On Wed, 31 May 2006 20:17:45 -0700, "Wally B"
wrote:

Why are the leaves on my tomato plants curling?

Are they curling up or are they curling down? Any
discolouration?

Normally caused by stress--upward curl too much water and
downward curl by too little water. There are other possible
stressors. See

http://gardenline.usask.ca/pests/tomato.html if discoloured and
other possible causes.