Planting Depth in Cold Climates
In the far North the shallow planting of seed is recommended because of the cold soil temperatures. When seed is planted shallow, it is placed in the warmest part of the soil which speeds up germination which is very helpfull but also has one drawback, exposing the seed to drying out which occurs more frequently near the soil surface. Be sure the soil surface over the newly planted seed is well compacted to help retain moisture.
Keep the seed moist as it MUST NOT be allowed to dry out during the germination period or the young sprouting seedlings will be killed. Unlike mature plants, there are no visual warnings when the seed is too dry. The results, however, are very visual: the seed just does not come up. With this in mind, it is very important to keep the seed bed moist at all times. This can be done by first watering the seed bed, then placing newspaper or a piece of clear plastic over the moist row to reduce evaporation. The use of plastic is very helpful where water is in short supply or where watering must be done by hand. Clear plastic also raises the soil temperature, which in turn speeds up germination.
CAUTION: when clear plastic is used it is very important that the plastic be removed from over the seedlings as soon as the first seedlings break the soil surface. If the plastic is not removed immediately most garden plants, with the exception of sweet corn, will be sun burned. This will either stunt or kill the young seedlings.