The soil looks very dry. If you're unsure of when to water you can use a dowel/bamboo skewer and insert it in the soil 4-6 inches. If it comes out just slightly damp, it's time to water.

It could just be the photo, but the leaves look very green. Fertilizer can burn, too.

Well I don't use any fertilizer, and the many of the leaves are green, but the curl downwards. So anybody else have an idea?

Hmmmm, I now believe that the problem of my tomato leaves is under watering.

How often do you water and how much?

As a general rule, tomatoes need an inch of water every week. An inch of rain is exactly that, water that is one inch deep. One inch of rainfall equals 5.6 US (4.7 Imperial) gallons of water per square yard. Cool weather or soil with lots of clay needs will be less, hot weather or sandy soil will need more.

Dig down with your finger about 4", is the growing medium wet, dry, or just right? If it is wet, don't water, if dry then water. If it is just right, check again the next day. Water deeply once or twice a week. Watering daily encourages shallow roots which means the plant is affected more by variations in soil moisture. In my garden during the heat of the summer, I water deeply every 4-5 days, early spring I may only water every 8-9 days and when the weather is moderatly warm (70-80 degrees F), about once a week.

Mulching heavily (to a depth of 6 - 8 inches) with compost, straw, hay, rotted leaves, grass clippings, even shredded paper or sheets of paper or cardboard helps maintain a consistent moisture level.

Betsy

Ok, Bets, thanks.