Repotting guide

When & how to repot Mexican Tarragon (Tagetes lucida)

Also called Mexican tarragon, Mexican mint marigold, sweet mace.

More about mexican tarragon

About Mexican Tarragon

Tagetes lucida · also called Mexican tarragon, Mexican mint marigold · herb

Mexican tarragon is a warmth-loving perennial marigold relative grown as an anise-flavoured substitute for French tarragon in hot climates where true tarragon struggles. Native to Mexico and Central America, it forms bushy clumps of glossy leaves topped by small golden-yellow flowers in late summer. It thrives in full sun and heat, tolerates drought, and shrugs off humidity that defeats real tarragon.

Mature size: 45-75 cm tall and 30-45 cm wide

Watch for — Root rot in wet soil: Heavy, waterlogged ground is the main killer. Plant in free-draining soil or raised beds and avoid overwatering, especially in winter.

How to tell mexican tarragon needs repotting

Repotting on a calendar is less reliable than reading the plant. For mexican tarragon, watch for these signs:

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot mexican tarragon on before it becomes hard root-bound.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot mexican tarragon

Pot on seedlings as they grow; not a perennial repot. Mexican Tarragonis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Bushy, upright, clumping tender perennial with erect branching stems and narrow glossy aromatic leaves, crowned in late summer to autumn by clusters of small single golden-yellow daisy flowers..

What size pot to step mexican tarragon up to

Pot mexican tarragon on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot mexican tarragon

Pot mexican tarragon on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting mexican tarragon

Pot on before it is root-bound. Check mexican tarragon regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh light, well-drained, average-fertility soil at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water mexican tarragon in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for mexican tarragon

Mexican Tarragon wants light, well-drained, average-fertility soil. Thrives in free-draining sandy or loamy soil with a near-neutral pH around 6.0-7.5. It actually performs better in lean soil than rich ground, which produces soft leafy growth at the expense of flavour. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting mexican tarragon — frequently asked questions

How often should you repot mexican tarragon?

Pot on seedlings as they grow; not a perennial repot for mexican tarragon. Mexican Tarragon is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into light, well-drained, average-fertility soil so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does mexican tarragon need?

When is the best time of year to repot mexican tarragon?

Can you put mexican tarragon straight into a much bigger pot?

No. Even a fast-growing mexican tarragon should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise mexican tarragon after repotting?

Not immediately. Wait about 1 week after repotting mexican tarragon. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.