I love gardening, but at the moment I'm in a quandary because I planted a sugar khrystal and woke up this morning to rank 7 fire ants!
The problem is, even though I'm almost maxed out at end of gardening level 15, my questing level is in the low 80's and I'm still in Avalon.
Going to Bastion and looking for side quests, I get "Talk to Sylvia Darkside in Mooncliff". This was heartening because she supposedly starts the process for meeting Una Moondancer in Bastion who will then let me meet Barley. However, Sylvia is invisible to me, presumably because I'm not questing in Khrysalis yet.
Do I need to give up gardening until I hit level 90-something?
You don't need to give up gardening. Stick to things that don't have such high needs. You are right about the progression though. I'm not sure why the made the gardener so late in the game.
if you have the "Summon Pixie" spell from the trainer in Kroc, you can use it on your Sugar Khrystal. It only works for the one plant it is cast on, but it will eliminate all pests and keep them from returning for 48 hours.