Hello Litha welcome to the vine.

Are you sowing them inside ? as it is abviously too early and too cold for certain veggies you mentioned to germinate. How long have you sow them ?
Reckon the mint to be the last to come as it can take months to germinate. Rosemary don't have good germinations rate it is easier to grow them from cutting.
Lemon Balm/mellisa should germinate in within a week to 10 days. cucumber and tomatoes need warmth to germinate.

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