As per Hinduism and vastu, lemon tree in house is good. The belief is that all kinds of negative energy will not enter the house if there is a lemon tree in the compound or in the balcony of the house.
It is also believed that lemon tree removes all kinds of vastu dosh.
It is believed that negative forces and energy in the universe get attracted to lemon and do not bother to disturb the peace of the house. This is one reason why lemon is hung in front of shops and houses. Bad luck and evil forces will consume the lemon and will leave.