As previously explained, plants for the early crop should not be set in the open until after danger of severe frosts. In most sections planting should not occur until May 10 or 15. Strong, vigorous plants properly set at this time should produce a marketable crop by August 1. The late plants may be set the latter part of June and throughout the month of July, depending upon variety, soil, weather and climatic conditions.
If the plants are more than 5 inches high at the time of transplanting, it is an advantage to clip the tops. This operation is sometimes repeated several times in the seed bed to induce stockiness.
The ground should be fine, smooth and moist before transplanting is begun. It should also be fairly firm and marked at the required distances. Various forms of markers are employed, but shoe and roller markers are most popular. The roller markers may have pegs to mark the place for each plant, to secure uniformity in spacing. They relieve the foreman of the annoyance of looking after this matter.
Planting distances are extremely variable. If soil is to be used in blanching, the distance between rows must be not less than 3 l/2 feet; 5 feet is the more common spacing, especially for the tall green varieties. Sometimes an early variety, as Golden Self-Blanching, is planted in alternate rows. This variety is blanched by means of boards. The distance in this case need not be more than 30 inches. After the early crop is sold there is ample space to blanch the late crop with soil. When boards or other devices are used for blanching the spacing between rows varies from 18 inches to 3 feet. In the most intensive plantations where boards are used, the distance between rows is usually from 20 to 24 inches. The standard distance between plants in the row is 6 inches, although there is a decided tendency to plant closer. Some of the best growers plant the early varieties only 4 inches apart and allow 24 inches between rows. At these distances 65,000 plants are required for an acre.
Double row planting is practiced occasionally. With this method the rows are about 6 inches apart, and either earth or boards may be used in blanching.
When the plants are set very close together both ways, as 8 x 8 inches, or closer, the method is known as "the new celery culture." Like other intensive methods, it is adapted to only very fertile lands where the supply of moisture can be maintained. With this plan there are usually 5 to 10 rows in a bed with 2-foot alleys between them. When all the points are considered, it is better to plant 4 x 24 inches apart, so that a wheel hoe can be used in cultivating. Close planting is not so well adapted to the green varieties because of the greater difficulty in blanching.
Transplanting can be done to better advantage in humid or cloudy weather. The plants should be lifted with care. If the seed beds or flats are watered 24 hours in advance of planting, the plants can be removed with more soil clinging to the roots than if unwatered. Some growers give little attention to this matter and often shake most of the soil from the roots. In this case the roots are usually puddled before setting, or the ground may be watered before and after planting. Dibbers, trowels, or the forefingers are used in making the holes to receive the plants, which should never be set deeper than they stood in flats or beds. Pressing the soil firmly to the roots completes the operation of transplanting.