Sea Wormwood (Old Warrior) care

Light

Aim for at least 4-6 hours of direct sun on the leaves. Full sun is essential. In its wild habitat it grows on open shingle, salt flats, and sea cliffs with no shade. Shade produces weak, open growth and reduced silvering of the foliage. If your only bright window faces south, that's perfect for sea wormwood — same window any aroid would fry on.

Watering

Watering sea wormwood: every 3–4 weeks; extremely drought-tolerant once established. The number that matters isn't the day of the week — it's how dry the top 2-3 cm of the pot feels. A finger in the soil tells you more than a watering app. After every watering, tip the saucer. Highly adapted to dry, saline, coastal conditions. Allow soil to dry between waterings. Waterlogged or heavy soil causes rapid decline. In coastal gardens, established plants rarely need watering beyond natural rainfall.

Soil and pot

Sea Wormwood grows best in sandy, saline-tolerant, very sharply drained. Thrives in poor, sandy, or gravelly soils including saline coastal substrates. Prefers dry, nutrient-poor conditions. Neutral to alkaline pH (6.5–8.5). Completely intolerant of wet, clay, or compacted soils. 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

Sea Wormwood sits happiest at around Low to moderate (25–55% RH) humidity and -20°C to 35°C (-4°F to 95°F). Well adapted to maritime salt-laden air. Tolerates wind and coastal spray. Ensure good airflow to prevent fungal problems in calmer, more humid inland settings. 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 sea wormwood sparingly. Very little fertiliser required or beneficial. A light application of low-nitrogen, balanced feed in spring is the maximum needed. Avoid fertilising in autumn. Lean conditions maintain compact habit. 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 sea wormwood in the Growli community. Each is annotated with the most common cause so you know where to start.

• Root rot in clay or wet soils — This coastal species requires near-perfect drainage. Inland planting in heavy soils almost always results in failure. Use raised beds with a grit and sand mix for inland trials.
• Leggy growth — Without annual trimming, plants become open and woody at the base. Clip by one-third in early spring before new growth and again lightly after flowering to keep a neat dome.
• Spider mite in hot, dry conditions — Despite liking dry conditions, the fine foliage can host spider mites in hot summers. Mist foliage with water in the evening during extreme heat; avoid indoor overwintering in low-humidity rooms.

Propagation

Take 8–10 cm softwood or semi-ripe cuttings in late spring to midsummer; root in gritty, free-draining compost. Division in spring is possible but plants often resent root disturbance. Sow seed on the surface of moist, sandy compost at 15–18°C. 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

Sea Wormwood is mildly toxic to pets. Artemisia maritima is not individually listed by the ASPCA. The plant contains santonin (historically used as an anthelmintic) and volatile oils including thujone — compounds that are toxic in quantity. The ASPCA classifies tarragon (Artemisia dracunculus) as toxic to cats, dogs, and horses. Treat A. maritima as mildly toxic by genus association. Historically a medicinal herb; ingestion of large quantities causes GI upset and neurological effects in animals. 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.

Sea Wormwood deep-dive guides

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

• Common sea wormwood problems & fixes
• Sea Wormwood watering schedule
• Sea Wormwood light requirements
• Best soil mix for sea wormwood
• Sea Wormwood fertilizing guide
• When to repot sea wormwood
• How to propagate sea wormwood
• How to prune sea wormwood
• What's eating my sea wormwood?
• Sea Wormwood growth rate & size
• Sea Wormwood cold hardiness
• Sea Wormwood temperature & humidity
• Is sea wormwood toxic to cats & dogs?
• Is sea wormwood toxic to cats?
• Is sea wormwood toxic to dogs?
• All 15 Artemisia varieties

Related guides

Sea Wormwood is also known as Sea Wormwood, Old Warrior, and Seriphium.

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