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Repotting guide

When & how to repot Redbor Kale (Brassica oleracea var. sabellica 'Redbor')

Also called Redbor kale, red curly kale, ornamental red kale.

More about redbor kale

About Redbor Kale

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

'Redbor' is a tightly curled F1 kale with striking deep magenta-purple, frilly leaves on a tall stem, equally at home in the vegetable plot and the ornamental border. The colour deepens and intensifies in cold weather, and the leaves sweeten after frost. Like all curly kales it is a hardy, heavy-feeding cool-season biennial, very frost-tolerant and at its best from autumn through winter.

Mature size: Typically 60-90 cm tall and 45-60 cm wide, occasionally taller when overwintered.

Watch for — Wind rock: Tall plants on loose soil rock in wind, loosening roots and stunting growth. Plant firmly and deeply, earth up the stem, and stake exposed plants.

How to tell redbor kale needs repotting

Repotting on a calendar is less reliable than reading the plant. For redbor kale, watch for these signs:

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot redbor kale

Pot on seedlings as they grow; not a perennial repot. Redbor Kaleis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Tall, upright, non-heading biennial grown as an annual, with a single stout stem bearing a dense crown of tightly curled leaves; pick lower leaves and it continues to produce from the top..

What size pot to step redbor kale up to

Pot redbor kale on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot redbor kale

Pot redbor kale on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting redbor kale

  1. Pot on before it is root-bound. Check redbor kale regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
  2. Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
  3. Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
  4. Pot into rich mix. Set it into fresh rich, firm, well-drained loam at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
  5. Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water redbor kale in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for redbor kale

Redbor Kale wants rich, firm, well-drained loam. Fertile, organic-rich and moisture-retentive with a firm root run for tall, top-heavy plants. Slightly acidic to neutral pH 6.0-7.5; lime toward neutral to suppress clubroot. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting redbor kale — frequently asked questions

How often should you repot redbor kale?

Pot on seedlings as they grow; not a perennial repot for redbor kale. Redbor Kale is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into rich, firm, well-drained loam so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does redbor kale need?

Pot redbor kale on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check. Use our pot size calculator to size it from the plant's current pot and root spread.

When is the best time of year to repot redbor kale?

Pot redbor kale on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Can you put redbor kale straight into a much bigger pot?

No. Even a fast-growing redbor kale should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise redbor kale after repotting?

Not immediately. Wait about 1 week after repotting redbor kale. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.

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