Mature size & growth rate

How big does Kale (Brassica oleracea var. sabellica) get?

Also called curly kale, Tuscan kale, cavolo nero, Lacinato kale.

About Kale

Brassica oleracea var. sabellica · also called curly kale, Tuscan kale · edible

Kale is a cold-hardy leafy brassica that crops from late summer through deep winter and into the following spring. Frost sweetens the leaves. Pair with brassica-friendly companions and protect from cabbage white butterflies. Toxic to pets in large amounts.

Kale is the non-heading (Acephala Group) form of Brassica oleracea, the same species as cabbage and broccoli, derived from wild cabbage of the eastern Mediterranean and Asia Minor and grown as a leafy crop since Greek and Roman times.

A hardy biennial grown as an annual that forms a loose leafy rosette rather than a head, tolerates frost down to roughly 25 F, and turns noticeably sweeter after a hard frost converts starches to sugars.

Mature size: 60-90 cm tall

Sources: gardens.duke.edu, plants.ces.ncsu.edu, pmc.ncbi.nlm.nih.gov

Indoor size vs how big it gets in the wild

Kale 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 60-90 cm tall. 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

Kale 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 balanced feed at planting; top-dress with nitrogen every 6 weeks during heavy harvesting.

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

How to keep kale smaller

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

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

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

When kale outgrows the room (or the pot)

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

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

Kale size — frequently asked questions

How big does kale get?

Kale reaches 60-90 cm tall 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 kale slow or fast growing?

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

Choose a compact or dwarf variety of kale 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 kale 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.