The soaking of seeds before sowing is of doubtful value. It may be the means of hastening germination a few days, although sowing earlier will accomplish the same purpose. When plants are killed by frost and it becomes necessary to make another sowing a slight gain will be made by soaking the seed. Most growers, however, never soak any kind of seed before sowing.
Some crops may be grown from seed sown broadcast, but this is impossible with plants requiring frequent cultivation. Thousands of farmers always broadcast turnip seed, while drilling is a common practice among truckers and market gardeners. Broadcasting is not without merit. It may be done very quickly, and the individual plant often has a better chance for full development than when grown by the drill method. This is particularly true with seedlings that must be transplanted. Some growers of late cabbage plants always broadcast the seed, because they claim that the plants are stronger and stockier than plants grown in drills without thinning. The same remarks apply to lettuce, whether sown under glass or in the open. Most of the arguments, however, are in favor of drilling, and the advantages over broadcasting may be enumerated as follows: (1) By sowing in drills it is possible to cultivate the soil. This is exceedingly important with practically all crops. (2) It is easier to thin when the plants are in rows than when they are scattered. When properly thinned they should be just as strong as when grown from seed sown broadcast. (3) The seed is sown at a more uniform depth, especially when machines are used. (4) In plant boxes or small seed beds water may be applied between the rows. This is often a great advantage when damping off is likely to occur. (5) In stiff soils the percentage of germination is greater, because the seedlings assist each other in their effort to reach the light. (6) Seedlings come up straighter, and may be arranged in a more orderly manner when pulled for transplanting; therefore, they may be removed more rapidly from the seed bed, and also handled with greater speed when transplanting. Both of these advantages are well worth considering when thousands or perhaps millions of plants are to be shifted.
Sowing by hand in the open ground is commonly practiced by home vegetable gardeners. Lines or markers should be used at such times to secure straight rows. The furrows may be opened with' a small shovel of the wheel hoe cultivator or with a rake or suitable hand hoe. One of the best ways to make a shallow furrow for small seeds is to stretch a line and follow it with the back of the garden rake which will make a neater furrow than any other tool. The seeds should be dropped at uniform distances in the furrow, and if they are small, as turnip and radish seeds, a letter envelope may be used to advantage. Seal the envelope and cut one end off; after placing several tablespoonfuls of seed in it, move it slowly over the row, shaking back and forward as may be required to secure an even distribution of the seed. After some practice seed may be sown more rapidly in this way than is possible with the thumb and fingers. The furrows may be closed by using hoe, rake or hand plow, the method used depending upon the required depth of covering.
When sowing under glass the usual plan is to make the furrows with a piece of lath or a straight-edge, or perhaps with a pot label drawn along a straight-edge, then to sow with thumb and fingers or with an envelope, as just indicated, and to cover with the fingers, or any device that may be convenient. For more complete information on this subject, see Chapter XVI (Growing Early Vegetable Plants Under Glass).
Seed sowers or drills are now indispensable in commercial gardening, because they do the work so much better and more rapidly than is possible by hand sowing. The seeds are deposited before the soil has had time to dry out; the depth of covering is uniform and the soil is compacted after sowing; the rows are also straighter and the seeds can be dropped in hills, if this is desired. There are several standard makes of seed drills, all of them satisfactory when properly used. Figure 29 shows the drills used most extensively. A wheel hoe and a drill are sometimes combined in one implement, but the tool is not very popular with commercial growers.
It is nearly always an advantage to firm the soil after sowing. By this operation the seed is brought into close contact with the soil particles which furnish the moisture necessary for germination. Compacting is especially important in loose soils, because it makes the capillary action stronger and insures a larger percentage of germination. Peter Henderson claimed that the most valuable chapter he ever wrote was on "The Use of Feet" in market gardening. He often had men step foot over foot on plats of several acres where the rows were only 1 foot apart. The modern seed drill does the same work, but with less force, and the roller is used sometimes for this purpose. After covering the seed, gardeners often pat the soil with the hoe blade or the back of the shovel. When sowing under glass or in small beds, sticks or blocks are generally used. Dense and compact soils need very little of the above treatment after seed sowing.
With an overhead system of irrigation it is often an advantage to water after sowing. In the management of crops under glass, the beds are nearly always watered thoroughly after sowing. The usual plan is to try to apply enough water to render further watering unnecessary until germination is complete. The watering of flats or beds by subirrigation is regarded as an advantage by some. The beds must, of course, be water-tight. Flats are often set in shallow tanks containing about ¾ inch of water, or more if necessary. The water soon rises in the soil by capillary attraction, and there is no danger of washing out the seed. Watering by sprinkling, however, is always satisfactory when done with care and intelligence.
Some soils dry out more rapidly than others, and some seeds must have a more uniform supply of moisture than others. For these reasons shading is often an advantage. In outdoor culture, lath screens (Figure 30) are frequently used. Just half the space is covered by the lath, so that no part of the bed is shaded all the time. A screen of this kind is easy to handle and provides good ventilation. Old carpet, burlap and paper are often used in shading beds. The screen or shade should always be removed before the young plants are injured. In greenhouse and hotbed work the seed boxes are often covered with glass, which conserves the moisture and also raises the temperature when there is sunshine.