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Plant care

Honesty (Silver dollar plant) care

Lunaria annua

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

RHS H5USDA 5–9Mildly toxic to petsIndoor 60–90 cm tall (2–3 ft)

Watering rhythm

Medium indirect light (a couple of metres from a window)

Twice weekly in dry spells; keep soil consistently moist

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Light

Medium indirect light (a couple of metres from a window)

Soil

Moist, humus-rich, well-drained loam

Humidity

40–70%

Temp

5–20°C

Pet safety

Mildly toxic to pets

Mature size

60–90 cm tall (2–3 ft)

Care at a glance

Light

Honesty wants the spot a few feet back from a sunny window — bright enough to read a paperback at noon, but the sun never falls directly on the leaves. Grows best in partial shade to dappled sunlight, making it ideal under deciduous trees or in north-facing borders. Tolerates full sun if soil moisture is maintained. Shade-tolerance is a key advantage over most flowering annuals and biennials. A faint hand shadow at midday is the right amount; a sharp dark shadow means it's getting direct sun and probably too much.

Watering

Water honesty twice weekly in dry spells; keep soil consistently moist. The actual day count varies with pot size, light, and season — the finger test (or lifting the pot to feel its weight) is more reliable than a fixed calendar. Empty any drainage saucer afterwards so the pot isn't sitting in water. Prefers moist but well-drained soil; avoid waterlogging which causes root rot. Has a long taproot that reaches deep moisture but benefits from supplemental watering during dry springs. Does not tolerate desiccation at the seedling stage.

Soil and pot

Honesty grows best in moist, humus-rich, well-drained loam. Thrives in deep, organically enriched soil. The long taproot means it dislikes compacted or stony ground and does not transplant well once established. A neutral to slightly alkaline pH (6.5–7.5) suits it well. Tolerates most soil types except waterlogged clay. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Honesty sits happiest at around 40–70% humidity and 5–20°C (41–68°F). Adapts to a wide range of ambient humidity typical of temperate climates. No special humidity management required. Good drainage remains more critical than humidity control. If you keep the room above 5–20°C year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed honesty sparingly. 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. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on honesty in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Club root — A Brassicaceae family soil-borne fungal disease causing swollen, distorted roots and wilting. Raise soil pH above 7.0 with lime, avoid growing in the same spot in successive years, and use transplants grown in sterile compost.
  • Slugs and snails — Young seedlings and emerging spring growth are prime targets. Use iron-phosphate pellets, copper tape around raised beds, or evening patrols. Mulch lightly to avoid providing slug habitat.
  • Powdery mildew in dry summers — White coating on leaves in warm, dry conditions exacerbated by poor soil moisture. Maintain consistent watering and improve airflow. Remove affected leaves promptly.

Propagation

Sow seed outdoors in early summer (June–July in the UK) where it is to flower the following spring. Seed germinates readily without stratification. Thin seedlings to 30 cm apart. Plants have long taproots and dislike transplanting once established. Self-seeds prolifically — allow seed pods to shatter naturally for naturalised drifts. Collect ripe pods before they split if controlled spread is preferred. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Honesty is mildly toxic to pets. Lunaria annua belongs to the Brassicaceae family and contains glucosinolates, which can irritate mucous membranes and disrupt thyroid function if ingested in quantity. It is not individually listed on the ASPCA toxic/non-toxic database. Exercise caution around pets that graze on garden plants; ingestion of small amounts is unlikely to cause serious harm but may cause mild gastrointestinal upset. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Honesty care — frequently asked questions

What is the common name for Lunaria annua?

Lunaria annua is most commonly called Honesty, but it is also known as Honesty, Annual honesty, Silver dollar plant, Money plant, Moonwort. The names refer to the same species, so care instructions for Honesty apply identically to anything sold as Silver dollar plant.

How much light does honesty need?

Honesty grows best in medium indirect light (a couple of metres from a window). Grows best in partial shade to dappled sunlight, making it ideal under deciduous trees or in north-facing borders. Tolerates full sun if soil moisture is maintained. Shade-tolerance is a key advantage over most flowering annuals and biennials.

How often should I water honesty?

Water honesty twice weekly in dry spells; keep soil consistently moist. Prefers moist but well-drained soil; avoid waterlogging which causes root rot. Has a long taproot that reaches deep moisture but benefits from supplemental watering during dry springs. Does not tolerate desiccation at the seedling stage. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is honesty toxic to cats and dogs?

Honesty is mildly toxic to pets. Lunaria annua belongs to the Brassicaceae family and contains glucosinolates, which can irritate mucous membranes and disrupt thyroid function if ingested in quantity. It is not individually listed on the ASPCA toxic/non-toxic database. Exercise caution around pets that graze on garden plants; ingestion of small amounts is unlikely to cause serious harm but may cause mild gastrointestinal upset.

What USDA hardiness zone does honesty grow in?

Honesty is rated for USDA zone 5–9 and RHS hardiness H5. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Honesty deep-dive guides

Every aspect of honesty care, each with its own calibrated guide:

Featured in these plant shortlists

Honesty qualifies for 4 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Honesty is also known as Honesty, Annual honesty, Silver dollar plant, Money plant, and Moonwort.