Mature size & growth rate

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

Also called Scarlet kale, red kale.

More about scarlet kale

About Scarlet Kale

Brassica oleracea var. sabellica 'Scarlet' · also called Scarlet kale, red kale · edible

'Scarlet' is a curly kale with finely frilled leaves that turn from green to vivid purple-red as cold weather sets in, making it both a winter vegetable and an ornamental. The colour deepens with frost and the leaves grow sweeter and more tender after a cold snap. It is a very hardy, heavy-feeding cool-season biennial grown as an annual, productive from autumn through winter.

Mature size: Typically 50-80 cm tall and 45-60 cm wide.

Watch for — Clubroot: Stunting and wilting with swollen, distorted roots in infected soil. Rotate brassicas, raise pH toward neutral with lime, and improve drainage; spores persist for years.

Indoor size vs how big it gets in the wild

Scarlet 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 typically 50-80 cm tall and 45-60 cm wide.. 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

Scarlet 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: hungry for nitrogen. incorporate compost or aged manure before planting and side-dress or liquid-feed with a nitrogen-rich fertiliser every 3-4 weeks to sustain leafy growth and deep colour.

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

How to keep scarlet kale smaller

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

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

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

When scarlet kale outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for scarlet 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 scarlet kale repotting guide. If you want more of this plant instead of a bigger one, the scarlet kale propagation guide turns prunings into new plants.

Scarlet Kale size — frequently asked questions

How big does scarlet kale get?

Scarlet Kale reaches typically 50-80 cm tall and 45-60 cm wide. 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 scarlet kale slow or fast growing?

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

Choose a compact or dwarf variety of scarlet 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 scarlet 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.