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Fertilising guide

How to fertilise Honesty (Lunaria annua)— schedule & NPK

Also called Honesty, Annual honesty, Silver dollar plant, Money plant, Moonwort.

More about honesty

About Honesty

Lunaria annua · also called Honesty, Annual honesty · flowering

A biennial from the Brassicaceae family grown for its vivid purple or white spring flowers and its striking translucent, coin-like seed pods prized in dried arrangements. Tolerates partial shade and self-seeds prolifically. Sow in early summer to flower and pod the following spring.

Growth habit: Biennial; rosette in year one, erect branching stems to 90 cm in year two

What fertiliser honesty actually wants — and why

Honesty 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 honesty: 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 honesty, 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 honesty:

Apply a balanced slow-release granular fertiliser in early spring of the flowering year. Rich soil usually provides sufficient nutrition; avoid high-nitrogen feeds that delay flowering. No autumn feeding is needed in the first year. Treat that as sparingly through the growing season 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 honesty 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 honesty

Half strength is the safe default for honesty — 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 honesty first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the honesty watering schedule.

Signs you are over-feeding honesty

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

Signs you are under-feeding honesty

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

Flushing and leaching the salts

Flush the pot of honesty 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 honesty

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 honesty — frequently asked questions

What fertiliser does honesty 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. Honesty 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 honesty?

Apply a balanced slow-release granular fertiliser in early spring of the flowering year. Rich soil usually provides sufficient nutrition; avoid high-nitrogen feeds that delay flowering. No autumn feeding is needed in the first year. Apply a balanced slow-release granular fertiliser in early spring of the flowering year. Rich soil usually provides sufficient nutrition; avoid high-nitrogen feeds that delay flowering. No autumn feeding is needed in the first year. Treat that as sparingly through the growing season 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 honesty?

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

What does over-feeding honesty 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 honesty 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 honesty?

Flush the pot of honesty 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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