Repotting guide

When & how to repot Large Bitter-cress (Cardamine amara)

Also called Large Bitter-cress, Large Bittercress.

More about large bitter-cress

About Large Bitter-cress

Cardamine amara · also called Large Bitter-cress, Large Bittercress · edible

Cardamine amara is a native European perennial of the mustard family (Brassicaceae), found along the margins of streams, wet meadows, and alder carr in the UK and across temperate Europe, distinctive for its purple (not white) anthers. It prefers constantly wet, humus-rich soil in partial shade and will not tolerate drought. The leaves have an edible, peppery-bitter watercress-like flavour and can be used raw or cooked, but harvest only from uncontaminated, clean-water sites. No ASPCA data is available for this species; it is classified as mildly-toxic as a precaution since Brassicaceae plants contain glucosinolates that can cause mild gastrointestinal irritation in pets.

Mature size: 30–60 cm tall, 30–40 cm spread

Watch for — Root rot in standing water: Paradoxically, although it is a moisture-lover, prolonged stagnant flooding can rot the crown; flowing or frequently refreshed water is preferred over static boggy conditions.

How to tell large bitter-cress needs repotting

Repotting on a calendar is less reliable than reading the plant. For large bitter-cress, 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 large bitter-cress 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 large bitter-cress

Pot on seedlings as they grow; not a perennial repot. Large Bitter-cressis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Upright to spreading perennial, growing from a creeping rhizome, with pinnate leaves and racemes of small white four-petalled flowers with distinctive purple anthers in April to June..

What size pot to step large bitter-cress up to

Pot large bitter-cress 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 large bitter-cress

Pot large bitter-cress 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 large bitter-cress

Pot on before it is root-bound. Check large bitter-cress 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 wet, humus-rich loam or marginal mud 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 large bitter-cress 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 large bitter-cress

Large Bitter-cress wants wet, humus-rich loam or marginal mud. Thrives in nutrient-rich, water-retentive substrates alongside streams; also grows in standard moist loam enriched with leaf mould or well-rotted compost. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting large bitter-cress — frequently asked questions

How often should you repot large bitter-cress?

Pot on seedlings as they grow; not a perennial repot for large bitter-cress. Large Bitter-cress is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into wet, humus-rich loam or marginal mud 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 large bitter-cress need?

When is the best time of year to repot large bitter-cress?

Can you put large bitter-cress straight into a much bigger pot?

No. Even a fast-growing large bitter-cress 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 large bitter-cress after repotting?

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