Something I left out of my earlier postings on this subject. I top-up the base fertiliser in the commercial compost, having diluted it with grit and bark etc. by adding some blood, fish and bone (meal). In summer, not relevant to nerines which are mostly dormant, I use miraclegrow, and in winter when I very occasionally feed the winter growers, I use a liquid tomato food. I have also recently tried using a potassium sulphate on bulbs once or twice in the season. See the SRGC bulblog for more details on this link http://www.srgc.org.uk/bulblog/300103/log.html but also at other times since. Brian Whyer, Buckinghamshire, England, zone ~8