Do I have a green thumb?

While in Japan, I grew some herbs and flowers in my little garden; however, when it comes to citrous fruits, I am wet behind the ears.

This is a lemon tree I took over from the previous tenant of this house who is now a good friend of mine.

I don't know if it's because of either my dedicated watering or San Diego's perfect weather for the plants, but these lemons are growing up easily ^^