I think you can use that without worrying: Lemon trees have quite hard leaves. They can take it...

Ok great - good to know, thank you!!!

In summer, the branches and twigs should even be thinned out so that there is enough light in the centre. So I would only arrange low shrubs around the trunk area, if at all...

Oh thank you for this @weisser-rabe! I will definitely do that when the warmer season comes around. As for the shrubs - there is nothing around the bottom of the tree currently, so I think I will just keep it that way and rather opt for other methods to keep the ants off the trunk.

Thank you again for your wisdom xxx