Fine seed is usually sprinkled over the surface of the seed mix and need only be pressed down firmly onto the mix without being actually covered. Large seed needs to be well spaced to facilitate later transplanting. The use of individual tubes is an advantage when only small quantities of plants are required. This allows large seed to be sown one to a tube while fine seed can be thinned out as germination occurs to leave the strongest single seedling. After sowing, the seed bed needs to be kept moist and sheltered from drying winds and from rain.
Some sunlight is an advantage.
With overhead watering, a fine spray is necessary to avoid damage to small seedlings. The seed mix in the containers needs to be fairly moist before the containers are placed in the capillary bed otherwise the capillary action may not occur. The problem can be difficult to control without the use of a fungicide. The use of sterilized seed raising mixes and sowing so that seedlings are not crowded are the most effective ways of preventing infection. Snails and slugs can cause rapid destruction of small seedlings.