Mature size & growth rate

How big does Bishop's flower (Ammi majus) get?

Also called Bishop's flower, false Queen Anne's lace, laceflower, bullwort.

More about bishop's flower

About Bishop's flower

Ammi majus · also called Bishop's flower, false Queen Anne's lace · flowering

Bishop's flower is a tall, airy annual in the carrot family, bearing large flat-topped umbels of delicate white flowers beloved by florists and pollinators alike. It naturalises beautifully in cottage borders and cutting gardens, blooming from early summer into autumn. Sow in situ; it resents root disturbance and self-seeds prolifically.

Mature size: 90–120 cm tall, 30–45 cm spread

Watch for — Flopping in wind: Tall stems are vulnerable to wind damage; plants in exposed positions may need staking with pea sticks or thin canes at around 50 cm height. Alternatively, sow more densely so plants support each other.

Indoor size vs how big it gets in the wild

Bishop's flower reaches its full size within one growing season — there is no "long-term" size, just how big it gets before you harvest or it dies back. Indoors and in a pot, expect 90–120 cm tall, 30–45 cm spread. A pot, your light levels and a little pruning are what set the final size in a home, far more than the plant's theoretical potential.

It sizes up fast and once, racing from seedling to full size in a single season; after cropping it is finished, so size is a within-season question.

Growth rate and years to mature

Bishop's flower is a moderate grower. Realistically, expect a single growing season — it reaches full size in one year, then is done. Its feeding profile backs this up: incorporate a balanced granular fertiliser into the bed before sowing. on fertile soils, no further feeding is usually required. on poor soils, apply a balanced liquid feed monthly during the growing season. avoid high nitrogen, which promotes leafy growth over flowers.

Want this turned into the right next pot at the right moment? The pot size calculator and the bishop's flower repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast bishop's flower grows.

How to keep bishop's flower smaller

You are not stuck with the maximum size. For bishop's flower specifically, these are the levers, in order of impact:

Choose a compact or dwarf variety of bishop's flower from the start — that is the most reliable size control for an annual.
Grow it in a smaller container to naturally limit how large it gets.
For some crops, pinching or pruning the growing tips keeps the plant shorter and bushier.
Sow a little later or space plants closer if you specifically want smaller individual plants.

How to grow bishop's flower bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for bishop's flower the accelerators are:

Full sun, warm soil and steady water are what drive a crop to full size fastest.
Sow at the right time for your zone so it gets the whole season to size up.
Feed appropriately for the crop and never let it check (stall) from drought or cold.

Light is almost always the ceiling. The bishop's flower light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When bishop's flower outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for bishop's flower:

It sprawls beyond its bed or container before harvest — usually a spacing or support issue.
It flops or needs staking once it hits full height.
Once it has fruited or bolted, it is at its final size for good — the next plant is a new sowing.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the bishop's flower repotting guide. If you want more of this plant instead of a bigger one, the bishop's flower propagation guide turns prunings into new plants.

Bishop's flower size — frequently asked questions

How big does bishop's flower get?

Bishop's flower reaches 90–120 cm tall, 30–45 cm spread when grown indoors. It sizes up fast and once, racing from seedling to full size in a single season; after cropping it is finished, so size is a within-season question.

Is bishop's flower slow or fast growing?

Bishop's flower is a moderate grower. Expect a single growing season — it reaches full size in one year, then is done. Bishop's flower reaches its full size within one growing season — there is no "long-term" size, just how big it gets before you harvest or it dies back.

How long does bishop's flower take to reach full size?

Roughly a single growing season — it reaches full size in one year, then is done. Light, pot size and feeding move that timeline more than anything else.

How do I keep bishop's flower smaller?

Choose a compact or dwarf variety of bishop's flower from the start — that is the most reliable size control for an annual. Grow it in a smaller container to naturally limit how large it gets. For some crops, pinching or pruning the growing tips keeps the plant shorter and bushier. Sow a little later or space plants closer if you specifically want smaller individual plants.

How can I make bishop's flower grow bigger or faster?

Full sun, warm soil and steady water are what drive a crop to full size fastest. Sow at the right time for your zone so it gets the whole season to size up. Feed appropriately for the crop and never let it check (stall) from drought or cold.