All For Gardening: I have a new hobby of germinating and growing fruit trees. This is my best so far. A lemon tree that is 4 inches after a little over 6 months. Is this speed of growth average or on the slower side?

I have a new hobby of germinating and growing fruit trees. This is my best so far. A lemon tree that is 4 inches after a little over 6 months. Is this speed of growth average or on the slower side?