It is natural for the peas to turn yellow this time of year. They are a cool weather crop and when it heats up the slow down production and start to turn yellow.
As for your cukes I am not sure but you may be overwatering them. Make sure those buckets have enough drainage and stick your finger a few inches in the soil to see if it is dry. The top layer may look it but underneath there may plenty of moisture. They ones I have in large pots have only been getting watered every couple of days because there is enough soil to hold some moisture.
Yes, it does, I am not using mulch either and some of the roots system is showing. I did the finger thing and you are correct. What an elementry solution. Thanks.