Repotting guide

When & how to repot Nasturtium officinale (Nasturtium officinale)

Also called Watercress, Common Watercress, Water Nasturtium.

More about nasturtium officinale

About Nasturtium officinale

Nasturtium officinale · also called Watercress, Common Watercress · edible

Nasturtium officinale is watercress, a fast-growing peppery salad green in the cabbage family that thrives in cool, clean, flowing freshwater. It forms trailing stems of round leaves that root readily at every node, making it easy to grow in shallow streams, troughs or even a sunny windowsill jar. Home-grown cress avoids the contamination risk of wild stands.

Mature size: Stems trail 30-60 cm and root as they spread, forming mats that can cover a square metre or more of wet ground.

How to tell nasturtium officinale needs repotting

Repotting on a calendar is less reliable than reading the plant. For nasturtium officinale, 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 nasturtium officinale 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 nasturtium officinale

Pot on seedlings as they grow; not a perennial repot. Nasturtium officinaleis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Low, sprawling aquatic perennial herb with hollow trailing stems that root at the nodes, forming dense spreading mats of round, peppery leaves in and along water..

What size pot to step nasturtium officinale up to

Pot nasturtium officinale 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 nasturtium officinale

Pot nasturtium officinale 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 nasturtium officinale

Pot on before it is root-bound. Check nasturtium officinale 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, moist, neutral-to-alkaline loam kept saturated 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 nasturtium officinale 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 nasturtium officinale

Nasturtium officinale wants rich, moist, neutral-to-alkaline loam kept saturated. Prefers fertile, water-retentive loam high in organic matter, ideally slightly alkaline (pH around 6.5-7.5). A heavy compost-rich mix in a pot standing in water mimics its streamside habitat; pure aquatic culture in clean water also works. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting nasturtium officinale — frequently asked questions

How often should you repot nasturtium officinale?

Pot on seedlings as they grow; not a perennial repot for nasturtium officinale. Nasturtium officinale is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into rich, moist, neutral-to-alkaline loam kept saturated 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 nasturtium officinale need?

When is the best time of year to repot nasturtium officinale?

Can you put nasturtium officinale straight into a much bigger pot?

No. Even a fast-growing nasturtium officinale 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 nasturtium officinale after repotting?

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