i brought a lemon tree from aldi 3 years ago i have lots of green leaves but no flowers why is this ?its about 2ft tall and looks very healthy what do i need to do to make it fruit ?? it is taken in to thee conservatory every year to protect it from the frosts . and taken out side in march and i feed with a good feed, putting it in a sunny area on my patio at the top of the garden next to the green house.