Repotting guide
When & how to repot Yarrow (Achillea millefolium)
Also called yarrow, common yarrow, milfoil.
More about yarrow
About Yarrow
Achillea millefolium · also called yarrow, common yarrow · herb
Yarrow is a tough, drought-resistant perennial with finely divided ferny leaves and flat-topped clusters of tiny flowers from summer into autumn. A magnet for pollinators and beneficial insects, it spreads by rhizomes to form weed-suppressing mats. Ideal for dry meadows and gravel gardens, it is toxic to pets and grazing animals if eaten.
Mature size: Typically 0.3-0.9 m tall and spreading 0.45-0.6 m or more by rhizomes.
How to tell yarrow needs repotting
Repotting on a calendar is less reliable than reading the plant. For yarrow, 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 yarrow 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 yarrow
Pot on seedlings as they grow; not a perennial repot. Yarrowis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Rhizomatous, mat-forming herbaceous perennial with upright flowering stems, soft feathery aromatic foliage, and dense flat corymbs of small flowers; spreads steadily to form colonies..
What size pot to step yarrow up to
Pot yarrow 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 yarrow
Pot yarrow 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 yarrow
- Pot on before it is root-bound. Check yarrow 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 lean, free-draining 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 yarrow 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 yarrow
Yarrow wants lean, free-draining soil. Thrives in poor, dry, sandy or gravelly ground across a wide pH range. Rich, moist or heavy soils produce lax growth and worsen its spreading tendency; sharp drainage is best. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.
Repotting yarrow — frequently asked questions
How often should you repot yarrow?
Pot on seedlings as they grow; not a perennial repot for yarrow. Yarrow is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into lean, free-draining 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 yarrow need?
Pot yarrow 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. Use our pot size calculator to size it from the plant's current pot and root spread.
When is the best time of year to repot yarrow?
Pot yarrow 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.
Can you put yarrow straight into a much bigger pot?
No. Even a fast-growing yarrow 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 yarrow after repotting?
Not immediately. Wait about 1 week after repotting yarrow. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.
Related guides
- Yarrow care — light, water, soil and common problems
- How often to water yarrow — the watering brief
- How to repot a plant — the complete step-by-step method
- Root-bound plant — how to spot and fix it
- Pot size calculator — size the next pot correctly
- When & how to repot basil
- When & how to repot herb garden
- When & how to repot mint
- All 2464 repotting guides in the Growli library