Welsh onion care guide
Allium fistulosum
Also known as: Japanese bunching onion, Green onion, Scallion
Pets and children
Considered toxic
All parts contain compounds that destroy red blood cells in dogs and cats, even when cooked, and anemia, dark urine, and weakness can appear days later; keep it out of reach and consult a veterinarian right away if any is eaten.
How often to water Welsh onion
- Spring–Summer (Mar–Sep)
- Every 3 days
- It dislikes wet soil, so as a guide water after the topsoil has dried; potted plants dry fast in midsummer, so check in the morning.
- Autumn (Oct–Nov)
- Every 4 days
- It grows well in the cool; as a guide, water about one to two days after the topsoil dries.
- Winter (Dec–Feb)
- Every 7 days
- Growth nearly stops, so water sparingly a few days after the soil dries, as a guide; outdoors, rain alone is sometimes enough.
Light and placement for Welsh onion
A sunny, airy spot is about right; wet soil damages the roots, so use a free-draining mix, and for long white stems grow it in a deep container and hill up the soil a little at a time.
Overwintering Welsh onion
Overwintering guide: −10°C (14°F) or above
Very cold-hardy and generally left outdoors through winter; the leaf tips may wither, but the plant lives on and regrows in spring, and it can usually be harvested a little at a time all winter.
Fertilizing and repotting Welsh onion
Fertilizer
During growth, slow-release fertilizer about monthly or liquid feed about every two weeks is the usual guide; for long stems, hill up the soil with each feed but keep it below the point where the leaves fork.
When to repot
Spring–Summer (Mar–Sep), Autumn (Oct–Nov)
Common problems with Welsh onion
- Overwatering or poor drainage rots the roots and yellows the leaves.
- Rust spreads orange spots over the leaves in spring and autumn.
- Summer heat stalls growth and the stems stay thin.
Tips for growing Welsh onion
- Cut it 3 to 5 cm above the base and it regrows for repeated harvests.
- The rooted ends of store-bought scallions can be planted and will grow.
- A deep planter and gradual hilling give a long white stem.
These are AI-generated general guidelines. They vary with the variety, the placement and the pot size. For effects on pets or children, consult a veterinarian or a doctor.
Keep your plant log going
Greenery is a free app that keeps your plant care going, with watering reminders and photo records. Available on iOS and Android.
