If you aren't fertilizing them, to me that would seem to be the problem. No matter how wonderful a soil mix is, it probably isn't going to have the abundant supply of N and other elements fast-growing crops are going to need for rapid growth. There are certain circumstances when it might have the initial fertility needed, but it then could drop off. I myself have been using composted manure straight from the bag in some barrel planters this year for certain annual crops, and it does a great job supply them with what they need for about a month, then they start to develop symptoms of N deficiency, so I know its time to fertilize.

I would definitely begin to fertilize regularly with something, whether conventional or organic. Personally, if it were me I would apply something like a 12-12-12 to the bed, water that in well, wait 5-6 days, and then do a couple of follow up shots of Miracle Grow.

You may get some clues from the appearance of the plants. Is the color still dark green, or have they gotten a pale yellowish or even a purple-red cast to them? Those are pretty indicative of poor soil fertility.

It is hard to say whether or not a daily soaking is too much. It all depends on your weather AND the soil structure. If its a loose, sandy, well-drained mix, daily watering could certainly be appropriate if you're in one of the regions of the country where it's been so blazing hot. If the soil is dense and heavy, you certainly could be keeping it too wet, which can cause plants to fail to thrive, but personally after a month I would think you would have seen a few of the most susceptible things develop root rot and die.

So, based on the information presented, I still vote "needs fertilizer".