So sorry about the extensive frost damage, Lorn.
The weather can give us some nasty surprises sometimes and it must be particularly hard to see those lilies you are most interested in getting the worst damage.
To answers Dave's original question, one solution to frost damage of large plants would be to use frost irrigation. Mist plants with water throughout the night/morning hours. There is energy released when ice forms on the plants. The ice needs to remain wet at all times for this to work. Too little water could do more harm than good, so this is something one need to be aware of. Could be problematic to do at home for various reasons and of course with lilies too much water could be very bad on heavy soils, but perhaps something to try in a desperate situation.
