Mature size & growth rate

How big does Tatsoi (Brassica rapa var. narinosa) get?

Also called tatsoi, spinach mustard, rosette bok choy.

More about tatsoi

About Tatsoi

Brassica rapa var. narinosa · also called tatsoi, spinach mustard · edible

Tatsoi forms a low, flat rosette of spoon-shaped, glossy dark green leaves with a mild, mustardy-spinach flavour. One of the most cold-hardy Asian greens, it sweetens after frost and can crop into winter under cover. Quick from seed and excellent as baby leaf or full rosettes, it shines in salads, soups, and quick stir-fries.

Mature size: About 15-25 cm (6-10 inches) across and 10-20 cm (4-8 inches) tall; cut as baby leaf much smaller.

Watch for — Flea beetles: Shothole the leaves and stunt seedlings, the most common pest. Grow under fine mesh from sowing and keep plants moist and vigorous.

Indoor size vs how big it gets in the wild

Tatsoi 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 about 15-25 cm (6-10 inches) across and 10-20 cm (4-8 inches) tall. In the ground with no restriction it is a completely different plant — cut as baby leaf much smaller. — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

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

Tatsoi is a fast grower. Realistically, expect a single growing season — it reaches full size in one year, then is done. Its feeding profile backs this up: a modest leaf feeder. compost worked into the bed usually suffices; a dilute balanced or nitrogen-rich liquid feed every 2-3 weeks supports fast cut-and-come-again growth.

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

How to keep tatsoi smaller

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

Choose a compact or dwarf variety of tatsoi 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 tatsoi bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for tatsoi 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 tatsoi light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When tatsoi outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for tatsoi:

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 tatsoi repotting guide. If you want more of this plant instead of a bigger one, the tatsoi propagation guide turns prunings into new plants.

Tatsoi size — frequently asked questions

How big does tatsoi get?

Tatsoi reaches about 15-25 cm (6-10 inches) across and 10-20 cm (4-8 inches) tall when grown indoors, and far larger where it grows unrestricted (cut as baby leaf much smaller.). 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 tatsoi slow or fast growing?

Tatsoi is a fast grower. Expect a single growing season — it reaches full size in one year, then is done. Tatsoi 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 tatsoi 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 tatsoi smaller?

Choose a compact or dwarf variety of tatsoi 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 tatsoi 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.