Bulbs that may be grown indoors permanently are mostly not winter-hardy outdoors in the colder parts of the country. They fall into two distinct groups: the first consists of freesias, lachenalias, tuberous begonias, caladiums, gloxinias, and all others that have annual roots only; and the second includes all perennial-rooted kinds such as amaryllises (Hippeastrum), agapanthuses, crinums, haemanthuses, and nerines.
Bulbs with annual roots
Annual-rooted bulbs die down completely at the beginning of their resting season and are without tops or roots while dormant. They must then be kept quite dry. They may be stored during dormancy undisturbed in the pots of soil in which they grew. Or, they may be taken out, cleaned, and kept until the beginning of the next growing season in open-topped paper bags, shallow trays, or even suspended in old nylon stockings, in a dry, airy place where they are protected from direct sunshine and widely fluctuating temperatures.
Because, when the end of the resting season comes, bulbs left in pots of soil may start into growth unnoticed, it is usually wiser to remove them from their pots as soon as their foliage has died and to store them without soil where they may be inspected at intervals. In any case they must be replanted in clean, well-drained containers of new soil at the beginning of each growing season.
The water requirements of these bulbs follow a seasonal rhythm. Immediately after planting they are well watered, but additional moisture is supplied sparingly for a few weeks afterward—though with increasing generosity as roots develop.
When the pots are well filled with roots the soil is kept constantly moist and this condition is maintained until, after flowering, yellowing of the foliage indicates unmistakably the approach of the resting season. When that occurs, intervals between waterings are gradually lengthened and finally, when the foliage has completely died, water is withheld and another season of dormancy begins.
No one time of the year is right for replanting all the various annual-rooted bulbs. Many, notably kinds that are native to South Africa, begin their growth cycle in fall and are repotted then. These rest in summer. Others such as gloxinia-g, fancy-leaved caladiums, and some oxalises are dormant in winter and start into growth in spring, at which time they must be provided with new soil and with moisture.
Bulbs with perennial roots
The pot culture of bulbs that have perennial ( permanent) roots differs markedly from those that have annual roots. They are not replanted each year. Often they live for many years in the same container with nothing more than a top-dressing applied at the beginning of each growing season.
Top-dressing means that as much of the surface soil as can be loosened with a pointed stick without damaging the roots is taken off and is replaced with rich earth containing fertilizer. Just before this is done, the plant is removed from its pot and its roots are carefully examined to make sure that the drainage is not clogged and to check whether repotting is necessary. This latter operation ( except in the case of young bulbs that are being grown on rapidly and that are repotted every year or two) receives attention infrequently. Intervals of four or five years between pottings are common . .. and large specimens of clivias, agapanthuses, and some other kinds are not disturbed as often as that.
Most perennial-rooted bulbs have a dormant season during which their tops die down completely. A few, such as clivias, agapanthuses, eucharises, and certain crinums, are evergreen. The evergreen ones obviously require moisture at all times, but much less when they are semi dormant ( even bulbs that do not go completely dormant have a season of partial rest) than when they are actively growing. Bulbs with evergreen foliage must never be allowed to dry completely.
The leaf-losing kinds that have perennial roots, such as amaryllises, nerines, haemanthuses, and eucomises, are kept almost completely dry during their season of dormancy, although the soil is not permitted to become so devoid of moisture that the roots shrivel. Under good storage conditions ( as when the pots are turned on their sides under a greenhouse bench or in a not too hot and dry cellar) there is usually sufficient moisture in the atmosphere to prevent excessive drying, but in a very dry atmosphere there is danger of desiccation and it may be desirable to soak the soil about once a month during the storage period.
Repotting bulbs that have perennial roots
Repotting perennial-rooted bulbs is a simple operation. It is done at the beginning of the growing season. Twenty-four hours before repotting immerse the pot containing the bulbs in water for five to ten minutes and then let it drain.
Prepare the potting soil. Because this will not be renewed for several years it should be fertile and of coarse texture so that it will not pack tightly as a result of repeated watering and thus prevent the free passage of air. A rich loam is the best basis for such a soil.
Grass sod taken from a fertile field and piled in a stack until its roots are dead but are still clearly visible as fibrous material is ideal. If this is unavailable rich garden topsoil from well-cultivated ground is a satisfactory substitute.
Add to the soil an equal bulk of coarse leafmold, compost, or peatmoss; half as much coarse sand; and half as much gritty material of a rougher character such as coal cinders ( but not fine ashes ), old broken brick, or crushed oyster shells. This gritty material should pass through a half-inch mesh and should be free of fine dust. For each bushel of ingredients add one quart of dried cow manure, one pint of coarse bone meal, and one pint of unleached wood ashes. Mix the whole thoroughly while it is in a just-moist but not wet condition and you will have a potting compost in which any permanent bulb will thrive. The moisture content of the mixture at mixing time is important. If it is dusty dry sprinkle a little water into successive layers as you turn it over; if it muddies your fingers spread it out and let it dry before mixing.
Begin the repotting operation by removing the plant from its pot. Next carefully pick out the old crocks ( drainage material) from among the roots at the bottom of the root ball. If the plant is in need of dividing attend to this now. If not, pick away from the top of the root ball as much earth as you can remove with a pointed stick without damaging the roots. If you can pick any soil from the sides of the ball without harming the roots do so. The new soil will adhere more intimately to the root ball and new roots will develop faster if the sides of the ball are somewhat rough rather than smooth at potting time.
The pot into which the bulb is set should be clean and dry, but if it is a new one immerse it in water until bubbles cease to come from it; then let it dry. If you do not do this you may have difficulty removing the plant from its pot at some future time because moist soil sticks to kiln-dry pots.
Adequate drainage is important. Place an inch of crocks over the drainage hole in the bottom of a five-inch pot, proportionately more in containers of larger diameter. Cover this drainage with coarse leaves, moss, or hay to prevent the soil from washing down; then throw in a little soil and make it firm. Now set the plant to be potted in position. It should be centred and at such a level that when potting is completed its old root ball will be covered with a quarter-to a half-inch of new soil and the new soil surface will be sufficiently below the rim of the pot to allow for watering. This means about three quarters of an inch below in the case of a five-inch pot, more for those of larger sizes.
The new pot will ordinarily be about an inch larger all around than the old container. Only in the case of very large specimens should it be as much as two inches bigger all around. If the roots are few and in poor condition it may be desirable to pot the plant into a receptacle of the same size as the one from . which it was taken or even into a smaller one. This is called "reducing." If reducing is necessary, remove all dead roots and as much of the old soil as you can conveniently pick away and then transfer the plant to a container just large enough to hold the roots that remain, with a little space allowed all around for new soil.
Whether the plant is reduced or promoted, the next move is to fill the space between the root ball and the new pot with prepared soil and to ram it with a lath or shaped potting stick. A good potting stick may be made by shaving down the lower eight inches of a foot-long piece of broom handle so that it has two flattened sides and is about three quarters of an inch thick along the shaved-down portion; the rounded upper end serves as a handle.
Ram the soil firmly but not really hard; it should be packed so firm that even by exerting pressure it is not possible to indent its surface noticeably with the finger. Finish the potting by making the surface level and roughening it slightly so that no potting stick or finger marks show.
It is usually well to delay watering for twenty-four or forty-eight hours and then to soak the newly potted plant thoroughly with a fine spray. If the bulb has foliage at potting time, keep it out of direct sunlight for two or three weeks afterward and spray the foliage daily with water. Avoid watering more often than is necessary to keep the soil just moist until roots have taken possession of the new soil. Give no fertilizer until the plant has filled its new pot with healthy roots.
Repotting bulbs that have annual roots
Some annual-rooted bulbs such as tuberous begonias and gloxinias are potted singly, while others including freesias, oxalises, achimenes, and lachenalias are planted several together.
Most annual-rooted bulbs that are normally planted several to a container are set in their final pots at planting time; they are not transferred to larger receptacles during their growing season. For these bulbs a nutritious soil must be supplied from the beginning. Annual-rooted bulbs of kinds planted singly are most often started in small pots and are repotted into larger ones as growth proceeds. These may be started in such a medium as peatmoss and be transferred to progressively richer soils at each potting.
The treatment of freesias well illustrates the procedure adopted with most annual-rooted bulbs that are planted several together. The treatment of tuberous begonias illustrates the method of handling annual-rooted bulbs that are potted singly.
For freesias a soil consisting of mellow loam ( topsoil), coarse sand, and leaf-mould or humus mixed in such proportions that the result is porous and rather sandy and will pass water readily is best. It should not contain so much organic matter that it is likely to remain wet and spongy. Bone meal added at the rate of a pint to each bushel of the mixture is advisable. The pots or pans are drained by placing an inch of crocks in the bottom of each and covering these with a layer of rough leaves or moss to keep the soil from washing down. An inch of dried cow manure may be placed on top of the drainage with advantage. The freesia bulbs should be set with their tops half an inch below soil level, and half an inch of space should be left between the soil surface and the rim of the pot to allow for watering.
The planting procedure consists of filling soil into the container, firming it with the fingers, and levelling it at a suitable distance below the rim. The bulbs are then spaced on this at appropriate distances and are covered to the required depth with soil packed with the fingers.
After planting, the soil is soaked with a fine spray of water and the pots are placed in a cool and light, but not sunny, place. The soil must never be permitted to dry but great care must be taken not to sour it and spoil its texture by overwatering, which is easily done until roots have ramified through it. One excellent method of avoiding the necessity for frequent watering is to cover the newly planted pots with an inch or two of moss and to keep this in position until new shoots push through.
Tuberous begonia bulbs are best started by planting them fairly closely together just below surface level in a pan or shallow box containing a loose mixture of peatmoss and sand or leafmold and sand. This should be kept moist but not saturated. In a temperature of sixty-five to seventy-five degrees roots soon begin to grow. When a good mass of these one to two inches long have developed, each bulb is potted into a well-drained pot just large enough to hold it comfortably with a reasonable space around it for new soil; this usually means a container four or five inches in diameter.
The soil used at this potting should be rich in organic matter, loose, and spongy, one tenth to one eighth of its bulk consisting of dried cow manure, the rest of loam, peatmoss or leafmold, and sand. A pint of bone meal to each bushel should be added, as well as a good sprinkling of chopped charcoal. The latter is of great aid in preventing soil that contains a good deal of organic matter from becoming sour under the influence of repeated watering.
The soil should be packed only moderately firmly and immediately after potting it should be watered thoroughly with a fine spray. A warm and humid atmosphere favors rapid establishment of the newly potted plant. As soon as the roots begin to mat around the outside of this first pot, transfer the plant to one an inch larger all around ( that is, to one that measures two inches more in diameter).
This may be the "final" pot or it may be desirable to repot it once again into a still larger container, but under no circumstances should potting be done so late in the season that there is no opportunity for roots to fill the pot before the end of the growing season. Use a soil similar to that used for the earlier potting but of coarser grade. Do not sift it through a fine sieve. Take great care not to disturb the roots when repotting during the active growing season.
Keep the newly potted specimens shaded and out of moving air currents until they "get over the shift," as gardeners say. Care in watering is especially necessary after each repotting until the new soil is permeated with roots, but extreme dryness must, of course, be avoided.
Feeding potted bulbs
Like all pot-grown plants bulbs respond to intelligent fertilization. In general the particular fertilizer used is less important than how and when it is applied. The most satisfactory types to mix with soil in which bulbs are to be planted are slow-acting organics such as bone meal, cottonseed meal, hoof-and-horn dust, and tankage. Unleached wood ashes are also good. But for supplementary feedings that are applied to plants already potted, more readily soluble, quicker-acting fertilizers are preferred. There is little to be gained from sprinkling bone meal, for instance, on the surface soil of a potted bulb!
There are on the market many highly soluble complete fertilizers compounded especially for house plants. Any of these is suitable for feeding bulbs; so too is a liquid made by steeping a burlap sack of cow manure or chicken manure in water for a week or ten days and then diluting the resultant liquid until it is only faintly odorous and is not darker in colour than weak tea.
Important points to bear in mind are to use supplementary fertilizers in liquid form, to use them often during the season when the plants will benefit from them, and to use them weaker than generally recommended for pot plants. You will not go far wrong if you apply complete commercial fertilizers twice as often and twice as dilute as the manufacturers recommend.
Healthy, well-rooted, vigorous bulbs in pots will benefit from feeding twice a week during their active growing season.
There are a few other points to observe. Never apply fertilizer to a plant that has not filled its container with healthy roots. Never fertilize a bulb that is going to rest. Never fertilize a bulb that is decidedly dry. In the latter case soak the soil with water first and two or three hours afterward with the fertilizer solution.
Permanent bulbs for house and greenhouse
One of the best-known permanent bulbs for indoor culture is the amaryllis (or Hippeastrum, to give its correct botanical name). Gorgeous hybrid kinds have been derived from species that occur wild in the warmer parts of South America. They are massive in appearance, and well-grown examples will each year produce one or more stout, erect stalks each having up to four, and occasionally more, huge crimson, orange-red, red and white, pink, pink and white, or pure white flaring trumpets which remain attractive for a considerable period. A fine amaryllis, well grown, is decidedly a conversation piece.
Amaryllises are displayed to best advantage when placed so that their flowers are seen at about eye level. They are splendid for arranging in groups. Because their foliage is often sparse at flowering time (late winter and spring ) it is helpful if ferns, asparaguses, or other light foliage plants are available for placing among them.
Much less conspicuous than amaryllises, and needing a cooler temperature, is another winter-bloomer, the South African veltheimia, which has a flower head that suggests the hardy poker plant but is of softer hue, while the plant itself is much less gross. Dusty pink perhaps best describes its flower colour. It is charming in a sunny window.
Callas are better adapted to greenhouse cultivation than to growing as house plants, but the white and pink ones may be brought to bloom in a cool sun-room. The yellows are more difficult. Callas are chiefly winter- and spring-bloomers. They last well when transferred from the greenhouse to a sunny position in the home if the location is not too warm and dry. Only when their pots are set at floor level can the taller kinds be enjoyed at their best, but the baby calla, with white flowers, and the pink calla ( the "pink" usually leans strongly to lavender) are short enough to be used at ordinary window height.
Early spring brings clivias in bloom. These are tricky to flower out of a greenhouse but it can be done, and it is certainly worth every effort to persuade these handsome South Africans to develop and expand their lovely heads of orange-yellow flowers, each head fully as large as that of a rhododendron. Clivias should be exhibited near a low window or in a sunroom placed slightly, if at all, above the floor.
In five- or six-inch pots—and highly creditable examples can be grown in such containers—tuberous begonias are desirable house plants for summer display, but, alas, they are not suitable for regions where scorching summers prevail. Even where nights are fairly cool they will probably respond best if you keep them on a cool, lightly shaded porch for most of the summer and bring them indoors on special occasions only. Perhaps you can grow sufficient begonias to permit a rotation system that gives each individual a couple of weeks' tour of duty in the house followed by a recuperation period of two to four weeks on the porch.
The flowers of tuberous begonias exhibit astonishing variation in colour, form, and size. Even the poorest are lovely, but for indoor display—where each plant is scrutinized individually—select the finest. Bulbs are not usually sold in named varieties—the dealer ordinarily labels them according to general flower form and approximate colour. Not until they bloom can you decide which are choicest—cherish the good ones and give them special care so that you may be sure to have them in succeeding years.
Fancy-leaved caladiums are among the most satisfactory plants to grow as summer decorations. They are easy to handle; they remain attractive over a long period; they are available in many distinct and beautiful varieties; and they may be used in containers of widely varying sizes, the bulbs being planted singly if the receptacle is five or six inches in diameter, two or more together if it is larger. For the best effect fancy-leaved caladiums should be grown in pans rather than in deep pots, those the florist calls "azalea pans" being eminently suitable.
The jack-in-the-pulpit-like blooms of caladiums are interesting but last briefly and are more or less hidden by the foliage. These plants are admired for their gorgeous leaves rather than for their flowers.
No consideration of summer-flowering bulbs suitable for cultivation in pots would be acceptable without mention of gloxinias. These are plants for the greenhouse, for choice positions in the home, and, in summertime, for locating on shaded, sheltered porches. Their foliage must be protected from getting wet. Their velvety trumpet flowers come in a rich array of colors and in white. They are displayed to perfect advantage above large, softly furry, dark green simple leaves. Gloxinias are choice flowers; there is an unmistakable air of quality about them.
Less well known than gloxinias and generally of more restricted usefulness, although not less beautiful, are some of their botanical relatives. Here belong achimenes, which have pretty flowers of lavender, purple-blue, white, red, and pink . . . flowers that somehow seem to remind one of pansies although they do not really look like them except for the fact that their faces are flat. Isolomas, or kohlerias, are kin of gloxinias. They are hairy plants with leafy stems two to three feet tall and have drooping, tubular, spotted-reddish flowers that possess considerable charm.
Corytholoma and Smithiantha are the botanical names of other gloxinia relatives that older gardeners knew as gesnerias. These are plants for the advanced amateur rather than for the beginner; they really need a greenhouse for their successful culture. If you are adventurous and can provide the conditions they need by all means try them. Corytholoma cardinalis has bright green leaves and brilliant scarlet flowers in fall and early winter—just the right colors for Christmas and it can be bloomed then in the greenhouse! Well-known specimens are a welcome change from better-known "Christmas plants." Smithiantha zebrina and. Smithiantha cinnabarina are summer-bloomers having large, richly coloured, hairy leaves and handsome flowers.
The number of vines that grow from bulbs is limited and so we especially appreciate the glory-lily ( Gloriosa) which can be trained to enframe a window, to clothe a trellis, or to attach itself to other suitable supports. Over a long summer season it delights us with its elegant, lively red and yellow flowers that are as useful for cutting as they are decorative on the vine.
A close relative of Gloriosa that will interest
the plant lover even though it is not as showy is the yellow-flowered
Littonia modesta. There is, by the way, also a beautiful buff-yellow-flowered
variety of gloriosa that is rare and is well worth seeking; it is called
Among bulbs that bloom in winter and spring are a group of South African natives that need decidedly cool conditions and the full exposure to sunshine. They are plants for the greenhouse or, if conditions are very favourable, for the slightly heated sun porch; they cannot be expected to thrive in living rooms.
Here belong fragrant freesias, that nowadays may be had in such a wonderful color range, and the closely allied baboon flowers ( babianas ) with cupped flowers in tones of lilac, violet, red, and yellow. Sparaxises, slender graceful ixias—which range in hue from near-white through yellow and orange to red and purple and, in the case of lxia viridiflora, include a wonderful metallic green that reminds one of a colour in a peacock's tail feather—tritonias, lachenalias, lapeirousias, gladiolus-like watsonias, and montbretia-like chasmanthes belong here. So do "baby" gladioluses and gladiolus species ( unimproved kinds from the wild), the best known of which is fragrant Gladiolus tristis which has tall spikes of soft-yellow flowers.
South Africans for spring bloom that are easier to grow in the home than some of those mentioned above are several oxalises, the most frequently seen of which are the clear-yellow-flowered one popularly called Bermuda buttercup (Oxalis cernua) and the pink, lavender, and white varieties of Oxalis variabilis that form the "Grand Duchess" series. These must have full sun and fairly cool conditions. They are excellent window garden plants.
This by no means exhausts the list of bulbs that may be successfully cultivated in pots in the greenhouse and home. If you crave greater variety, try Ornithogalum arabicum, which has tall stems topped by clusters of black-centred white flowers that smell richly of ripening apples . . . or the South African chincherinchee, the cut blooms of which last so long that shipments are made from its home country to the United States and the flowers remain attractive for weeks after arrival.
The white-flowered flowering onion called Allium neapolitanum is dainty and easy to grow. If you can provide tropical greenhouse conditions by all means cultivate the Eucharis lily—it will reward you with two or three crops of sweetly fragrant, excellently formed pristine flowers each year.
Seek out, too, some of the bulbs belonging in the genera Vallota, Sprekelia, Leucocoryne, Acidanthera, Haemanthus, Hymenocallis, Hedychium, Habranthus, Crinum, Brunsvigia, Chlidanthus, Scilla, Arum, Alstro emeria, Dierama, and Crinodonna ( Amarcrinum) . If your taste runs to oddities you will find them among Amorphophallus, Hydrosme, Schizobasopsis, Sauromatum, and Urginea. Among bulbous plants can be found kinds to satisfy all tastes.