The difficulty with any method of propagation is that the sex of the plant cannot be determined until the plants produce flowers, and this does not occur until the second season, when the plants are universally regarded as being too old for the most successful transplanting. It is possible that the increased productiveness of male plants would overbalance the disadvantages that result from shifting the plants a year later than is approved by our best growers. Then, too, the one-year plants might be set temporarily in a special plat, with at least a foot between plants in the row, so they could be moved later with considerable soil to permanent quarters.
When rows of asparagus are ridged to the usual height, the shoots must make an additional growth of 5 to 10 inches before they reach the light, and if cut as soon as the tips appear above ground, the product is known as white "grass" or white asparagus. If the ridge is slight or only a few inches high and the spears cut at or only a few inches below the surface of the ground, the product is known as green "grass," or green asparagus.
In deciding which of these two kinds to grow the following facts should be considered: (1) There is a great difference of opinion regarding the two types. Greiner ("How to Make the Garden Pay," p. 143) says, "It is true that the lower end of each white stalk is apt to be somewhat tough and needs peeling and perhaps shortening, but the flavor is decidedly milder, and of a more refined character than that of the stronger flavored green stalks." A very extensive and highly successful grower of green shoots describes their flavor as "extremely delicate." Probably nine-tenths of American growers use only the green shoots on their own tables. (2) The stalks diminish in size after they reach the surface of the ground and, therefore, it takes more plants to produce a bunch of green stalks than of white. This difficulty can, without doubt, be overcome to a great extent by skillful seed and plant selection. (3) The demand for the green product is rapidly increasing. Our markets are paying better prices for green, and this possibly offsets the lighter production to the plant. (4) As the soil is not needed for ridging in growing green shoots, the rows may be planted much closer, thus increasing the yield to the acre. (5) High-grade white spears can be grown only in sandy soils, while there is no such limitation with the unblanched shoots. (6) It is more difficult to control beetles in growing green shoots, because the stalks are more exposed to their attacks.
Whatever points may be raised for or against each type, it is unquestionably true that green shoots are becoming more popular in all sections.
When it is realized that the asparagus plantation is to last 10 years or longer, too much thought and care cannot be given to the preparation of the soil. In the famous fields of France a common practice is to trench the soil to the depth of 2 or 3 feet before planting and to work in large quantities of manure. Formerly, trenching was popular in this country, but it has been abandoned among commercial growers. A study of the habit of root growth has led to the conclusion that little if anything is to be gained by unusually deep preparation.
Subsoiling is seldom practiced by commercial growers, and it is of doubtful permanent benefit. The soil should not be plowed deeper than its natural depth, but there should be complete pulverization to the full depth of the plow furrow. To accomplish this a disk or a cutaway harrow can be used repeatedly to advantage before plowing. This treatment is especially important when sod lands are to be planted. After plowing, the same types of harrows should be employed until the ground is in perfect condition. While it is customary to plant land that grew other vegetables the previous year, some of the most successful growers prefer to precede the asparagus plants with clover sod. The crop has been known to thrive remarkably well planted on land which has produced alfalfa for several years.
Earliness, high quality and large size are the factors that count for the most in securing remunerative prices, and liberal and intelligent feeding bear a direct relation to each of these requisites. The gardener expects a great deal of his asparagus plants; he wants them to produce salable shoots for two months or more and then recuperate sufficiently to yield a good crop the next year.
When starting a new field the plants should have all the food they can utilize. Soon after setting, 800 pounds of a 5-8-10 fertilizer should be applied along the rows, and a top-dressing of nitrate of soda used at intervals of three or four weeks. Rotten manure can be used profitably before planting. A similar treatment should be given the second year. The plants should then be well established and a different course of treatment given.
The supply of vegetable matter must be maintained. This may be done by applying annually 10 to 15 tons of stable manure to the acre. Much larger amounts were used some years ago, but more economical results have been attained by reducing the application of stable manure and increasing the amount of commercial fertilizers.
Manure may be applied in the fall, early in the spring or at the close of the cutting season. It is doubtful, however, whether application should ever be made in the fall, and there is a growing inclination to make such applications after the cutting season, rather than in the spring. All kinds of stable manures are satisfactory for asparagus. They should be applied between rather than directly over the rows. It is believed that mulching with manure over the rows is objectionable because of the tendency of the manure to draw the crowns of the plants nearer and nearer the surface. Furrows are often opened with a one-horse plow to receive the manure. This practice is questionable, because the plow necessarily breaks and mutilates a great many roots. The better practice is to broadcast the manure as evenly as possible between the rows, and to mix it with the soil, by the use of a disk or a cutaway harrow.