It may be because you're using containers. I had similar problems with some of my plants when they were in pots but after planting them in dirt the yellow leaves turned healthy again. I suspect there is a watering or fertilizing problem that containers magnify.

In a PNW climate, growing tomatoes in containers is one of the more reliable methods - easy to rotate annually to avoid disease issues, the soil in a container heats to a greater degree than inground soil and one can move the containers to maximize sun exposure and reflected heat to maximize ripening. If you follow recommended container growing methods that are based on a correct size, well-draining potting medium, adequate fertilization and watering and good sun exposure, you shouldn't have too many problems.

Tomatoes are prone to a variety of disease issues including fungal blights and viruses - the yellowing or withering of lower leaves and spotting is often an indication of blight conditions. Starting with disease free or resistant plants is always helpful. Yellowing can also indicate watering or fertilizing issues as well - you might want to explain your situation in more detail to get better help - how big are the containers, what kind of potting soil, how much sun do they receive, what type of watering/fertilizing regime, etc.

You've both given me things to think about. I have each plant in a five-gallon (or bigger) container. I just used regular garden potting soil (sounds like that could be a problem). They're in full sun on my deck with good drainage. I've been giving them a half gallon or so of water every other day. The only fertilizing I've done at this point (4 weeks after buying them at a very reputable nursery) is one tbsp. epson salts in a gallon of water. Please feel free to rip away at my methods and tell me everything I'm doing wrong!

As suspected it sounds like they are probably merely starving. If a slow release fertilizer is not mixed into the potting soil and you don't fertilize frequently through some other method then there isn't much for them to live on in a soilless potting medium. The frequent watering required with such substrates quickly leaches them badly. Otherwise, tomato plants are nearly tropical in their temperature requirements and will develop problems if exposed to less than summer-like temperatures. Much of the year nights are too cold for them here, plus they are susceptible to being shut down prematurely by late blight. There is a definite case for growing them under plastic in this region.

Epsoms salts is not a balanced enough fertilizer for tomatoes or any other plant grown in a container. As bboy explained, the lack of nutrients in potting soil and the need to replace leached nutrients requires a more complete fertilizer that contains ALL the necessary plant nutrients as well as trace elements. Osmocote added at the time of potting will help, as will any other granular organic vegetable fertilizer (Dr. Earth, Whitney Farms, etc.). And because edibles do tend to be heavy feeders or require higher nutrient levels to produce fruit, I'd supplement with a dilute liquid fertilzer periodically as well.

A bit confused about the soil you used. Is it garden planting mix, intended for use in a garden (inground) setting or is it potting mix, designed for containers? There is quite a bit of difference between the two and could impact how well the pots drain. And if you've got one plant per 5 gallon pot, the size is about right. Black plastic nursery pots tend to trap and concentrate the heat and are most effective for growing toms in a container situation. If you have selected varieties with a short harvest period - ideal for our short tomato season - and have them where they will get maximum heat and sun, they should be fine.

And it is always best to water very thoroughly when you do water. Saturate the soil mass so that the water runs out freely through the drain holes, then hold off on watering again until the top 2 inches of soil are pretty dry to the touch.

I've grown tomatoes, eggplants, and peppers in containers. Tomatoes do OK for me in the ground but not the other two. I use potting mix from a nursery bought by the yard, and add some perlite. I water daily on hot summer days using fish emulsion fertilizer. I agree, the yellowing and browning could mean they got low in water on a hot day.

Once again, I've learned so much from all of you.

Gardengal, I used potting soil meant for containers.

It sounds like I've got the pots and watering right, but, yes, I'm starving them. I'm headed to the nursery for some fertilizer as soon as it opens. I'll try to save these plants and start out right next year.

Thank you!

I think you still need to bump up the watering. 1/2 gallon every other day or so for a 5 gallon container is not enough. Water freely and thoroughly when you do, so that it runs out the bottom of the pot. 5 gallon containers may not need water everyday, depending on our weather, but they should be watered fully as often as necessary rather than in dribs and drabs on a routine basis. Irregular or insufficient watering can encourage blossom end rot as well as contributing to drought stress and general lackluster performance.

You may want to include fish emulsion as part of your fertilizing/watering regime. A half strength application every 10 days to two weeks will help to replenish necessary nutrients including providing a needed dose of calcium, which tomatoes require (another reason for blossom end rot).

Thank you, gardengal. I have been watering them until the extra water is running down the deck, so I think I'm okay there. It's easy to watch them carefully since they're right outside the door. I'll be sure to check them a couple of times a day. Eventually it will heat up, and I know they'll need daily watering.

I have some fish emulsion and appreciate the advice on how much how often. We're going to succeed! Thanks again for the advice.