Because results are achieved with considerable certainty and relative quickness, planting bulbs and bringing them into early bloom indoors is a highly interesting and distinctly educational activity for children. If you have youngsters purchase a few bulbs for them each fall and let them get their fingers in the soil and become acquainted with the joys of indoor gardening.
Bulbs suitable for forcing are nearly all of kinds that are hardy outdoors, although a few such as the narcissuses "Paper White," "Grand Soleil d'Or," and "Chinese Sacred Lily," Roman hyacinths, and Easter lilies are not reliably so in the North. After they are through blooming forced bulbs are of no further value as pot plants. They will not force satisfactorily a second year, but in many cases they can be salvaged for use in the outdoor garden.
Although fashions in indoor plants change, it seems certain that forced bulbs will always be popular. They appeal because the period between planting and flowering is short and because their blooms make gay displays when flowers are especially welcome. Some such as hyacinths, lilies, and certain narcissuses are wonderfully fragrant. Chances of failure are slight if a few simple rules are followed.
Because individual pots of forced bulbs do not remain in bloom long—usually for not more than ten days to three weeks—they must be brought into flower in planned succession to ensure continuous bloom.
The planning that precedes bulb forcing should be based not only upon the desire for a progression of bloom through winter and spring but also upon a consideration of the places in the home where pots of bulbs may be used effectively. Thought must be given, too, to locations where they are to be grown until they come into bloom. Nearly all need to be kept for some weeks after planting in a dark, cool place.
Unless good root growth is made under such conditions before they are placed in forcing temperatures they will not flower satisfactorily. "Cool," for this purpose, means a temperature above freezing but not greatly exceeding forty-five degrees. The conditions we attempt to approximate are those to which bulbs planted a few inches deep out-of-doors are subjected; this means darkness, even moisture, and fairly low, reasonably stable temperatures.
One satisfactory way of assuring such conditions is to bury the pots, after planting, outdoors under an eight-inch covering of fine ashes, sand, or peat-moss. A variation is to place the potted bulbs in a large ventilated box or bin arranged in such fashion that at least six inches of peatmoss is between the sides of the box and the pots and so that eight inches of peatmoss covers them. The box should be located in a shaded place outdoors. If burying in ashes, sand, or peatmoss is not practicable, the pots of newly planted bulbs may be kept during their rooting period in darkness in a box or closet in a cool frost-proof cellar, sun porch, attic, or similar location.
Usually six to ten weeks of this treatment
will be needed before the bulbs are ready to be brought into the light
and greater warmth. Transfer the bulbs from darkness before shoot growth
is three inches tall but not before healthy white roots crowd the pots.
Lack of sufficient light and too high temperatures are responsible for many failures with forcing bulbs. A night temperature of fifty to fifty-five degrees with a daytime rise of five to ten degrees is ideal for most kinds. This is not always easy to provide in a dwelling house but even in a warmer room you may find that temperatures within this desired range prevail close to a window that has no radiator beneath it. Keep a thermometer near your developing bulbs so that you know to what temperatures they are subjected.
After the bulbs are brought into light plenty of moisture is needed. The rooting medium must never be allowed to dry. It is difficult to give too much water to well-rooted bulbs planted in well-drained containers with holes at the bottom but it is easily possible to overwater those planted in vermiculite, peatmoss, or other soil substitutes in undrained receptacles. Endeavour to keep such materials evenly moist but not constantly saturated. In the case of bulbs planted in pebbles and water, or in plain water in special hyacinth glasses, keep the water level about even with the bases of the bulbs.
Bulbs that have been forced are of no further value for indoor cultivation but if kept watered and growing under sunny conditions until their foliage dies down naturally they may be removed from the soil and be planted in the outdoor garden as soon as the weather is warm enough or after a summer of storage in a dry, cool airy place. Almost all will recover and bloom satisfactorily outdoors in future years.
Fall is the time to plant bulbs for forcing. In most cases the best results are obtained when this is done as early as good bulbs are obtainable from dealers. But in a few instances—for example with "Paper White," "Grand Soleil d'Or," and "Chinese Sacred Lily" narcissuses and with hyacinths—several plantings may be spaced at two- or three-week intervals to provide a succession of blooming plants.
Forcing bulbs may be planted in soil, in which case the containers must have holes at the bottom to ensure drainage, or in a sterile rooting medium such as vermiculite or "bulb fibre." Bulb fibre is a mixture of peatmoss, oyster shell chips, and chopped charcoal. These ingredients are mixed in the proportions of about two quarts of each of the latter to a bushel of the former. Bulb fibre or vermiculite should be used for bulbs planted in undrained containers unless they are planted, as some few kinds may be, in pebbles and water or, as hyacinths sometimes are, in plain water to which a few lumps of charcoal have been added. There is no doubt that the best results are assured by growing bulbs in soil in regular clay flowerpots or in the shallow flowerpots that florists call pans.
Because forcing bulbs contain at planting time in undeveloped form all the flowers that they will produce and because they have within themselves much of the food material needed for the development of their leaves and flowers, especially rich soil is not necessary. Nevertheless they should be given earth of good texture and reasonable fertility. Do not expect results if you plant them in a sticky, infertile clay. If possible obtain topsoil—the kind that would grow good vegetables or satisfactory flower-garden plants. Add to it about one third by bulk of peatmoss, leafmold, or compost and, if it tends to be heavy, an equal amount of coarse sand or fine cinders. Mix in bone meal at the rate of one pint to each bushel. Have the soil in a just-moist condition at planting time—not so dry that it is dusty, not so wet that it sticks to the fingers.
Most bulbs are planted several in a container, spaced so that they almost touch each other. With the exception of stem-rooting lilies, which are planted low in their pots and are top-dressed later, set the bulbs so that their tips just show at the soil surface which should be an inch or so below the rim of the pot to allow for watering.
Prepare each pot for planting by placing over the hole in its bottom an inch or so of coarse cinders, bricks broken to the approximate size of marbles, or crocks (pieces of broken flowerpot). Cover this layer with dead leaves, moss, or straw to keep the soil from washing down and clogging the drainage. Fill with soil to a suitable level and press it lightly.
Do not make the soil beneath the bulbs firm or the downward pressure of the developing roots will lift the bulbs right out of their pots. On the other hand, the soil on top of the bulbs ( the surface soil) should be made quite firm by pressing it with the tips of the fingers. This firm-at-the-surface, loose-underneath arrangement minimizes the danger of the bulbs lifting. After potting, water thoroughly and place the pots where they are to stay during their rooting period.
The technique of planting in bulb fibre is somewhat different. Moisten the fibre thoroughly and squeeze out all surplus moisture. Fill the container with fibre and press it down firmly leaving its finished surface almost or quite level with the rim. With the fingers scoop a hole in the surface and plant one bulb. Pack fibre around it and repeat this until the container is filled; then put it in a dark cool place for rooting. Undrained containers must not be put outdoors; they must be kept under cover so that rains will not fill them with water.
If vermiculite is used as a rooting medium,
simply pour it into the container to a suitable level, set the bulbs upon
it, and add more vermiculite until only the upper halves of the bulbs
show. The surface may be level with the rim of the receptacle. Don't press
or pack vermiculite. After planting apply enough water to moisten the
vermiculite but not to make a pool in the bottom of the container.
Only first-quality bulbs are worth buying for forcing. Second grades, which may be usable for outdoor planting, are less likely to be satisfactory indoors.
Top-quality bulbs always give finer flowers, and in some cases, as for example with narcissuses, more flowers per bulb are had from them than from inferior grades.
When selecting bulbs for forcing ( this particularly applies to narcissuses, tulips, and irises) choose varieties that are known to be especially suitable for the purpose; this is particularly important in the case of bulbs that are to be brought into bloom well in advance of their normal outdoor season. For later forcing, to have flowers three or four weeks only before the same varieties flower outdoors, the selection of special forcing varieties is of much less importance. Catalogs of specialists indicate the best forcing varieties.
Containers to use
To achieve the finest decorative effects with bulbs forced indoors it is necessary to consider where in the home they can be displayed to best advantage and to give thought to the types of containers to use. From an aesthetic point of view the best results and the greatest enjoyment may come, not from keeping them in a window, but from moving them when in bloom to places where they may be appreciated more intimately, where they make a more dramatic appeal, or where they fit most pleasingly into the general decorative scheme.
By all means select containers which will not look out of place. Clay pots may be unobtrusive on an enclosed terrace, sitting on a tile-top table, arranged on a plant stand, or standing at floor level, but if bulbs are to be used on dining tables, coffee tables, chairside or bedside tables, more refined containers are usually preferred.
For such locations the best answer may be a glazed jardiniere into which regular clay pots can be set, but jardinieres for this purpose are not easy to find. More often than not they come in shapes that either leave half an inch or more of clay pot protruding above their edge or are too ungainly to be attractive. Why jardinieres are so seldom proportioned to fit the standard clay pots and pans of the florist is something of a puzzle.
For bulbs that are to be grown in containers without holes in the bottoms there are numerous solutions. Glazed receptacles are available in any number of shapes and sizes—varying in price and quality.
For bulbs which do not have to be buried outdoors after planting, such as "Paper White" narcissuses and Roman hyacinths, you may use beautiful handmade bowls in neutral colours. But when the containers must be plunged outdoors, the danger of breakage must be considered and only clay pots or inexpensive glazed containers should be employed. Chinese pewter, antique bronze, and specially constructed boxes of wood masonry or metal with removable liners may also be used.
For special indoor display sizeable built-in boxes are good, pots of bulbs already in bud or flower being set in them in moist peatmoss deeply enough to hide their pots. If the boxes are wide enough, a few carefully selected foliage plants may be used as background and a trailing vine such as English ivy may be employed to soften the front. The influence of changing design on contemporary homes affects the use of plants as it affects furniture trends. Displaying plants attractively indoors is an art that challenges one's creative ability.
Kinds to grow
If we accept November as the beginning of the forcing season, among the earliest bulbs to be had in bloom are three similar narcissuses: the "Paper White" with clusters of white flowers, "Grand Soleil d'Or" with golden-cupped yellow flowers, and the "Chinese Sacred Lily" with flowers that have yellow cups and creamy white petals. All are sweetly scented.
Because their flower stems are eighteen inches to two feet high and their foliage ample and of nearly the same height, they are most suitable for setting on low stands. Select for them containers at least three or four inches deep and broad enough to accommodate five to seven bulbs without touching. Early-planted bulbs of these narcissuses may be had in bloom by Thanksgiving. Successive plantings will provide flowers well into the new year.
Roman hyacinths, often sold as "French Roman hyacinths," may be had in bloom as early as these first narcissuses. They have small bell-shaped flowers in a looser, more graceful arrangement than the large show varieties; they produce several flower spikes from each bulb, but they come in white only. Prepared hyacinths, sometimes called "Dutch Roman hyacinths," are similar and are available in pink and blue as well as white. They cannot be had in bloom quite as early as the French Romans but even so they may be flowered before Christmas.
Bulbs of both the French Romans and of the prepared hyacinths that are intended for early flowering must be planted as soon as they are received for retail sale in August or early September—and good results are possible when bulbs are grown in pebbles or fibre. These are more usable for dinner and luncheon table decoration than are large-flowered hyacinths.
Lily-of-the-valleys are easy to grow. They are not true bulbs, but the single crowns or "pips" from which they grow are treated much like bulbs for forcing purposes and are offered in the catalogue of bulb dealers. The "pips" are available from late fall until early spring. They are suitable for small deep bowls filled with fibre or for growing in soil in regular flowerpots. Straight-sided bowls are better than those with slanted or curved sides because root growth is heavy and the plants stand up stiffly. The pips flower in about four weeks from the time they are planted.
Except for specially prepared (precooled) daffodils and tulips that need very special temperature control from the time they are received and are suitable for greenhouse cultivation only, it is well into the new year before most other forcing bulbs can be had in bloom.
Hyacinths are among the earliest. When grown in flowerpots in soil or in bowls in fibre they have great decorative value. Unlike most bulbs hyacinths look well when grown singly in small pots, and you may find more places in your living rooms appropriate for such examples than for large bowls that display a number of large-flowering spikes. Nevertheless, bowls planted with several bulbs make gorgeous feature pieces when suitably located. Because hyacinth varieties may not bloom together even though given the same treatment, plant only one variety in each container.
Colours include pink, rose, scarlet, yellow, lavender, blue—from light to very dark—purple, and white. Depth of colour will hold better if the bowls are removed from full sun during the brightest part of the day. Because the perfume of hyacinths is heavy they will be more appreciated if there are only a few in the house at a time.
Hyacinths are as easy as "Paper White" narcissuses to grow in water if you use high glasses designed for the purpose. These glasses are about seven inches tall and are pinched in near their tops and flared sufficiently above the pinch to permit setting a bulb in the cup so formed so that the roots that develop from the bulb can extend down into the water. Hyacinths grown in such containers have the. added attraction of visible root development as the plants mature, but are somewhat awkward in appearance. Bulbs grown in clay pots or deep bowls have greater decorative value and usually yield larger flowers.
All varieties of narcissuses and daffodils should be planted several together in pots, pans, or bowls, using one variety to a container. The larger varieties grow from eighteen inches to two feet high and have an abundance of long, decorative leaves. When the bulbs are in flower, the containers are bulky and have considerable weight; they can best be enjoyed below eye level as seen from a sitting position. Low stands or stools are serviceable to set them on, provided they are of the right height.
But if you wish to arrange groups of bulb bowls in front of a window that extends nearly to floor level, a better plan is to acquire a set of blocks either of solid wood or of hollow structure—such as those used for store window display. These blocks can also be used for displaying pots of bulbs against a space of free wall very effectively. Such displays with spot lighting can be very dramatic after dark. Glass bricks or building blocks may be substituted for the wood blocks but are not as satisfactory.
Tulips are a little more difficult to force in the house than hyacinths and narcissuses because they are best grown in a moderate temperature in an airy but moist atmosphere, which is difficult to provide without a cool greenhouse. Because they are more temperamental, selections should definitely be made from among well-proven varieties, which means generally those of the single early and early double types.
Unless tulips are to be displayed considerably below table level indoors, only the shorter-stemmed ones will be easy to use. Some of the tall May-flowering tulips are richest of all in color, however, and should by all means be considered if cool growing conditions can be provided and if they can be displayed to good advantage. Staking will likely be necessary and heavy wire or very thin bamboo stakes should be used for support—the stems being tied with lightweight green thread or narrow pieces of raffia as inconspicuously as possible. Stakes set around the outside of pots with string stretched between pulls the plants together too much and detracts from their natural beauty. Pots should not be planted with less than five or seven tulips; some of the shorter ones look very well in pans.
Among other bulbs suitable for forcing are a number of the smaller-flowered ones that are especially valuable for growing in shallow bowls and in bulb pans, which are like ordinary clay pots but not as deep. Simple, unpretentious containers are in the best taste for these small bulbs.
Crocuses, grape-hyacinths, and certain scillas are the easiest to force. Any of the grape-hyacinths and any of the crocuses make delightful subjects. Of the squills, the species Scilla biflora and Scilla sibirica and the splendid variety "Spring Beauty" are recommended. Snowdrops, winter aconites, and Iris reticulata and its delightful varieties may also be successfully forced although they are inclined to be less dependable.
All these small bulbs and some of the others mentioned here must be allowed to root well under cool conditions before being brought inside, and even after they are indoors they must not be subjected to much warmth. A night temperature of fifty degrees that is not increased to over sixty degrees during the day is ample but may be difficult to provide in the house.
Other standard forcing bulbs are lilies—particularly Easter lilies, which are brought into bloom in such great quantities for the Easter season—and irises of the Wedgwood types, which may be had in bloom from Christmas onward. The latter provide splendid cut flowers. None of these is suitable for growing in the house; they are essentially plants for greenhouse cultivation.