Worked like a charm this time. Rooted seeds of nearly all ‘difficult’ samples and almost all of them looking perfectly healthy.

From these last series, they’ve received a long warm period and will now go into cold storage. Here the two extremes in seed size: P. ludlowii (or a hybrid with P. lutea/delavayi) versus P. tenuifolia (P. biebersteinia). The latter one is quite prone to rootlet rot is my experience, but no problem this time.