I'm growing tomatoes for the first time this year in my backyard in the San Francisco Bay Area. They are coming along; some of them are now a couple feet high, and have blossoms, and a few have started setting tomatoes (Black Krim and Sungold). I've noticed that some of the lower leaves are yellowing (in most of them it's not the lowest leaves, just towards the bottom). I've searched around to try to figure out what the problem is, but I haven't really found anything satisfactory.

Here's what I've done so far: I started them from seeds, and hardened them off. Some of the plants got a bit sunburned because I didn't harden them off enough, but they all recovered. I prepared the soil by digging down 8-12 inches and mixing in compost and a little composted steer manure. I've found that they don't seem to want much water in our mild climate here, since some of them developed leaf roll after watering, so I now often go for two weeks between waterings (sometimes every week when we have hot weather). About two weeks ago I mixed in some 5-10-10 "natural" tomato fertilizer to the soil around half of the plants, though I haven't yet seen a difference between the fertilized and unfertilized--some of both have the yellowing leaves.

Attached are pictures of the yellowing leaves, and the last picture shows that it's only some of the leaves that seem to be affected.

Thanks a lot for reading this.

-Adam