Mel's mix is a square foot gardening thing correct? I am not familiar with it.

I think it is odd that they leaves die as a result of rain. I suspect something else is the problem. I think photos would help a lot.

Could you go into more detail about your leaves dying? Are all of the leaves wilting or are they actually dying off? Is it all the leaves or just the outermost leaves?

Maybe it could be over-watering. Is there any reason the drainage could be worse by the affected plant that might cause the plant to sit in water. If I remember your setup correctly do you have a liner or anything under the plants in that raised bed and is that plant on the low end of the garden?

Thanks for responding Trev, you are one of this forum's greatest assets. You are correct, the mel's mix is a sfg thing, that I must admit - works very well, and I do have a liner in the bottom. I will go into further detail about the leaves dying. The first time it happened, was after we got 6-8" of rain in 3 days. That time, the outer edge of the largest, exterior leaves got a light color to them, and eventually turned entirely brown - then died. So, I cut back on watering them a bit, and the new leaves came in and everything turned lush again. Now, everything has looked great, until it rained about 1" last Saturday. Since then, the largest, outer leaves have large brown spots or splotches on them. I expect these to die as well. One thing about my bed, that you have me thinking about, from your questions.....the site that it was built on was of course - not level, and there are some differences in the depths from one end to the other. The depth at the end where the yellow squash are is appr. 8-10", and the depth at the end where the zucs are is appr. 6-8" . Meaning, the end where the yellow squash is located has more area for the water to drain....Hmmmm..that may be it. One thing is for sure, next year - because of crop rotation reasons - i'm going to plant the exact same vegetables in there, except switch ends with everything. That will tell me for sure. I'll try to get some pics for ya this weekend.

I agree with Trev's assessment. While there is great variance among cultivars, generally zucchini s are larger plants with deeper root systems. It does sound like the roots are standing in water for several hours after a rain. The liner is probably giving you a swimming pool effect. You may want to consider adding low side drains at the downhill end.

Thanks FD - I think i'm going to investigate further, when the current crop is finished producing - and I can expose the bottom of the bed in that area. I should be able to rake the mel's mix back with my hands, and not damage the liner/fabric. Then allow for more drainage under that section by digging some small trenches in the existing earth under the bed. Here's a pic of the zucchini this evening.Thanks again for your input, FD.

Just a thought, but I have found that celery does exceptionally well in the boggiest part of my SFG.

I don't have alot of experience with zucchini/squash but.... it might help to poke a few holes through the liner with a pitchfork or something on the lower end for drainage.