Greenhouse cultivation of Carnations
See also, main Carnation article.
American methods of culture for indoor bloomCH.
The modern method of propagating the carnation for commercial growing is by means of cuttings which are taken from either the blooming stock or from plants that are grown for cuttings alone. The old method of layering (Fig. 809) would prove too slow in increasing stock for present-day needs. Millions of cuttings are rooted each season for planting the houses for blooming purposes. So much depends on the quality of the cutting in keeping up the vitality in the stock that expert growers have learned to discriminate in their selection. The best cuttings, if taken from the blooming stock, are those from near the middle of the flower-stems (Fig. 810). These will not only show greater vitality than those taken higher up or lower, but they will prove more floriferous The tip cuttings are likely to give a flower-bud immediately and, if this is pinched out, develop into a weak plant. Those taken from the base develop a large spreading growth known as "grassy." The cuttings are severed by an outward pull and are afterward trimmed of all surplus foliage before being inserted in the propagating sand. Have a sharp knife with which to trim and a pail of fresh water into which to throw the cuttings as they are trimmed. Make a smooth cut at the base, near the joint, so that the lower pair of leaves will peel off readily, leaving a half-inch of clear stem to go into the sand. Shorten those leaves which turn outward, leaving those which stand fairly upright. The removal of part of the foliage is to avoid crowding in the bench and also to prevent flagging while the cutting is giving off more moisture through its leaves than it is taking up through the stem. The cuttings are inserted in the sand about ¾inch deep in rows across the bench, placing the cuttings about ¾inch apart in the row and the rows about 2½ inches apart, according to the size of the cuttings. Use a putty knife for making the cut in the sand. The sand is kept constantly moist and the cuttings are protected from both the sun and drafts by means of muslin curtains. Frequent spraying should be avoided, though it must be resorted to at times to prevent flagging on warm windy days. The most favorable conditions for propagating are usually secured during the months of December, January, February and early March. During that period, ventilation is limited and a fairly even bottom- heat is easily maintained. Keep a bottom temperature of about 60º, while the overhead temperature should be about 52°. Any bench that can be protected from sun and drafts will prove satisfactory. The bottom of the bench may be of wood or tile, the latter being preferred on account of more perfect drainage and a greater retention of warmth. The sand should be 3 inches deep after being packed down by means of a tool made from a 2-inch plank about 6 inches wide and12 inches long with an inverted V-shaped handle. In about four weeks the cuttings should be ready for potting (Fig. 811). Those that come out of the sand February 15 or earlier should be potted first into 2- inch pots and later on shifted into larger pots as needed. Those potted later may be placed directly into 2½-inch pots and left until planted out, the object being to keep the young plants growing steadily until they are planted in the field. Stunted, pot-bound plants will be slow in breaking and are likely to develop stem-rot in the field. Use a moderately light soil and only fairly rich.
When the young plants begin to run up to flower, they should be topped back to about four joints above the pot (Fig. 812). A low-branched plant will stand up better and will give less trouble in supporting later on. A second topping may be necessary before planting- out time, on early-propagated stock. A slight hardening-off of the young plants before planting out is beneficial, though not essential. This is usually done by placing the plants in cold-frames about two weeks prior to planting them in the field. Late April or early May is the time for planting in the field, according to latitude and climate. A rich loam, inclined to sandiness, produces the finest plants in the shortest time. In a heavy soil the growth will be heavier, but slower and less branching. Set the plants about 8 inches apart in the rows, and if hand-power is to be employed in cultivating, space the rows about 16 inches apart. Space farther if horse-power is to be used.
When a large business is done in young plants or rooted cuttings, a part of the stock is grown especially for cuttings alone. These plants are benched the same as those for blooming, but are not allowed to bloom. As the shoots begin to run up to flower, they are broken off a few joints higher up than is done when topping in the field. The young shoots which result from these breaks are taken off for cuttings, the very finest cuttings being secured in this way. These are trimmed and handled the same as those taken from the flower-stems.
When packing cuttings for shipping, moist sphagnum moss is used in which to pack the roots. Cut papers (newspapers are used mostly) into sheets about 10 by 18 inches. Lay a strip of moss about 3 inches wide across the middle of the paper lengthwise. Then lay the cuttings side by side with only the roots on the moss. When twenty-five have been laid on, begin to roll from one end until all the cuttings have been taken up. Then turn in the lower part of the paper and continue to roll until the end of the paper has been reached and tie around with any kind of cord. There is little difference in the returns from plants grown for cuttings and those grown for blooms, providing a fair market is found for each.
In shipping plants from the field, the soil is all shaken from the roots. The plants are then set upright in the shipping-cases with moist moss between the roots, a layer of damp moss having first been placed on the bottom.
Cultivate as soon as practicable after each rain, and in the absence of rain at least once each week. Shallow cultivating is recommended, just enough to maintain a loose mulch on the surface. Do not water carnations in the field under any consideration. Cultivation will preserve moisture in the soil without causing soft growth. Keep topping back the young shoots as fast as they begin to run up, thus building up a shapely bushy plant.
If plants are to be placed inside during the summer, the benches should be refilled and made ready for planting as soon after May 1 as possible. It will be a great help to get the plants under way on the benches before hot weather sets in. Fill the benches the same as for field-grown plants and set the plants where they are to bloom. Indoor culture is practicable and profitable only when the benches can be spared by early May. If a good market can be found for the May and June cut, they will more than offset the slight advantage derived in the fall from indoor culture.
If the blooming plants have not made an exceedingly rank growth, they may be cut back sharp early in May, cleaned off, mulched with long manure and grown on for blooming the following year. This should not be attempted, however, unless the plants are free from disease or insects and in good condition to break freely from the lower part of the plant.
Carnations are grown successfully on both raised and solid benches. Perfect drainage is essential, and must be provided for, if solid beds are to be used. There will be no difference in the quality or the quantity if both are properly handled. By the end of June the old blooming plants will become exhausted, and refilling the benches to receive the new plants from the field will be in order. Clean out the old soil, whitewash the inside of the benches with hot lime and allow to dry before refilling with the new earth. Four inches of soil is enough, and should be of equal depth all over the bench, especially along the edges. The soil should be fairly moist, but not wet when the plants are set, so that the roots may draw moisture from the soil rather than have the soil draw the moisture from the roots. On the other hand, soil for potting or planting should never be handled while in a wet condition. If too dry at the time of filling the beds, water, and let stand long enough to dry to the proper state before planting.
Apply a light shade of lime or whiting to the glass, to break the fierceness of the summer sun until the plants become established. This shade should not be too heavy, nor intended to darken the house, else a softening and weakening of the growth will result. Lift the plants carefully by means of a spade and leave a ball of soil about the size of the fist on the roots. This ball of soil will greatly assist the plant in reestablishing itself in its new quarters. However, no serious harm will be done should all the soil crumble from the roots without breaking the roots to any considerable extent. Set the plants just about as deep into the soil as they stood in the field and space them about 9 by 12 inches, if plants are of ordinary size. Larger plants may need more, smaller plants less space. It should be borne in mind that the highest quality may be expected only when the plants are not crowded. After setting a few hundred plants, water each plant individually, saturating the soil thoroughly around each plant, but do not soak the whole bed until the roots become active and the surface of the soil has been worked over and leveled off, which will be about ten days after planting. Spray the plants overhead several times during each day to prevent wilting. Keeping the walks wet will also help to maintain a humid atmosphere until the roots are able to supply the plants with moisture. This transplanting is an ordeal during which the plants are unable to draw on the roots for support until they have taken a new hold on the soil, and wilting must be prevented by artificial means during this time. To allow severe wilting means loss of foliage and a loss of vitality, which results in inferior quality in at least the early part of the season.
As soon as the soil has been leveled off, and most of the weeds gotten rid of, the supports should be put in place. Large growers use one of two styles of supports, or a combination of the two. Wires run lengthwise between the rows, with cotton strings crosswise, placing two or three tiers one above the other to suit the height of the plants is extensively used. Another device is the carnation support, consisting of a wire stake with wire rings to surround each plant.
Yield of bloom.— Plants that were benched in the latter part of July, or early August, which is the time to plant for best results, should begin to yield blooms early in September. If flowers are not desired so early, the stems may be broken off about the time the bud appears, but no general topping should be done after the plants are housed, if a steady cut through the season is desired. Cut the blooms during the early part of the day. They are then fresh and retain their natural colors, much of which would be bleached out of the delicately colored sorts by the sun during a warm day. Place in water at once in a cool room as near 50° as possible. Sort the blooms in separate colors, making two or three grades of quality, tying them into bunches of twenty-five blooms. Cut the stems even at the bottom and replace in water. Avoid crowding the blooms while they are soaking up water, as they will increase 25 per cent in size during the first twenty-four hours in water.
During a season, running from September to the end of the following June, an average cut of twenty blooms per plant may be expected from most varieties. Varieties differ somewhat, according to the size of the blooms, the smaller-flowered sorts usually being the freer bloomers.
The preparation of the soil for growing carnations is of the greatest importance. Choose a piece of land which has not been tilled for some years, if possible. If covered with a heavy sod, all the better. The soil should be a loam of good substance, with an inclination toward sandiness. Break this sod in the fall and leave in a rough state during the winter. In the spring plow again and sow to cowpeas or some other leguminous crop. After plowing this under in the fall, manure heavily and leave until the following spring when it should be plowed again. This soil should be in first-class condition for use the following summer. In working or handling soil, always bear in mind that to handle it while it is wet is to ruin it for immediate use. Only freezing will restore it again. If it will crumble readily, it is safe toss handle. Soil which has been prepared in this manner will be rich enough to carry the plants until after the first of the year, when light feeding may be given. Feeding should be done judiciously during the short days of winter, to avoid softening the growth and bloom. Pulverized sheep- manure, dried blood and wood- ashes are used mostly for this purpose. The manure and blood improve the size and quality of the bloom, and the ashes strengthen the stem.
Ventilation and temperature. — The carnation being a cool-temperature plant, abundant fresh air and ventilation should be provided for. A steady temperature is essential to success in growing carnations. Splitting of the calyx may usually be traced to either irregular temperature or to overdoses of feeding. Any point between 48° and 52° will prove a satisfactory night temperature for most varieties, providing it is evenly maintained. The temperature should be 10° higher during the day. Care should also be exercised, when building, in placing the ventilators, so that the atmosphere in the house may be changed without causing cold drafts to strike the plants. By placing the ventilators alternately on both sides of the ridge, this may be accomplished. The side ventilators are used only during mild weather.
The modern type of carnation house runs east and west, is of even span and is 30 feet or more in width, having ventilators on both sides of the ridge and in the side walls, if houses are detached. Many ranges are connected by gutters 6 feet or more from the ground. When economy in ground is necessary, this is a good plan, but such ranges always contain some benches inferior for growing stock on account of the shade cast by gutters. The single detached house is ideal. See Greenhouse.