Repotting guide

When & how to repot Spearmint 'Kentucky Colonel' (Mentha spicata 'Kentucky Colonel')

Also called Kentucky Colonel mint, julep mint.

More about spearmint 'kentucky colonel'

About Spearmint 'Kentucky Colonel'

Mentha spicata 'Kentucky Colonel' · also called Kentucky Colonel mint, julep mint · herb

'Kentucky Colonel' is a large-leaved spearmint prized for mint juleps, with crinkled bright-green foliage and a sweet, intensely fragrant flavor. A vigorous, spreading perennial, it thrives in moist, rich soil and partial to full sun. Grow it in a pot or sunken bottomless container to contain its aggressive runners, and harvest leaves continuously through the growing season.

Mature size: Typically 30-60 cm tall with an indefinite spread by runners if unconfined.

Watch for — Invasive spreading: Runners colonize beds rapidly; grow in a pot or a bottomless container sunk in the ground to contain it.

How to tell spearmint 'kentucky colonel' needs repotting

Repotting on a calendar is less reliable than reading the plant. For spearmint 'kentucky colonel', 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 spearmint 'kentucky colonel' 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 spearmint 'kentucky colonel'

Pot on seedlings as they grow; not a perennial repot. Spearmint 'Kentucky Colonel'is grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Vigorous, spreading rhizomatous perennial that sends out runners and forms dense clumps; can become invasive if not contained..

What size pot to step spearmint 'kentucky colonel' up to

Pot spearmint 'kentucky colonel' 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 spearmint 'kentucky colonel'

Pot spearmint 'kentucky colonel' 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 spearmint 'kentucky colonel'

Pot on before it is root-bound. Check spearmint 'kentucky colonel' 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 rich, moisture-retentive loam 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 spearmint 'kentucky colonel' 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 spearmint 'kentucky colonel'

Spearmint 'Kentucky Colonel' wants rich, moisture-retentive loam. Fertile, humus-rich soil with good drainage and a near-neutral pH of 6.0-7.5; amend with compost. Mint tolerates damp ground better than most herbs. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting spearmint 'kentucky colonel' — frequently asked questions

How often should you repot spearmint 'kentucky colonel'?

Pot on seedlings as they grow; not a perennial repot for spearmint 'kentucky colonel'. Spearmint 'Kentucky Colonel' is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into rich, moisture-retentive loam 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 spearmint 'kentucky colonel' need?

When is the best time of year to repot spearmint 'kentucky colonel'?

Can you put spearmint 'kentucky colonel' straight into a much bigger pot?

No. Even a fast-growing spearmint 'kentucky colonel' 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 spearmint 'kentucky colonel' after repotting?

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