This section is from the book "The Gardener's Monthly And Horticulturist V29", by Thomas Meehan. See also: Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long.
The time of blooming in Camellias is best regulated during the growing season when, by prolonging the warm treatment that the plants receive whilst making their growth and setting their flowers, the buds will keep on increasing in size, so that there is not much difficulty in getting them to open in the winter months, or even much earlier, if required, as by a continuance of the close, warm treatment after the setting process is completed, the plants may be made to reverse their natural season of flowering. By this means, and varying the treatment with portions of their stock, some of the market growers have an unbroken succession of Camellia flowers for ten months, the first coming in towards the end of July, whilst the last are not over before the latter part of May in the succeeding year. But after the plants have been kept cool subsequent to the setting of the buds, they are very impatient of heat; any attempt to force them into bloom generally ends in the buds dropping. Yet when the flowers are wanted earlier than they would come in a greenhouse temperature, a little heat, say 450 in the night, may now be given the plants without danger of the buds dropping, provided the atmosphere of the house is not allowed to get too dry.
This must never occur, even when it becomes necessary to use heat to keep out frost. The kinds chosen for having their flowering thus slightly accelerated should be varieties that have a natural disposition to bloom early, such as the old double striped alba-plena variegata, and others that have a like tendency. - T. B., in Gardening Illustrated.