Why are my tomato plants curling up?

I have tomato plants(Arkansas Travelers and Better Boy) whose leaves are curling, and one has died. Why?

Why are my tomato plants curling up?
Maybe not enough water or too much fertilizer
Reply:If your leaves are curling and have purple on them its a lack of phosphorous..Bone meal can take care of that. I dont know what has been applied to the soil. Too much fertilizer will kill them . Too much water will kill them... Too little water will do that as well. There are many things that can cause what you describe. I have just planted 27 better boy tomatos and have no problem with them yet.. I allways sprinkle bone meal or blood meal in the hole befor planting. I plant them deep. Which means removing a few branches as tomatos will send out roots along the stalk which is what you want..Get a good root system and the rest is easy. Maybe its too cold in your region to plant, or too hot..it never ends.
Reply:Tomatoes are pretty drought tolerant. The less water you give them the better they'll fruit. But when they are young they need a bunch of water to get started. I know some varieties are susceptible to tomato diseases like fusarium wilt. But if the leaves are curling and getting crispy, I'd say not enough water. Good luck.