Getting it to bloom

Why won't my Greater Sea Kale bloom? (and how to make it flower)

Also called Greater sea kale, Flowering sea kale, Colewort, Giant sea kale (Crambe cordifolia).

More about greater sea kale

About Greater Sea Kale

Crambe cordifolia · also called Greater sea kale, Flowering sea kale · flowering

Crambe cordifolia is a majestic herbaceous perennial native to the Caucasus region and northern Iran, producing enormous dark green, heart-shaped, lobed basal leaves and a spectacular cloud of tiny, fragrant white flowers on branched stems up to 2 m tall in early summer. It thrives in deep, fertile, well-drained neutral to alkaline soil in full sun or partial shade, forming a bold architectural focal point in borders. Young leaves and roots are edible with a cabbage-like flavour, though the plant is primarily grown as an ornamental. No toxicity has been documented for this species in veterinary literature; it is an edible Brassicaceae member, but treat as mildly toxic out of caution as it is not on the ASPCA confirmed non-toxic list.

Plant type: flowering

The reasons greater sea kale isn't blooming

Almost every non-blooming greater sea kale traces back to one of these, roughly in order of how common they are:

Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.
Too much nitrogen feed, driving lush foliage at the expense of flowers (very common with general or lawn feeds).
The plant has not been deadheaded, so it stops flowering once it sets seed.
Irregular watering — drought or waterlogging at the budding stage makes buds abort.
It is still too young or was checked by a transplant and is rebuilding before flowering.

Feeding greater sea kale a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.

The fix — how to get greater sea kale to flower

Maximise sun. Give greater sea kale the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers.
Switch the feed. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.
Deadhead regularly. Remove spent flowers often to keep it producing more rather than stopping to set seed.
Water consistently. Keep moisture even through budding and flowering — drought-then-flood swings make buds drop.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for greater sea kale and get the feeding right with the greater sea kale fertilising schedule — the wrong feed (too much nitrogen) is one of the most common silent reasons a healthy plant makes leaves instead of flowers.

Bloom season and what to expect

Greater Sea Kale flowers across its growing season (mostly summer) and, kept fed and deadheaded, can bloom for many weeks or right up to frost.

Post-bloom care so it flowers again

Deadhead, keep feeding lightly, and many will rebloom; collect seed from the best plants at the end of the season if you want to grow them again.

For everything else this plant needs day to day, see the full greater sea kale care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Greater Sea Kale blooming — frequently asked questions

Why won't my greater sea kale flower?

Greater Sea Kale blooms on the season's growth given enough sun, warmth and the right feed — there is no cold or photoperiod trick, just good growing conditions and a bloom-leaning feed. The most common reason it is not happening: Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.

How do I make greater sea kale bloom?

Give greater sea kale the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.

When does greater sea kale normally bloom?