This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
As previously indicated, plants for the early crop should not be set in the open ground until about May 10 in the latitude of Philadelphia and New York. There is danger of injury from hard frosts if transplanted before this time, and such injury may result in a large percentage of the plants producing seed shoots, thus rendering them unsalable. Seedlings for the late crop may be transplanted in permanent quarters any time after June 20.
The time of planting in the field will depend largely on the varieties to be used. For example, Golden Self-blanching may be set out three or four weeks later than Giant Pascal and have time to mature fully before hard freezing weather is likely to occur. Many commercial growers do not transplant the late crop until nearly the first of August. In most parts of the North, it is better to transplant early in July. The date of transplanting, however, is not so important as to have the plants, as well as the ground, in proper condition before transplanting is started. Plants that are 3 to 5 inches high are much more likely to live and thrive than taller ones. The ground should be smooth, fine and moist. It is exceedingly important to have the rows perfectly straight and this can be accomplished by the use of a marker. A line may be used for this purpose, but transplanting may be accomplished much more rapidly by using a rope-and-peg marker.
Fig. 859. Celery planted thick, and the patch edged with boards. The "new celery-culture."
There is the greatest variation in the planting distances for celery. Some of the most intensive growers plant 7 or 8 inches apart each way. Others prefer to space the rows about a foot apart and have the plants stand 4 inches apart in the row. When such close planting is followed, it is known as "the new celery-culture" (Fig. 859)- The plants stand so close together when this method is used that they blanch themselves and it is unnecessary to use boards or other devices. "The new celery-culture" is better adapted to greenhouse and coldframe use, where the plants can be watered by sub-irrigation. When plants stand so close together, there is little circulation of air and heart-rot or other diseases are likely to occur in hot moist weather. The possibilities of a small area by use of this method are very large and the system appeals to growers who have only small tracts of land to cultivate.
A more common practice is to space the rows 18 inches to 2 feet apart and to set the plants 4 or 5 inches apart in the row. This method is now almost universally employed for Golden Self-blanching when boards are to be used for blanching the crop. When transplanted 4 by 24 inches apart, about 60,000 plants are required to set an acre. If horse implements are to be used in planting, it is better to allow at least 28 inches between rows.
Some growers prefer to plant Golden Self-blanching in double rows 6 inches apart, placing the plants 4 or 5 inches apart in the row. This plan is not universally popular because it is not favorable to the full development of every plant. Boards are also used for blanching when this system of planting is followed.
When soil is to be used for blanching, more space must be allowed between rows. Formerly the almost universal practice was to allow 5 feet between rows. With tall-growing varieties, such as Giant Pascal, this is not too much space to provide sufficient soil for blanching. When lower-growing varieties, such as Winter Queen, are used, the rows need not be more than 4 or 4 1/2 feet apart to give sufficient space for blanching with earth. The larger varieties of the green type should not be planted quite so close together in the row as Golden Self-blanching; for the best development of the plants, it is better to space them 5 or 6 inches apart in the row.
Growers who .plant both early and late varieties often alternate the rows. The early variety is removed first, of course, and then there is 4 feet or more of space between the rows of late varieties which are blanched with earth. Transplanting should proceed as rapidly as possible without undue exposure of the roots to the air. If the plant-beds are watered twenty-four hours in advance of transplanting, the plants may be removed with less injury.