Getting it to bloom

Why won't my Arum Lily bloom? (and how to make it flower)

Also called Arum Lily, Calla Lily, White Calla, Pig Lily (Zantedeschia aethiopica).

More about arum lily

About Arum Lily

Zantedeschia aethiopica · also called Arum Lily, Calla Lily · flowering

Zantedeschia aethiopica is a robust, rhizomatous perennial native to stream banks, marshes, and moist meadows in southern Africa, producing large, pure-white spathe flowers surrounding a yellow spadix from late winter to early summer. It thrives in moist to wet, humus-rich soil in full sun to part shade and can be grown as a marginal aquatic with roots in shallow water. In the UK it is hardy enough to overwinter outdoors in most areas with mulch protection; in colder climates (USDA zones below 8) lift rhizomes and store frost-free. All parts are toxic to cats and dogs.

Plant type: flowering

Watch for — Botrytis (Grey Mould): Dense, humid conditions in mild wet weather encourage Botrytis cinerea on foliage and flowers; improve air circulation, remove affected material promptly, and avoid overhead watering.

The reasons arum lily isn't blooming

Almost every non-blooming arum lily 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 arum lily 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 arum lily to flower

Maximise sun. Give arum lily 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 arum lily and get the feeding right with the arum lily 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

Arum Lily 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 arum lily care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Arum Lily blooming — frequently asked questions

Why won't my arum lily flower?

Arum Lily 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 arum lily bloom?

Give arum lily 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 arum lily normally bloom?