My tomato vines are yellowing at the bottom.
Certified GKH Gardening Expert
There are a number of reasons for leaf yellowing in tomatoes. If the leaves are curling and there is little yellowing on the plant or just the bottom leaves, the curling is likely environmental and not an issue. If the plant is yellowing as well, especially accompanied by spotting or wilting, it is likely disease. This article should help with pinpointing and correcting the cause of yours: https://www.gardeningknowhow.com/edible/vegetables/tomato/yellow-tomato-leaves.htm