Lemons resonate with the energy of the moon and the element of water and can be used to celebrate lunar deities and lemonade is especially good for summertime rituals. In hoodoo a lemon can be used to sour & shut someone up. Take a whole lemon scoop out the inside and stuff it full of the personal concerns from your intended target. Sew or pin the lemon shut with nine needles or pins and then let it shrivel or stick it into a freezer to sour & shut their mouth of the lies they are speaking.
Lemon juice is purifying and cleansing and can be used to that capacity in ritual, try using it as an asperge or using lemon bath products in your ritual bath. A lemon leaf or piece can be added to bath tea for the same purpose or even be added to wash water to cleanse your home. It is also said it can be used in love spells and the rind can be added to baked goods prepared with loving intent.
The fruit can be used to turn away harmful spells or the evil eye.