Repotting guide

When & how to repot Threeleaf Arrowhead (Sagittaria trifolia)

Also called Threeleaf Arrowhead, Chinese Arrowroot, Arrowhead Water Plant.

More about threeleaf arrowhead

About Threeleaf Arrowhead

Sagittaria trifolia · also called Threeleaf Arrowhead, Chinese Arrowroot · edible

Sagittaria trifolia is an aquatic perennial native to Asia and parts of the Pacific, widely cultivated in East and Southeast Asia for its starchy, edible corms (called kuwai in Japan and ci gu in China) as well as grown ornamentally in water gardens worldwide. It grows in shallow freshwater margins and paddy fields, producing arrow-shaped leaves and white three-petalled flowers in summer. The single most important care point is keeping the root zone consistently submerged or waterlogged throughout the growing season, even briefly drying out will cause leaf scorch and corm failure. Sagittaria species are considered non-toxic to cats and dogs.

Mature size: Foliage 60–100 cm (24–39 in) tall; individual plant spread 30–60 cm (12–24 in); corms 2–4 cm (0.8–1.6 in) in diameter under good growing conditions.

How to tell threeleaf arrowhead needs repotting

Repotting on a calendar is less reliable than reading the plant. For threeleaf arrowhead, 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 threeleaf arrowhead 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 threeleaf arrowhead

Pot on seedlings as they grow; not a perennial repot. Threeleaf Arrowheadis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Emergent aquatic perennial producing erect arrow-shaped leaves above the water surface, whorled flowers on an upright raceme, and edible starchy corms at the tips of stolons in the sediment..

What size pot to step threeleaf arrowhead up to

Pot threeleaf arrowhead 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 threeleaf arrowhead

Pot threeleaf arrowhead 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 threeleaf arrowhead

Pot on before it is root-bound. Check threeleaf arrowhead 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 heavy loam or alluvial silt; ph 6.0–7.5 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 threeleaf arrowhead 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 threeleaf arrowhead

Threeleaf Arrowhead wants heavy loam or alluvial silt; ph 6.0–7.5. Fertile, fine-grained soils produce the largest corms; amend sandy soils heavily with clay loam and organic matter before planting to improve water retention. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting threeleaf arrowhead — frequently asked questions

How often should you repot threeleaf arrowhead?

Pot on seedlings as they grow; not a perennial repot for threeleaf arrowhead. Threeleaf Arrowhead is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into heavy loam or alluvial silt; ph 6.0–7.5 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 threeleaf arrowhead need?

When is the best time of year to repot threeleaf arrowhead?

Can you put threeleaf arrowhead straight into a much bigger pot?

No. Even a fast-growing threeleaf arrowhead 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 threeleaf arrowhead after repotting?

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