Q.lobelia
I purchased some lobelia plants about 2 weeks ago and bedded them out the same day. They appeared to become established, but about 1 week ago, one or two of the plants had lost their leaves and over the last week, more of them have lost their leaves. The leaves don’t appear to have dropped off – they have simply disappeared. Are there any obvious possible explanations and, if so, what can be done to save the remainder of the plants?

It is probably either woodchucks, rabbits or deer. For more information on how to keep these animals out of your garden, please visit the following links:
https://www.gardeningknowhow.com/plant-problems/pests/animals/keep-rabbits-out-of-gardens.htm
https://www.gardeningknowhow.com/plant-problems/pests/deer/deer-repellents.htm
http://pss.uvm.edu/ppp/articles/woodchucks.html