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Plant care

Ploughman's Spikenard care

Inula conyzae

Also called Ploughman's Spikenard.

RHS H6USDA 5-9Mildly toxic to petsIndoor Up to 130 cm (4 ft 3 in) tall by 40 cm (1 ft 4 in) wide at flowering.

Watering rhythm

2-3weeks

Low — water every 2–3 weeks in dry spells once established

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Light

Direct sun (at least 4-6 hours)

Soil

Well-drained chalk, limestone, or sandy loam; alkaline to neutral pH

Humidity

Low to ambient (30–55% RH)

Temp

-20°C to 25°C

Pet safety

Mildly toxic to pets

Mature size

Up to 130 cm (4 ft 3 in) tall by 40 cm (1 ft 4 in) wide at flowering.

Care at a glance

Light

Most houseplants will scorch where ploughman's spikenard thrives. Give it the windowsill you'd otherwise leave empty because everything else burned there. Requires full sun for at least 6–8 hours per day; will not flower well or persist in shaded positions. A plant moved abruptly from low light to direct sun bleaches in 48 hours — always acclimatise over a week.

Watering

Aim for low — water every 2–3 weeks in dry spells once established for ploughman's spikenard, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Extremely drought-tolerant once established on its preferred chalk or limestone soils; avoid overhead watering and never allow the root zone to become waterlogged.

Soil and pot

Ploughman's Spikenard grows best in well-drained chalk, limestone, or sandy loam; alkaline to neutral ph. Thrives in nutrient-poor, alkaline soils — rich, heavy or moisture-retentive substrates cause lush but floppy growth and reduce longevity. 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

Ploughman's Spikenard sits happiest at around Low to ambient (30–55% RH) humidity and -20°C to 25°C (-4°F to 77°F). A plant of open, airy downland habitats; good air circulation around the stems reduces fungal risk on the hairy foliage. If you keep the room above 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 ploughman's spikenard sparingly. No feeding required; this species thrives on nutrient-poor soils and fertilising encourages rank, unstable growth at the expense of flowering. 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 ploughman's spikenard in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Root rot in heavy or wet soils — The taproot rots rapidly in poorly drained or clay-dominant soils; plant only into gritty, free-draining substrates and avoid planting in low-lying ground that holds winter moisture.
  • Failure to self-seed — As a biennial it relies on setting viable seed to persist; avoid deadheading and leave flowerheads intact through autumn so seeds can disperse onto bare soil nearby.

Propagation

Sow fresh seed in autumn directly onto a prepared bare-soil seedbed, or sow into pots in a cold frame in autumn for transplanting the following spring; seeds need a cold period to break dormancy. 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

Ploughman's Spikenard is mildly toxic to pets. Inula conyzae is not specifically listed on the ASPCA Toxic & Non-Toxic Plant database. Sesquiterpene lactones present in many Asteraceae members can cause contact dermatitis and mild gastrointestinal upset if ingested; classified as mildly-toxic as a precaution rather than confirmed safety. 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.

Ploughman's Spikenard care — frequently asked questions

What is Ploughman's Spikenard?

Ploughman's Spikenard (Inula conyzae) is a flowering plant with a erect biennial or short-lived perennial forming an overwintering basal rosette, sending up tall, branching, purplish flowering stems in year two. growth habit, reaching up to 130 cm (4 ft 3 in) tall by 40 cm (1 ft 4 in) wide at flowering. at maturity. Ploughman's Spikenard is a native British biennial or short-lived perennial in the Asteraceae family, found on dry, calcareous grassland, scrub edges, and chalk downland across England and Wales. It thrives in free-draining alkaline soils in full sun and is best treated as a self-seeding wildflower rather than a formal garden plant; the most important care requirement is sharp drainage, as it will rot in waterlogged conditions.

How much light does ploughman's spikenard need?

Ploughman's Spikenard grows best in direct sun (at least 4-6 hours). Requires full sun for at least 6–8 hours per day; will not flower well or persist in shaded positions.

How often should I water ploughman's spikenard?

Water ploughman's spikenard low — water every 2–3 weeks in dry spells once established. Extremely drought-tolerant once established on its preferred chalk or limestone soils; avoid overhead watering and never allow the root zone to become waterlogged. 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 ploughman's spikenard toxic to cats and dogs?

Ploughman's Spikenard is mildly toxic to pets. Inula conyzae is not specifically listed on the ASPCA Toxic & Non-Toxic Plant database. Sesquiterpene lactones present in many Asteraceae members can cause contact dermatitis and mild gastrointestinal upset if ingested; classified as mildly-toxic as a precaution rather than confirmed safety.

What USDA hardiness zone does ploughman's spikenard grow in?

Ploughman's Spikenard is rated for USDA zone 5-9 and RHS hardiness H6. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Ploughman's Spikenard deep-dive guides

Every aspect of ploughman's spikenard care, each with its own calibrated guide:

Featured in these plant shortlists

Ploughman's Spikenard qualifies for 3 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Ploughman's Spikenard is also commonly called Ploughman's Spikenard.