Greetings experienced gardeners!

I planted cucumber starts in a large container, filled with commercial
potting mix (it might have been Miracle Grow potting soil). This is
outside, in a full sun spot in my back yard. The starts did fine for about
2 days, then began to wither up and die. They never even tried to climb up
the cage I provided. Now they are almost dead. The withering started as
the outside of the leaves turned brown, and worked it's way into the rest of
the plant.

Any ideas what might cause this? I've given up hope on these plants, but
want to prevent this from happening again.

TIA, Shannon