This section is from the book "Indoor Gardening", by Eben E. Rexford. Also available from Amazon: Indoor Gardening.
This plant is too well known to require any description here. Most amateurs undertake the cultivation of the greenhouse varieties, and generally fail with them because they give too much heat, too much water, and allow the red spider to work on them.
A soil of rather heavy loam suits the Carnation much better than a lighter one. Drainage should be perfect. Water should be given in moderate quantity, but it should be given with great regularity. The plants should be showered all over every day, if possible, to keep the red spider down. If this is not done this pest will soon ruin them.
If young plants are procured in spring, to grow on for winter use, they should be pinched back, at intervals during the season, to secure plenty of branches. If this is not done they are almost sure to develop into lanky, leggy plants with but few branches to bear flowers. They should not be allowed to bloom during summer. Hold them in reserve for winter. In September put the young plants into six and seven-inch pots. These will be large enough for them to bloom in. When buds show, apply a good fertilizer. If many buds appear, it is well to cut away some of them, thus throwing the strength of the plant into the development of large flowers from those you leave.
If one does not care to start her Carnations in spring, field-grown plants can be procured in early fall. These will be bushy, compact plants, often well set with buds when sent out. If this is the case, I would advise cutting away every bud, and not allowing the plant to bloom until later in the season after it has fully established itself in its new quarters.