大戟

大戟的基本資料

栽培難度

適合中級者

壽命

10+ years

體型

5cm-1m (varies by variety)

適宜溫度

5〜35℃

Sunlight

Loves sunlight. Good ventilation important

Watering

Moderate. Sensitive to overwatering

Soil

Well-draining soil. Add extra pumice

Varieties

Obesa, Horrida, Daimyojin among many popular varieties

Notes

Toxic white latex — avoid skin contact

關於大戟

Euphorbia is one of the largest and most diverse plant genera, with over 2,000 species distributed across Africa, Madagascar, and beyond. Many bear a striking resemblance to cacti—not through shared ancestry, but through convergent evolution in response to arid environments. The genus name honors Euphorbus, physician to an ancient Roman king, reflecting the long history of the plant's potent latex in medicine and as a poison. The visual diversity within the genus is remarkable: the spherical symmetry of E. obesa, the fierce spines of E. horrida, and the candelabra forms of E. lactea all belong to the same family. Their appeal to growers lies in a rewarding simplicity—minimal watering and bright light are all they truly need to maintain sculptural forms for years. Slow-growing and long-lived, Euphorbia rewards patience and offers a genuinely long-term relationship between plant and keeper.

開始照料大戟前需要了解的7件事

1. 1Toxic Latex Warning

   Euphorbias exude a white latex sap when cut or damaged that can cause skin irritation and is harmful if it contacts the eyes. Always wear rubber gloves when pruning or repotting, and wash your hands thoroughly afterward. Keep plants out of reach of pets and small children.

2. 2Water Sparingly

   Euphorbias are drought-tolerant and root rot from overwatering is the most common cause of failure. During the growing season (spring to autumn), water only after the soil has dried out completely; in winter, reduce watering to once a month or less. Never let the pot sit in standing water.

3. 3Provide Plenty of Sunlight

   Euphorbias thrive in bright light and should be placed in the sunniest spot available year-round. A south-facing windowsill is ideal for indoor cultivation; insufficient light leads to etiolation and poor form. In peak summer, use shade cloth if direct midday sun is intense.

4. 4Protect from Cold and Frost

   Most Euphorbias stop growing below 5–10°C and can be damaged or killed by frost. Bring outdoor plants inside before temperatures drop significantly. Cold hardiness varies considerably by species, so confirm the tolerance of your specific variety at the time of purchase.

5. 5Wide Size Variation by Species

   Euphorbias vary enormously in mature size, from compact species just 5 cm across to columnar giants exceeding 1 metre tall. Before buying, check the expected mature size and plan your space and pot size accordingly. The popular Euphorbia obesa stays around 15 cm in diameter, making it well-suited for collections.

6. 6Repot Every 2–3 Years

   When roots become pot-bound, growth slows, so repot into a slightly larger container every two to three years. Do this at the start of the growing season in spring, using a well-draining cactus or succulent mix. Always wear gloves during repotting to avoid contact with the latex sap.

7. 7Fertilise Lightly

   Euphorbias are adapted to nutrient-poor soils, so over-fertilising causes weak, stretched growth and root damage. Apply a dilute balanced fertiliser or slow-release granules once a month during the growing season (spring to summer). Stop feeding from autumn onward to allow the plant to prepare for dormancy.

大戟的常見問題

Q.What should I do if sap gets on my skin?

A.Rinse the affected area immediately and thoroughly with soap and water. If sap enters the eyes, flush with clean water for at least 15 minutes and seek medical attention if irritation persists. The best prevention is to wear gloves and protective eyewear before handling the plant.

Q.How do I tell Euphorbia apart from a cactus?

A.The easiest way is to look at the sap: Euphorbia exudes milky white latex, while cacti produce clear watery sap. Euphorbia spines also tend to grow in pairs, and they lack the distinct areoles—the small cushion-like spots—from which cactus spines emerge.

Q.Can I leave Euphorbia outside in winter?

A.Most Euphorbia species suffer damage below 5°C, so they need to be brought indoors during winter in most parts of Japan. A few cold-hardy species like E. rigida can tolerate light frost, but as a general rule, move plants to a warm, bright indoor location before the first frost to be safe.

Q.Why are the leaves turning yellow and dropping?

A.Overwatering is the most common cause. Watering before the soil fully dries out leads to root rot, which manifests as yellowing and leaf drop. Cold temperatures and insufficient light are the next most frequent culprits. Review your watering schedule and check that the plant is getting adequate warmth and sunlight.

Q.Which Euphorbia varieties are best for beginners?

A.E. obesa, with its charming spherical form, and E. milii (Crown of Thorns), a sturdy columnar type, are commonly recommended for beginners. Both stay compact, grow slowly, and have a reasonable tolerance for minor watering mistakes. They are also widely available and affordably priced, making them great entry points into the genus.

大戟栽培的實用工具

Learn more about 大戟 in the encyclopedia

同分類的更多品種