The Worst Herb Pairings: 7 Herbs You Should Never Grow Side By Side

Fortunately but also unfortunately, dill and carrots belong to the same family and can often cross-pollinate, which negatively affects both their flavor and growth. Therefore, it isn’t the best idea to pair these two together in the garden.
Ideally, you want to plant dill away from carrots but near cucumbers so they offer their pest-repellent properties effectively.
3: Basil & Sage
As much as I love both these herbs and actually have tried pairing them together in my garden (it didn’t go so well), they both just have different requirements and thrive in substantially different conditions. Basil prefers moist soil, while sage shines in drier conditions, making them poor companions.
A better idea would be to grow basil near tomatoes and sage near rosemary or lavender instead.
4: Fennel & Almost Everything
Yeah…fennel is just one of those herbs I guess…
Trust me, I thought I could find an exception to this rule, some herb, bush, or vegetable plant that would thrive in the company of fennel. But, unfortunately, fennel is just like that one kid at school who nobody wants to play with. It releases certain chemicals that stunt the growth of most nearby plants, including other herbs.
Grow fennel in a completely separate pot or at least away from other herbs if you want to.
5: Rosemary & Basil