My 3 potted dwarf citrus trees are cupping upwards/inwards. I suspect this may be due to over or under-watering...probably over-watering. Their pots are plenty big enough and the soil is the 5-1-1 with softwood bark, peat moss compost, perlite, and 1tbsp of lime. The trees are all on a porch and they get 6-7+ hours of direct sun a day. Since the leaves are cupping so uniformly, I don't think it is insect action.

Here you can see the issue:
http://www.druble.com/wall?d=1lf

I have a moisture meter that reads from 1 (dry) to 10 (wet). When should I water based on the meter? Should I wait until the soil has completely dried out and hits 1 on the scale? Or should I water it again when the soil is just on the drier-side...3 or less?