Hello all, I just started growing fruit trees at the end of last summer so I'm trying to teach myself on the fly and from what I can research on my own.

I have a strawberry guava that I got from lowes and it was flowing towards the end of summer last year and just start flowing again....flowers just fell off....again. I've been trying to hand pollinate it since my yard has had no pollinators as of yet. Is the tree likely to young? is it to cold ? just kind of lost since I feel like im doing everything right. Im in the SF bay area, so far its been cold(in my opinion) 50s day 40s night