CARNATION: FOR GREENHOUSE AND OUTDOORS
Carnations in all their various forms are generally considered to be derivatives of Dianthus Caryophyllus, although the origin of some is not entirely clear. In North America, when referring to Carnations we immediately think of the Carnation of commerce, the continuous or Perpetual flowering Carnation that is commonly grown under glass. There are, however, various garden types of this delightful flower that have never become so popular in North America as they are in many parts of Europe; this is because over much of the continent temperatures are too high for their successful, easy culture.
Greenhouse Carnations. Carnations of kinds that are commonly grown by florists and gardeners in greenhouses are cultivated, almost exclusively, as cut flowers. They are essentially fall to spring bloomers and so supply blooms at a season when they are most highly valued.
They are started from cuttings, about 3 in. long, taken either from the base or bottom half of the stems of old plants. Cuttings made from shoots from a little above the base give the best results. Moderately strong cuttings produce heavy plants more quickly than do short or spindly ones. They can be rooted in about three weeks in a sand propagating bed in a temperature of 40 degrees. If the sand can be kept five degrees warmer than the air by the use of bottom heat, roots develop more quickly. Some growers use a hormone preparation on the cuttings before planting but this is not necessary if the environment is conducive to root formation. December and January are the best months for inserting cuttings.
To prepare the cuttings remove the leaves from the shoots for about % in. from their bases so that no leaves are buried in the sand. Make a clean cut across immediately below the lowest node of each cutting. Cut back long tip leaves to half their length to avoid excessive wilting before root growth has developed. The cuttings are then ready to insert in the sand. Plant them in rows across the bench. Make certain that each variety is correctly labeled.
When roots have formed on the cuttings the new plants must be moved to growing quarters.
Commercial growers often plant them 3-4 in. apart in bench rows but it is better for most home gardeners to pot them singly into 2 1/2-in. pots, using a well-drained soil that has lime and bone meal added at the rate of a 4-in. potful of each to each bushel of screened soil. Line the newly potted plants across the greenhouse bench, pot touching pot, and again make sure that each variety is correctly labeled.
The young Carnations should be given full sunlight, except for 2 or 3 days immediately after potting, when they benefit from shading with cheesecloth or newspaper. The night temperature should be around 50 degrees and ventilation should be given during the day when sunny, except during severe frost. When the roots envelop the soil ball in the pot, which will be in 5-7 weeks, the plants should be repotted into 4-in. pots, using a similar soil mixture to that used at the first potting.
In the early stage many of the plants will send up flower growths. These should be pinched out never near the top but, instead, at 3 or 4 nodes from the base. From time to time pinching will be necessary to induce branching and bushiness. Pinching is continued until mid-September. At each pinch after the first one, it is necessary to cut the growth back to a point 3 or 4 nodes below its termination, otherwise the formation of a new side growth is not likely to be realized.
At one time it was common practice to set the plants from 4-in. pots into good soil in the garden, and to transfer them to the greenhouse bench, or to 8-in. pots in September. It has been found that Carnations can be grown with less risk of disease if they are planted in the bench directly from the 4-in. pots. May is the ideal month to do this although most gardeners find it impossible to find the necessary space before June. It is very helpful; however, if the plants get a start in their flowering quarters before excessively warm days come along.
When planting in the greenhouse, fresh soil should be used that contains at least 25 per cent decayed organic matter; a dusting of lime and superphosphate or bone meal should be incorporated with the soil before planting. Space the plants 8-10 in. apart, setting them rather high to avoid stem rot disease; it is advantageous to form a slight channel at planting time between the rows so that water that is applied soaks to the roots without settling near the stems.
Supports. Many varieties never grow more than 2-3 ft. high; others, with good culture, will stretch 5 ft. It is necessary to know ahead how tall each variety grows to allow sufficient headroom and to make provision for supports. Supports should be installed soon after planting so that the stems remain erect. The usual practice is to fix vertical frames of galvanized pipe on the greenhouse bench and from these, horizontal nets of 16-gauge wire are stretched, a wire between each row along and across the bench so that each plant has a square of the net or mesh through which it grows. As the plants grow, additional tiers of wires are installed.
If only a few plants are grown and flowered in a bench or in pots, there are various other plant supports available that suffice, but Carnations should be grown in fair numbers only. A minimum of 100 plants is needed to make sure that a good vase of flowers may be cut at any one time.
To secure good flowers disbud the plants by removing, while they are quite small, all buds except the terminal one from each stem.
Carnations quickly utilize the nutrients in the soil and during fall and winter, except in sunless weather, and through spring, light applications of 5-10-5 or other complete fertilizer should be made every three weeks; apply the fertilizer just before giving water.
To keep the foliage a healthy-looking, blue-green throughout the flowering season, and to avoid, as far as possible, damage from calyces splitting; the maintenance of a dry atmosphere; copious ventilation without drafts; a night temperature of 45-50 degrees; and thorough watering only when the soil appears to be becoming dry; these are all important.
Soil-less Culture. The Greenhouse Carnation thrives on this method of culture. Some commercial growers have adopted sand or gravel culture, and some amateur growers have been very successful with the hydroponic cultivation of Carnations. True hydroponic culture is carried out with a shallow tank filled with gravel or small shingle (stones), which act as an anchorage for the roots of the plants, the nutrient solution being pumped into the tank to feed the plants by sub irrigation.
A popular and easier method not requiring a tank or pump is that known as Sand Culture, for which a sharp sand, neither too fine nor too coarse, is required. The plants are grown in benches or pots filled with the sand and fed with nutrient salts in given quantities and at prescribed periods. The nutrients, in addition to the three basic plant foods, nitrogen, phosphorus and potassium, include the trace elements such as boron, and magnesium. The types of sand available for this work are numerous, but most growers prefer a sharp, gritty, washed, river sand. There are different formulae of nutrient salts which are recommended for use according to the season of the year. While soilless culture is both useful and interesting, it calls for care and attention and the need to work strictly according to the instructions laid down by those who have studied the subject. The subject is dealt with under the heading of Hydroponics.
Varieties. Some of the best modern Carnation varieties for the greenhouse are:
White: White Sim, George Allwood, Northland, Purity and Olivette.
Pink: Pink Sim, Laddie, Donna Lee Supreme and Sidney Littlefield.
Scarlet: William Sim, King Cardinal and Scarlet Pimpernel.
Deep Red or Crimson: Suzanne, Mrs. C. W. Weld and Seth Parker.
Yellow: King Midas, Miller's Yellow and Golden Wonder.
Two-toned Varieties: Dairymaid, white ground, striped pink towards the edge of the petals; Eastern Wonder, deep heliotrope, shot with deep
pink; Pelargonium, white ground, blocked crimson-maroon on each petal; Peppermint, white with red stripings; Scarlet King, bright red with petals edged creamy-white.
The outdoor cultivation of Carnations does not receive much attention in North America, but in Great Britain and some other parts of Europe varieties of Dianthus Caryophyllus, particularly adapted for growing in the open garden, and known as Border Carnations, are much cultivated.
Where winters are severe, Border Carnations are not reliably hardy, but in California and some other favored parts they may be grown as perennials, and some named varieties are available. They thrive best in a fertile, well-drained soil that contains some lime, and in a sunny location. They are propagated by cuttings and by layering. Seeds give plants that flower in 6-9 months but seedlings do not truly reproduce their parents; considerable variation occurs among them.
Two other types of Carnation suitable for growing in the garden are well worth growing, the Grenadins and the Marguerites. The former normally bloom in their second summer from seed and are hardy in the North provided they are planted on rather light, well-drained ground and are lightly covered over winter with a layer of evergreen branches or salt hay. The seed may be sown directly outdoors in spring or early summer and the seedlings thinned to 6-8 in. apart.
Marguerite Carnations bloom the first year from seed and are often treated as annuals and discarded at the end of their first season of bloom. They are, however, truly perennial and are hardy in the North if given the care recommended above for Grenadin Carnations. For early bloom it is best to sow Marguerite Carnations in a greenhouse 8-9 weeks before they may be planted outdoors, but seeds sown directly outdoors about the time the trees are breaking into leaf will give good flower the first summer.
All outdoor Carnations need full sun and should not be crowded together or among other plants. They are good subjects for seaside gardens. For the best results new plants should be raised fairly frequently; old plants usually begin to deteriorate after their second or third year.