Or they are busy with Heavensward or maybe not active right know. I only now that my old FC always had plants out and most of them where from one or two players.In the end gardening is one point that could be problematic for members there are many more with were written in this thread. It may also depend on your own experience.
if you have no problems with your FC than this might not be so bad. But sadly people can change over time and a FC which was once a happy place can turn bad fast.
And if that happens and you put a lot of work and money into the FC house than it will really hurt to loose it all.