In many geographical areas, young celery plants are started in seed beds, sowed in closely spaced relationship in the interest of conserving space. Many advantages accompany the use of seed beds and these include the fact that the young celery plants growing from such seeds can easily be shielded from too much sun by the use of certain open fabric material being arrayed in the manner of a canopy from the tops of poles that are spaced around the periphery of the seed beds. Most importantly, proper moisture control may be relatively easily achieved in seed beds, and also it is possible to use much less fertilizer in such an environment than would have been involved had the plants been started in an open field, with the young plants already spaced in the relationship in which they are ultimately intended to grow.
Celery seeds are quite small, and it has been conventional to build up their size to a standard diameter by a procedure in which controlled amounts of nutrient are applied to the exterior of the seeds. Many machines for dropping the seeds of standardized size at prescribed intervals in seed beds have been proposed, but in all known instances, these machines failed to drop seeds at a consistently even spacing, and furthermore tended to drop the tiny seeds in multiples from time to time. As a result, two, three or more plants often sprouted very close together, resulting in plants that were considerably undersize.
As a consequence of the resulting seedlings being of widely varying size, a considerable amount of "stoop labor" was always necessitated, for someone must work the seed beds very closely, selecting only seedlings of a uniform size for planting, thus to assure that the final celery crop will be sufficiently uniform in size that it can later be harvested by mechanical means.
For many years it has been conventional to then set the selected seedlings out in open fields by the use of large, slow moving machines upon which a number of laborers may work. These laborers sit facing rearwardly, adjacent wheel-like devices that are operationally mounted at above-ground locations, with these devices being caused to rotate in the direction of machine travel, at a speed corresponding to the ground speed of the machine. Various "fingers" are mounted around the periphery of each of these wheels, which fingers are arranged during wheel rotation to come close to the ground. The arrangement is such that each laborer, by working rapidly, can place a seedling between each pair of these "fingers" as the machine travels through the field. The laborers must be dextrous if they are to avoid creating a gap in the particular furrow they are planting, and, as a matter of fact, it is customary to have one or more persons following behind the machine, placing plants in missed spaces.
It is quite obvious that the laborers assigned to place plants in the wheel-like devices have no time to perform any sort of selection with respect to the seedlings they are placing on the wheel-like devices, and therefore in the ground. Accordingly, the laborer responsible for pulling the seedlings out of the seed beds is in effect responsible for the final celery crop being of uniform size. Unfortunately, the plants grown in the seed beds that are passed by as a result of being too large or too small are usually left to wither and die, although this represents a sizable amount of the initial investment of seeds, fertilizer and labor.
To all acquainted with this art, it was obvious that what was needed was an automatic seeder able to plant seeds at such a consistant spacing that plants of extremely uniform size would result, thus making it possible for a seed bed to be stripped only once, instead of it being necessary to strip several times, each time making decisions as to which plants were of proper size.