The sowing medium (peatmoss) should be a uniform dark colour and by not adding perlite/styrofoam/vermiculite it enables one to see the white radicle as it starts to emerge and at about 1 cm in length planted into cells or pots. Tweezers are perfect for scratching in the seed tray, picking out (carefully) the seed from the peatmoss, prodding a hole in the new medium and setting the seed, radicle down. If the radicle is a bit long, you run the risk of setting the seed with a bent root so a little pruning of the tip of the rootlet may be necessary, snipping scissors work well for this purpose. At 1 cm long the emerging radicle has no root hairs, therefore there is little chance of interrupting development by this procedure. When the radicle is a few centimetres long, the delicate root hairs are just starting to grow at the top and these are very fragile.
At cotyledon emergence the cotyledons have control and afford protection – I prefer to think of the cotyledons as providing “mothers milk” – the perfect nutrients for the young plant. As for planting out the seed at radical emergence, my feeling is that the emerging seedling will naturally develop to the best surface level between the stem and the roots. If the seedling is potted-up too deep, this level can be below the surface and if kept too wet can afford an entry point for damping off and other problems.
Planting out from seedling trays into pots runs the risk of planting too deep, planting with a bent root or disturbing hair-like rootlets just starting to form. I find that planting the emerging seedling into a small cell at the radical emerging stage and allowing it to grow to just after cotyledon exhaustion stage is a better option as it is easier to pot up then. (Figure 2) Proteas hate their roots being disturbed so great care is needed here, especially after the cotyledon begins to exhaust itself. A drench of 5 parts seaweed extract (10ml per litre) plus fulvic acid (14 ml per litre) and salycilic acid (200 mg per litre) and sugar (2%) a few days before potting-up will be beneficial.