcely be overlooked. The old-fashioned kind, though not so large or handsome as Machet, Parson's White, and some of the Covent Garden strains, is the sweetest of all.
Three seeds sown in a small pot, the strongest only to be retained, and re-potted as required in rich soil, will give very satisfactory results.
Tender annuals for summer and autumn blooming, such as Astors, Tropolums, Mimulus, Nemesia strumosa, Salpiglossis, Celosias, Martynia fragrans, &c., must be sown under glass in March, April, or May, according to circumstances, and require a good deal of care in pricking-out, potting, and in some cases pinching-back, with as much open air as possible to prevent their spindling.
These may be so timed as to flower until late autumn. Greenery should not be forgotten, for which the Japanese Hop, Zea Mays, and some of the elegant annual grasses, will answer well. The biennial Fish-bone Thistles (Chamepuce Casabonm and C. diacantha) are also very useful for this purpose. Cosmos bipinnatus, with its finely cut leafage, makes an effective foliage plant while it is young, and a few out of a batch of seedlings might be reserved for this purpose, but the plants intended to flower will do better if summered out of doors.
This, being one of the latest of autumn-blooming annuals, is not very satisfactory in the garden for our climate, but if grown under generous conditions it is exceedingly ornamental in the greenhouse during October and November, either in its white or light purple form.
I will transcribe a short extract from a book seldom to be met with in the present day--Mrs. Loudon's work on annuals, which is well illustrated with coloured plates.
The hints there given have been very useful to myself, and they form a guide for the general culture of annuals in pots, whether autumn or spring sown. I quote the following passage verbatim, but it will be noticed that in the case of Rodanthe Manglesi, the plant in question, the time of sowing is stated to be April, Rodanthe being half-hardy, but the same cultural directions are applicable whether the seed be sown in autumn or in spring, i.e., whether the annuals be hardy or half-hardy.
The seed was sown on April 5, in pots filled with three parts peat, or rather heath-mould, and one of loam. In the first week of May, when the plants were still in the seed-leaf, they were pricked out singly into small 2 1/2-in. or 3-in. pots. In a week's time they were shifted into rather larger pots, and this shifting was repeated six times, always into rather larger pots, till the middle of August, when the plants were in 94-in. pots, and when they were first allowed to flower.
On September 14, when one of these plants was sent to us by Captain Mangles, it was 1 1/2 ft. high about 4 ft. in circumference, and had a thousand expanded flowers upon it, besides innumerable buds, which have continued expanding ever since, and it is still (November ) a blaze of beauty. It is watered every morning with a little warm water, and the dead flowers are cut off as they fade. The great art,' says Mr. Goode, in the manuscript directions sent us by Captain Mangles, is to prevent the plant from growing upwards, and to cause it to increase and expand in breadth instead of length.'
To do this, all that is required is to watch it well, and the moment the roots have nearly filled the pot, to transplant it into a larger one. By constantly attending to this, the plants will grow thick and shrubby in their character, and while the shoots will grow strong and capable of bearing a most profuse floration, the beauty of the plants in shape will be greatly improved."
This may be old-fashioned practice, but nevertheless the above passage is highly suggestive, and it proves that an annual plant may be grown into a fine specimen, even though it may live out its life in a succession of pots. The same routine of treatment will answer equally well for biennials.
One or two dwarf annuals of a succulent character are well adapted for summer flowering under glass-Portulacas, which enjoy the extra heat and are delightfully gay in their vivid colouring of crimson, yellow, and purple, and the free-flowering Mesembryanthemum tricolor, pink and white, with a dark eye. These should all be sown very sparingly, as they are apt to resent transplanting, and do better if they are thinned rather than pricked out, looking best when grown in shallow troughs or pans.
The different varieties-orange, yellow, and white-of Iceland Poppy (P. nudicaule) do well treated as biennials, and, sown in autumn, make charming pot plants for early spring.
For those who like to travel out of the common track, two beautiful species of Pentstemon, not very often met with, may be added to the biennial list. P. Cobwa is a Texan plant which blooms naturally late in autumn and has long, shining, deep green leaves and spikes of bell-shaped lilac or white flowers.
Being very viscid they attract insects to such a degree out of doors that their beauty is sometimes marred by the small victims which cannot get free from the sticky trap, but they make very fine pot plants. P. Murrayanus is quite distinct from the last, having glaucous leaves and bright scarlet tubular flowers, and there are garden varieties distinguished, as Grandiflora, of different shades of rose and violet.
Both these species, which are quite different to the well-known border Pentstemons, do better sown in early autumn and protected during the winter either in a cold frame or greenhouse, as they are somewhat tender, but are well worth growing by those who do not begrudge time and trouble.
As a garden experiment, which probably has never been attempted, it would be interesting to prove what could be done in the way of cold greenhouse decoration by the use of annuals and biennials alone. To this end I will gather the hints given above into four distinct rules :
The successful cultivation of annuals is, in fact, a fine art, and may be summed up in the garden-lad's definition of gardening, " A-doing of things at the right time "-a maxim instilled into his understanding, no doubt, by a past-master of the craft, and which applies with double force in the case of this handsome but short-lived section of plants.