Hello Gavirz. As you say your lemon tree is potted it is probably best not to plant anything in the same pot as the plants will compete for water and nutrients.
Cacoethes: An irresistible urge to do something inadvisable
Most of these would be better planted nearby rather than in the pot, as Ladybird4 says, they will compete too much with the lemon and plants like fennel and borage would quickly swamp it. I would think you could safely plant a few marigolds (tagetes) in the pot if there is room, the chemicals released from the roots as well as the smell of the flowers combine to form a good pest repellent.
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Most of these would be better planted nearby rather than in the pot, as Ladybird4 says, they will compete too much with the lemon and plants like fennel and borage would quickly swamp it. I would think you could safely plant a few marigolds (tagetes) in the pot if there is room, the chemicals released from the roots as well as the smell of the flowers combine to form a good pest repellent.