How to Plant and Grow Spring Onions Successfully: A Complete UK Guide

Introduction

Spring onions—also known as scallions or salad onions—are a quick, easy, and versatile crop that can be grown in gardens, allotments, containers, and even window boxes. With their mild onion flavour, crisp stems, and fast-growing nature, spring onions are a favourite among beginner and experienced gardeners alike.

Whether you want to add a crunchy kick to your salads or garnish dishes with fresh, homegrown green onions, this guide will show you exactly how to plant and grow spring onions successfully from seed to harvest.

Why Grow Spring Onions?

⏱️ Quick to mature – Ready to harvest in 8–10 weeks
🌿 Low maintenance – Minimal space and care required
🪴 Perfect for containers – Ideal for patios, balconies, and small gardens
🥗 Versatile – Use raw or cooked in a wide range of dishes
🌱 Successive sowing – Allows for continual harvests through spring, summer, and autumn

Best Spring Onion Varieties for UK Gardens

Variety	Description	Notes
White Lisbon	Fast-growing, mild flavour	Traditional UK favourite, suitable for spring and summer
Ishikura	Long, straight stems, no bulb	Excellent for Japanese dishes and bunching
Performer	Deep green leaves, upright habit	Great disease resistance and uniform growth
North Holland Blood Red	Mild flavour, red skins	Colourful addition to salads and dishes
Apache	Compact, red-skinned variety	Ideal for containers or raised beds

Tip: Choose a mix of white and red varieties for attractive harvests and extended cropping seasons.

When to Plant Spring Onions in the UK

Sowing Time	Harvest Time
Indoors/under cover: Feb–Mar	April–May
Outdoors: March–July	May–September
Autumn sowing (hardy varieties)	Aug–Oct (under cloches)

For a continuous harvest, sow every 2–3 weeks during the main season.

Where to Grow Spring Onions

Spring onions thrive in:

Raised beds or vegetable patches
Containers, window boxes, or grow bags
Greenhouses or cold frames for early/late crops

Ideal Growing Conditions:

Full sun to light shade
Moist but well-drained soil
Neutral to slightly alkaline pH (6.5–7.5)
Light, fertile soil enriched with compost or organic matter

How to Plant and Grow Spring Onions: Step-by-Step

Step 1: Prepare the Soil or Containers

Spring onions prefer light, fine-textured soil.

Garden Beds or Raised Beds:

Rake soil to a fine tilth
Remove stones and clumps
Add compost or general-purpose fertiliser before sowing
Avoid fresh manure—it can lead to fungal issues

Containers:

Use a shallow, wide container at least 15–20cm deep
Fill with a light compost mixed with sand or vermiculite for drainage
Ensure proper drainage holes to prevent soggy roots

Step 2: Sow the Seeds

Direct Sowing Outdoors:

Create shallow drills 1–1.5cm deep
Space rows 15–20cm apart
Sow seeds thinly – about 1–2cm apart
Cover lightly with soil and water gently

Sowing in Containers:

Broadcast seeds evenly across the surface
Cover with a thin layer of compost or vermiculite
Water gently using a rose-headed watering can

Step 3: Care and Maintenance

Watering:

Keep soil consistently moist, especially in dry periods
Avoid overwatering or letting soil dry out completely
Water early in the day to prevent disease

Feeding:

Spring onions are light feeders
Apply a liquid seaweed feed or general-purpose fertiliser every 2–3 weeks if needed

Thinning:

If sown thickly, thin seedlings to 1–2cm apart once they’re 5–7cm tall
Use the thinnings as microgreens or in salads

Weeding:

Weed regularly to avoid competition
Be gentle—spring onion roots are shallow

Growing Spring Onions in Containers

Perfect for beginners and small spaces.

Top Container Growing Tips:

Choose a wide pot with at least 15cm depth
Sow thinly and water frequently
Harvest earlier for tender baby onions
Great for balconies, patios, or even kitchen windowsills

Companion Planting with Spring Onions

Good Companions:

Carrots – spring onions deter carrot fly
Beets – grow at different depths, no competition
Lettuce – matures quickly and shades soil
Strawberries – onions deter pests without affecting fruit

Avoid Planting Near:

Beans and peas – onions may inhibit legume root growth

Common Problems and How to Avoid Them

Problem	Symptoms	Solution
Bolting (early flowering)	Flower stalks appear	Sow at correct times, avoid drought, use bolt-resistant varieties
White rot	Yellowing, collapsing plants	Practice crop rotation, avoid planting onions in same spot each year
Onion fly	Maggots in base of stem, wilting plants	Use insect mesh, rotate crops, sow early
Slugs and snails	Damaged young seedlings	Use organic pellets or barriers, water in the morning

Harvesting Spring Onions

When to Harvest:

8–10 weeks after sowing
Harvest when stems are pencil-thick (1cm diameter)
For baby spring onions, harvest even earlier at 4–6 weeks

How to Harvest:

Use a hand fork to loosen soil if needed
Gently pull the plant from the base
Trim roots and remove outer leaves if dirty
Wash and use fresh, or store in the fridge

Pro Tip: Harvest regularly to encourage new sowings and keep the bed productive.

Storing and Using Spring Onions

Storage Tips:

Store unwashed in the fridge in a plastic bag for up to 1 week
Alternatively, stand in a glass of water to keep fresh for a few days
Freeze chopped spring onions for cooked dishes only

How to Use:

Raw in salads, wraps, or salsas
Stir-fried with noodles or rice
Grilled whole as a BBQ side
Added to omelettes, soups, or marinades

Succession Sowing for Continuous Harvests

To enjoy spring onions over a long period:

Sow every 2–3 weeks from March to July
Choose a mix of early and late varieties
Protect later sowings with cloches or fleece in autumn
Grow under cover or in a greenhouse during winter for a supply of baby onions

Spring Onion Crop Rotation and Soil Health

Spring onions are part of the allium family (along with garlic, leeks, and onions)
Rotate with legumes, brassicas, or root vegetables to prevent disease build-up
Avoid planting in the same bed more than once every 3–4 years

Growing Spring Onions Indoors

Indoor Tips:

Use a shallow tray or pot with drainage
Sow thinly and harvest as baby greens
Place on a sunny windowsill
Great for winter growing and snipping fresh into salads or soups

Conclusion

Growing spring onions is one of the easiest and most rewarding gardening tasks you can take on. Whether you’re sowing directly in your veg patch, using window boxes, or filling a few pots on your patio, these speedy, low-maintenance crops deliver crunchy, flavour-packed harvests with minimal fuss.

By following this guide, sowing successively, and harvesting at the right time, you’ll enjoy a constant supply of spring onions from early spring into autumn—and even year-round if grown under cover.