Companion Plants for Fennel

Traditional companions for fennel include head lettuce, leaf lettuce and romaine lettuce.

Keep cherry tomatoes, eggplant and tomatoes away from it.

These are garden traditions, collected from 12 US extension guides. Few have been tested in trials, so treat them as a starting point: spacing, sun and rotation matter more.

Good companions for fennel

Spacing is per square foot, for a raised bed planted square by square. Cool-season companions can share the bed before or after a warm-season crop, or grow in its shade.

Traditional companions for fennel
Plant	Kind	Spacing	Season
Head Lettuce	Vegetable	1 per sq ft	Cool season
Leaf Lettuce	Vegetable	4 per sq ft	Cool season
Romaine Lettuce	Vegetable	1 per sq ft	Cool season

What not to plant with fennel

Cherry Tomatoes: usually planted in a different bed.
Eggplant: usually planted in a different bed.
Tomatoes: usually planted in a different bed.

What the evidence says

Companion planting charts come from long garden experience, and most pairs have never been tried in a replicated trial. Several extension services say so directly; one review gives traditional charts more entertainment than scientific value.

What reliably helps fennel: the right planting dates, enough space, and moving crops to a new bed each year (crop rotation).

Plant them side by side

Draw your beds, tap squares to plant fennel next to their companions, and get every crop's planting dates for your ZIP code. Free, in your browser.

Open the garden planner When to plant fennel

Questions

What can I plant with fennel?

The traditional companions are head lettuce, leaf lettuce and romaine lettuce. Plant companions in neighbouring rows or squares rather than in the same hole.

What should not be planted with fennel?

The guides keep cherry tomatoes, eggplant and tomatoes apart from fennel. Give them a different bed.

Does companion planting with fennel work?

Most pairings are tradition rather than tested results: extension services call companion planting promising but largely unproven. None of the pairs for this crop has been tested in a trial we could find. Good spacing, sun, water and rotation do more for a harvest than any single pairing.

How close can head lettuce grow to fennel?

In a raised bed planted by the square foot, give fennel 1 per sq ft and head lettuce 1 per sq ft, in neighbouring squares. In rows, fennel needs 10 in between plants.