ZZ has now told me how the Czechs root Daphne cuttings
1/ First he used yellow field clay, later blue clay, now he tried to add sand and another elements (all are working well).
2/ No food added (he added only stimulating/?rooting powders into clay).
3/ Charcoal is only to dip cuttings for disinfection of the cut.
4/ First working size was one inch in diameter, now he reduced it to 1cm.
5/ Mostly in classic time after blooming (semi ripe state) but also in autumn for rooting in winter glass garden); he says: all year around when the plants have the urge to propagate itself.
6/ The balls are sunken half way in wet sand in translucent plastic boxes (with lids) in warm old shed behind large side window. I wish good luck to all daphnefyls. Zdeněk