I planted Twist and Shout hydrangeas in large pots on May 5th and they appeared to be doing fine. Then, a few days ago, I noticed that the lower leaves are turning yellow and falling off. According to the last thread on this, my plant needs nitrogen. Should I do that and if so in what form or should I just sit tight and see what happens.

I don't think nitrogen deficiency would necessarily only effect the older, lower leaves. However I do think light, frequent feeding is a good idea for container plants. It sounds to me like they may have dried out too frequently- hydrangeas are sensitive to this.

From what I read yellowing of older leaves is normally over watering or a lack of nitrogen, but to use a fertilizer with no phosphorus. On newer leaves it is most likely a iron deficiency.

I didn't even think of too much water, but I have seen that symptom before. I think I'm so used to hydrangeas being such water hogs it didn't occur to me.

Bob, glad you mentioned that- I've got 2 hydrangeas with yellowing new leaves and adding some soluble nitrogen didn't help. I've used Ironite product in the past and need to get some more.