Cut flowers droop because of bacteria which clog their vessels (3 November, p 59). Adding a mild sterilising agent containing aspirin or common bleach, if heavily diluted, can help. A very effective solution that lasts a long time is 25 parts per million silver nitrate plus a buffer of 75 parts per million citric acid.
The addition of sugar to a preservative mixture in amounts varying from 2 per cent to as much as 8 per cent will help to open buds, and sometimes prolong the life of flowers.
See www.umass.edu/umext/programs/agro/floriculture/floral_facts/presvcut.htm for a useful account.
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