Hi I have 10 hydrangeas of different types and was looking forward to them blooming in the next few weeks. This morning I noticed 2 of them had wilting stems and browning leaves with the brown spreading from the centre of the stem. I have a horrible feeling that I have poisoned them as I applied a handful of hydrangea feed to each about a week ago, having never used it before. I thought I was following the instructions but it's not looking good. The other 8 plants are (so far!) OK. Both sickly plants are in pots and I have flushed them out twice with a lot of water in case it's too much feed. We've had a lot of hot weather, followed by 2 days of fierce winds this week and a lot of rain. Pictures show a Silver Dollar and in the smaller pot (I think) a Limelight. Any ideas please? Thank you!