This is an important stage in the cultivation of plants which have been raised from seed. As soon as the young seedlings can be handled easily, they must be moved on into deeper boxes which will provide their roots with more room to develop. If the seedlings are left in their original boxes or seed-pans too long, they will become badly drawn or straggly and they will not grow into sturdy specimens.
The boxes for the pricking out stage should be a little deeper than those used for the seed sowing. They should be prepared in the same way by first placing some rocks over the drainage slits or, if plastic ones are used, these will not be necessary, and some of the coarser sievings should be placed over the base instead. The best compost to use is the John Innes seed sowing formula.
All boxes must be thoroughly clean before they are used. As the soil is placed in the boxes, it should be firmed gently with the fingers and, finally pressed flat and even with a piece of board. The finished surface should be about 12mm (1 in) below the rim of the box.
The seedlings should be removed carefully from their seed box by levering them up with a light piece of plastic or wood. Roots must be disturbed as little as possible. Seedlings must be held by their seed leaves, never by the delicate stems otherwise they will be damaged. For tiny seedlings, a forked piece of plastic or wood will be found to be the best device for handling.
The holes for the seedlings should be made large enough to accommodate their roots comfortably. A round-ended dibber is ideal for this work. Seedlings are best picked out in rows, spacing each seedling about 5cm (2in) apart each way. As each box is completed, the soil should be given a light watering with a fine rose placed on the end of the can.
Keep the seedlings in a warm damp atmosphere for a day or two after picking out has been completed. Shade them from strong sunshine otherwise, the seedlings will wilt badly. Afterward the boxes should be given normal conditions.