Mature size & growth rate

How big does The King Ostrich Fern (Matteuccia struthiopteris 'The King') get?

Also called The King Ostrich Fern, Ostrich Fern, Shuttlecock Fern.

More about the king ostrich fern

About The King Ostrich Fern

Matteuccia struthiopteris 'The King' · also called The King Ostrich Fern, Ostrich Fern · edible

A large, vigorous cultivar of ostrich fern prized both for its dramatic vase-shaped, bright-green fronds and for its edible fiddleheads — the tightly coiled spring croziers harvested before unfurling. Fiddleheads must be cooked thoroughly before eating. 'The King' forms imposing stands in moist, shaded gardens and spreads by stolons.

Mature size: 120–180 cm tall (4–6 ft), spread 90–150 cm (3–5 ft) per clump; spreads widely via stolons

Watch for — Summer frond browning and collapse: The most common problem, caused by drought or excessive sun. Matteuccia naturally goes partially dormant in hot, dry conditions. Maintain consistent moisture, apply a thick mulch, and position in afternoon shade. Fronds will not recover once browned but new growth returns the following spring.

Indoor size vs how big it gets in the wild

The King Ostrich Fern stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward. Indoors and in a pot, expect 120–180 cm tall (4–6 ft), spread 90–150 cm (3–5 ft) per clump. In the ground with no restriction it is a completely different plant — spreads widely via stolons — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Growth rate and years to mature

The King Ostrich Fern is a fast grower. Realistically, expect two to four years from a young plant to a room-filling specimen in good light. Its feeding profile backs this up: apply a granular balanced fertiliser (e.g. 10-10-10) to the soil in early spring as new croziers emerge. a second application of compost mulch in midsummer maintains soil fertility and moisture. avoid high-nitrogen liquid feeds, which push soft, sappy frond growth.

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

How to keep the king ostrich fern smaller

You are not stuck with the maximum size. For the king ostrich fern specifically, these are the levers, in order of impact:

Divide the clump every year or two — splitting the king ostrich fern is the main way to control its spread and refresh it.
Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump.
Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

The keep-it-smaller method, step by step

Lift the whole plant. Slide the king ostrich fern out of its pot in spring when the clump has filled it.
Split the clump. Tease or cut the rootball into two or more sections, each with healthy roots and growth.
Repot one division. Put a single division back in the original pot to reset it to a smaller size; pot or give away the rest.
Remove offsets as they form. Through the year, detach new runners or pups to stop it spreading again.

How to grow the king ostrich fern bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for the king ostrich fern the accelerators are:

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger.
Brighter light speeds up clump and offset production noticeably.
Leave plantlets and offsets attached and feed through the growing season for the fastest spread.

Light is almost always the ceiling. The the king ostrich fern light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When the king ostrich fern outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for the king ostrich fern:

The clump bulging over the pot rim or splitting the pot — the cue to divide, not to find a bigger room.
A dense centre that goes bare or tired while the edges keep spreading.
Runners or offsets escaping across the shelf or into neighbouring pots.

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

The King Ostrich Fern size — frequently asked questions

How big does the king ostrich fern get?

The King Ostrich Fern reaches 120–180 cm tall (4–6 ft), spread 90–150 cm (3–5 ft) per clump when grown indoors, and far larger where it grows unrestricted (spreads widely via stolons). Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Is the king ostrich fern slow or fast growing?

The King Ostrich Fern is a fast grower. Expect two to four years from a young plant to a room-filling specimen in good light. The King Ostrich Fern stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward.

How long does the king ostrich fern take to reach full size?

Roughly two to four years from a young plant to a room-filling specimen in good light. Light, pot size and feeding move that timeline more than anything else.

How do I keep the king ostrich fern smaller?

Divide the clump every year or two — splitting the king ostrich fern is the main way to control its spread and refresh it. Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump. Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

How can I make the king ostrich fern grow bigger or faster?

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger. Brighter light speeds up clump and offset production noticeably. Leave plantlets and offsets attached and feed through the growing season for the fastest spread.