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Fertilising guide

How to fertilise Zantedeschia 'Picasso' (Zantedeschia 'Picasso')— schedule & NPK

Also called Picasso calla lily, purple-edged calla.

More about zantedeschia 'picasso'

About Zantedeschia 'Picasso'

Zantedeschia 'Picasso' · also called Picasso calla lily, purple-edged calla · flowering

Zantedeschia 'Picasso' is a striking hybrid calla lily with two-tone spathes: creamy white flushed with deep violet-purple toward the throat and edges. Its dark green leaves are often silver-spotted. Grown from rhizomes, it flowers in summer in pots and borders, wanting bright indirect light, moist free-draining soil, and a dry winter rest at about 40-50 cm.

Growth habit: Clump-forming rhizomatous perennial with upright, spotted arrow-shaped leaves and erect stems each carrying one bicoloured spathe.

Watch for — Botrytis on spathes: Pale areas are prone to grey mould if water sits on them; water at the base and improve air circulation.

What fertiliser zantedeschia 'picasso' actually wants — and why

Zantedeschia 'Picasso' is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.

A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for zantedeschia 'picasso': match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed zantedeschia 'picasso', and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For zantedeschia 'picasso':

Feed with a high-potassium liquid fertiliser every 2-3 weeks in active growth to support flowering and crisp spathe colour. Limit high-nitrogen feeds, which favour leaves. Stop feeding when the foliage begins to die back. Treat that as every 2-3 weeks between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.

The dormant-season rule matters more than the exact interval: skip feeding entirely when zantedeschia 'picasso' is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for zantedeschia 'picasso'

Half strength is the safe default for zantedeschia 'picasso' — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

Feeding always goes onto already-damp soil, never dry roots — water zantedeschia 'picasso' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the zantedeschia 'picasso' watering schedule.

Signs you are over-feeding zantedeschia 'picasso'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for zantedeschia 'picasso':

Signs you are under-feeding zantedeschia 'picasso'

If the symptoms point at watering, light or roots rather than nutrition, the full zantedeschia 'picasso' care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush the pot of zantedeschia 'picasso' with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.

Organic vs synthetic feeds for zantedeschia 'picasso'

Organic options

A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.

Synthetic / liquid feeds

A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising zantedeschia 'picasso' — frequently asked questions

What fertiliser does zantedeschia 'picasso' need?

A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Zantedeschia 'Picasso' is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.

How often should I feed zantedeschia 'picasso'?

Feed with a high-potassium liquid fertiliser every 2-3 weeks in active growth to support flowering and crisp spathe colour. Limit high-nitrogen feeds, which favour leaves. Stop feeding when the foliage begins to die back. Feed with a high-potassium liquid fertiliser every 2-3 weeks in active growth to support flowering and crisp spathe colour. Limit high-nitrogen feeds, which favour leaves. Stop feeding when the foliage begins to die back. Treat that as every 2-3 weeks between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.

What strength of feed for zantedeschia 'picasso'?

Half strength is the safe default for zantedeschia 'picasso' — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.

What does over-feeding zantedeschia 'picasso' look like?

Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding zantedeschia 'picasso' year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.

Should I flush the soil of zantedeschia 'picasso'?

Flush the pot of zantedeschia 'picasso' with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.

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