did you fertilize? kind of looks like burned from over fertilization. something drastic changed for them to turn like that in a week...
peppers don't like a lot of water, so don't water them until the soil feels at pretty dry. that is probably why they are also starting to yellow.. unless you haven't given them a mild fertilizer yet? what kind of potting mix?
also, the soil does look a bit wet.. let the first 3 inches of soil dry out a bit before you water.

They appear very anemic to me in the photo, even the new growth isn't nearly as dark green as it should be. That usually indicates one of two possibilities - over-watering or lack of nutrients. And the leaf edges could be just necrotic tissue from lack of nutrients. So what, how much and how often have you fed them and what mix did you fill the pots with?

They are also in pots that appear too small even for this container variety. 5-7 gallon containers are the size recommended for Patio Star. What are the dimensions on the pots? They may already be root bound in those pots.

Dave

I don't know if the soil has sunken a lot since planting, but it's better to completely fill the pot, especially if you aren't providing it with a large enough planter in the first place. I actually haven't had the best luck growing zucchini in pots, they do so much better for me in-ground (I haven't tried the varieties meant for container gardening though).

The only fertilizer I've provided was when I planted the seeds (early June). I mixed some granular Epsoma Tomato-tone right in to the soil. The wet soil in the photos is a result of a lot of rain yesterday and last night.

I suppose I may be overwatering. I've been nervous about under watering since they're in pots.

The soil has sunk in the pots. I filled them pretty much to the top originally but didn't want to overcompact them. I'm not sure of the pot size. Will check when I am back home, but I believe they are at least 12" diameter.

So maybe they just need some fertilizer and less water?

"The only fertilizer I've provided was when I planted the seeds (early June). I mixed some granular Epsoma Tomato-tone right in to the soil. So maybe they just need some fertilizer and less water?"

Then they most definitely need some feeding ASAP! But with containers using liquid water soluble fertilizers is better than using dry granular ones, especially if the granular one is an organic fertilizer like Espoma. Organic dry ones are great in the ground where there is soil bacteria to digest them but those bacteria don't exist in containers. And, as always with any container gardening, you have to supplement the nutrients regularly every 10-14 days as they drain out of the pot every time you water.

As for watering, of course the best way is to be exactly right ;-) but if you have to choose between over or under then go with under for the plant's health.

In general, a 12" pot unless it is very very deep is only 2-3 gallons. Compare your pots to a 5 gallon bucket in size (which is only really 4.5 gallons) and consider transplanting them to at least that size minimum.

Dave

cucumbers/zucchini/melons need a bit more water than other vegetables, but it's almost impossible to underwater peppers, they actually prefer dry soil. almost every vegetable out there will wilt days before a pepper plant will.. they are almost desert-like plants.
for stuff like in your situation, i prefer a 5-1-1 fish emulsion because it has instant fast acting nitrogen (around 3.50-3.75% is soluble) and it doesn't have big risk of fertilization burn, after you can switch to a more balanced fertilizer .

The pot diameter is just about 13" at the top, 8" at the bottom, 12" tall. So if my math is correct, it's probably on the order of 4 gallons completely full, so certainly smaller than ideal I guess. However, I'm hesitant to transplant them now - don't squash "dislike" being transplanted? I will try to deal with the pots I have and reduce my water and add some liquid fertilizer, as much as that sounds contradictory! :) I will get larger pots next year.

I have some Neptune's Harvest Fish & Kelp Emulsion (2-3-1). Will that be OK? Who makes the 5-1-1 fish emulsion?

BTW, thanks all for the help.

Perfect. Thanks! I'll try to report back with any improvement...or, gasp, further deterioration

Well, I managed to give the plants some fish and kelp emulsion once and then we proceeded to have rain, rain, and more rain this week. Certainly not good for anything suffering from being overwatered. Here's the plants now. Looks like they COULD do ok if it just weren't so wet here - the new growth is looking ok. Though the old leaves are cooked and they've decided to start flowering. I don't think we're going to have zucchini this year

One of the advantages of growing in containers is that they don't have to be exposed to all the rain like an in ground garden that can't be moved is. You can always bring them indoors, shift them under a protected overhang or patio table or easily cover them to protect them from heavy rains.

Cut all those old dead leaves off the plants. They are only causing it more stress. There is no benefit to ever leaving them on any plant.

Dave

You could top up the soil level in the pots. Zucchini will root from the buried portion of stem.

Those pots are probably way too small. The plants look overwatered and underfed.

I would start over. It is not too late for some fall zucchini.