Here's a fun fact for you: Slugs LOVE Parsley, but leave Lemon Balm untouched. This morning I have attempted the rescue of 40 parsley seedlings. Their cotyledon have been badly mauled, but despite this their first true leaves were emerging. So I pricked them out into modules.

I've balanced the module tray on a big tin cup in a tray of water to frustrate the slugs and give the seedlings a chance of recovering. 

In front of them are lemon balm, also showing first true leaves, but nevertheless still tiny. Big enough to be pricked out this weekend. I want a lot of them, a patch 12x6ft, so 80 plants. It's a genuine therapeutic herb: Scholar gives almost 3000 hits of mentions of Melissa officinalis since 2018. We'll mostly use it for tea.