Repotting guide

When & how to repot Toothpick plant (Ammi visnaga)

Also called Toothpick plant, toothpick weed, khella, greater Bishop's flower.

More about toothpick plant

About Toothpick plant

Ammi visnaga · also called Toothpick plant, toothpick weed · flowering

Toothpick plant is a robust, stiffly upright umbellifer grown for its exceptionally large, domed white flower heads that dry to stiff, ivory-green 'toothpick' fruiting umbels prized in dried arrangements. Flowers from midsummer to autumn on strong, tall stems. Easier than Ammi majus in heat and more bolt-resistant in warm climates.

Mature size: 90–150 cm tall, 30–45 cm spread

Watch for — Slow germination in cold soil: Seeds germinate poorly below 13°C. Sowing too early in cold soil leads to patchy, delayed stands. Wait until soil has warmed, or start indoors at 18–21°C in paper pots to avoid root disturbance at transplanting.

How to tell toothpick plant needs repotting

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

Pot on seedlings as they grow; not a perennial repot. Toothpick plantis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Stiffly upright annual umbellifer.

What size pot to step toothpick plant up to

Pot toothpick plant 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 toothpick plant

Pot toothpick plant 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 toothpick plant

Pot on before it is root-bound. Check toothpick plant 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 well-drained, moderately fertile sandy or loamy 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 toothpick plant 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 toothpick plant

Toothpick plant wants well-drained, moderately fertile sandy or loamy soil. Tolerates relatively poor, dry soil better than many garden annuals, pH 6.0–8.0. Excessively rich soil produces large plants with weaker stems prone to lodging. A lean, well-drained Mediterranean-type soil produces the strongest, most architecturally upright specimens. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting toothpick plant — frequently asked questions

How often should you repot toothpick plant?

Pot on seedlings as they grow; not a perennial repot for toothpick plant. Toothpick plant is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into well-drained, moderately fertile sandy or loamy 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 toothpick plant need?

When is the best time of year to repot toothpick plant?

Can you put toothpick plant straight into a much bigger pot?

No. Even a fast-growing toothpick plant 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 toothpick plant after repotting?

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