The pepper plant is far too yellow but it is primarily the old growth that is yellow - that indicates excessive watering. While the new growth, somewhat better color but fading, has curled edged leaves - also indicative of a watering issue. So best guess on it is over-watering and in need of some nutrients. Peppers prefer to dry out some between waterings and do not require nearly as much water as tomato plants under normal conditions.

The "tiny tomato plant" - can't really see it well enough in the photo except to note again that it is pale - especially compared to the one in a different location. So again I suspect lack of nutrients.

As Dan said many factors can contribute but by far the 2 most common are water issues and nutrient issues. Address those two factors - cut back on water and feed them - and see if both don't improve. I also suspect nutrient issues because you mention that herbs are doing well. Herbs can thrive in nutrient poor soil, they prefer it in fact over high nutrient soil. So I'd sure give some thought to feeding your tomato and pepper plants.

Dave

The soil under that tiny tomato looks kind of like hardpan with rock-like clods. Has that soil been amended with organics to soften it up? Hardpan soil will interfere with root growth, and can manifest as a nutrient deficiency.

Not sure why my location isn't showing, but I'm in the SF Bay area in Z8-9 (San Jose). The plants are literally in the same bed, with the same light, the same dirt, the same additives, the same water source, timing, drip heads, etc. The only real difference is that the rain downspout is by the poorly growing plants (possibly washed out the nutrients?), and the ones growing comparably better are at the opposite end of the bed.

I used the word cruddy, because this is the same issue I saw last year, and my turnout was real bad. I almost didn't plant anything this year because of how bad things were last year.

The soil is amended this year with cover crop, and I don't think we have what would be called hardpan in California. It's more like loam, clay and silt mixed. Last year I added ~100 lbs of compost, and this year I planted the cover plants, so it's fairly well amended (I think).

I'll draw back on the water, and find a suitable tomato food because those two options seem easiest.

Sounds like a good approach. You've taken some trouble to amend your soil.

That's an interesting thought that rain from the downspout could have leached that soil of nutrients. To the extent that you get a lot of water coming down that downspout, I wonder if you couldn't direct the flow somewhere else. I believe that nitrogen, phosphorous and potassium loss from heavy rains are issues that commercial gardens have to take into account. Heavy rainfall can have a major effects on soil fertility. Nitrogen in the form of plant-available nitrates are especially mobile in this way.

I blame the proximity to the building foundation. I’ve seen many good plants grown close to foundations but usually the outcome is similar to yours. Dig down a few feet and replace the building contractor’s backfill with good topsoil.

As for the Ghost pepper- those usually look like that until they start to take a growth spurt. That doesn’t mean that peppers wouldn’t benefit from better soil.