How to Grow White Onions in the UK – Complete Growing Guide

Learning how to grow white onions in the UK is a fantastic way to add something different to your vegetable garden or allotment. White onions produce attractive pale-skinned bulbs with crisp white flesh, and many varieties have a mild flavour that’s particularly useful for fresh cooking, salads, soups and roasting.

If you’ve been growing yellow and red onions for years, white onions are a lovely variety to add to your harvest.

They’re relatively straightforward to grow, provided you choose suitable planting material and give the plants the right conditions.

And there’s something especially satisfying about lifting those beautiful white bulbs from the soil after months of looking after them.

Here at Gardening with Ben, I love growing vegetables that we can use in different ways in the kitchen.

Yellow onions are brilliant for everyday cooking.

Red onions are fantastic for chutneys and roasting.

But white onions offer another option, particularly if you’re looking for a crisp texture and a comparatively delicate flavour.

One of the most familiar white bulb onion varieties available to UK gardeners is ‘Snowball’.

It produces attractive rounded bulbs with white skins and flesh and can be grown from suitable onion sets.

However, it’s important to understand that not every white onion is intended for the same growing season.

Some are sold for autumn planting, while others are available for spring.

White onions can also be grown from seed, and different varieties may have different storage characteristics.

In this complete growing guide, I’ll explain how to plant white onions, choose suitable varieties, prepare your soil and look after the plants through to harvesting.

We’ll also cover growing white onions in raised beds and containers, dealing with yellow leaves, avoiding bolting and making the most of your harvest.

So let’s get those white onions growing!

What Are White Onions?

White onions are varieties of the ordinary bulb onion, Allium cepa.

They produce bulbs with white or pale skins and white flesh.

They’re different from the more familiar golden-brown storage onions and purple-red onions, although their basic growing requirements are very similar.

Do White Onions Taste Different?

Many white onion varieties have a relatively mild, crisp flavour, making them useful for salads and fresh dishes.

However, flavour can vary between cultivars and growing conditions.

Are They Sweet Onions?

Some white onions are comparatively sweet, but skin colour doesn’t automatically determine sweetness.

Can You Cook With White Onions?

Absolutely.

They’re useful for soups, sauces, roasting, casseroles and many other dishes.

Are White Onions Difficult to Grow?

No.

If you’ve successfully grown ordinary onion sets, you’ll already understand most of the growing process.

Are White Onions the Same as Spring Onions?

No.

This guide is about growing full-sized bulb onions.

Salad onions, often called spring onions, are generally harvested young and have different growing and harvesting requirements.

Best White Onion Varieties to Grow in the UK

Choosing the right variety is important.

White bulb onions aren’t always stocked as widely as ordinary yellow sets, so you may need to look through specialist vegetable seed catalogues or garden suppliers.

Snowball White Onion

‘Snowball’ is one of the most recognisable white onion varieties available in Britain.

It produces rounded bulbs with bright white skins and crisp, mild-flavoured flesh.

It’s useful for eating fresh, roasting and general cooking.

Some UK suppliers offer ‘Snowball’ specifically for autumn planting.

Others also sell spring-planting sets.

Because supplier recommendations can differ, always check the planting instructions for the exact product you purchase.

Other White Onion Varieties

White onion varieties are also available from seed, including white globe and Spanish-style types.

When choosing seed, make sure the variety is suitable for UK day length and growing conditions.

Some onion varieties intended for warmer climates and shorter days may not perform as expected in northern England.

What About White Lisbon?

‘White Lisbon’ is a popular salad onion, not a standard full-sized storage onion.

It’s excellent if you want tender stems and small white bases for salads, but it’s not the same crop as ‘Snowball’ grown for mature bulbs.

My Recommendation

If you’re growing white bulb onions for the first time, start with a small quantity of ‘Snowball’ sets supplied with clear UK planting instructions.

When Should You Plant White Onion Sets in the UK?

The planting date depends on the variety and whether the sets are sold for autumn or spring planting.

Autumn Planting

Suitable overwintering white onion sets can be planted during September or October.

They establish roots before winter and begin growing more strongly as temperatures rise in spring.

Can You Plant Them in November?

Some supplier-approved overwintering sets can be planted later when the ground remains workable and well drained.

However, waterlogging and cold conditions increase the risk of poor establishment.

Spring Planting

White onion sets intended for spring are normally planted during March or April.

Wait until the ground is suitable rather than forcing bulbs into saturated soil.

Is February Too Early?

February may be suitable for starting spring sets in modules under cover.

Direct outdoor planting depends on soil and weather conditions.

Can You Plant White Onions in May?

May is getting late for ordinary maincrop onion sets.

Late planting can limit the amount of leaf growth produced before bulb development begins.

Gardening with Ben Tip

Never assume that a bag of white onion sets is suitable for autumn simply because another supplier sells the same named variety for overwintering. Read the packet and follow the advice for your actual sets.

Where Should You Grow White Onions?

White onions grow best in a sunny position with reasonably fertile, well-drained soil.

Good sunlight is particularly important because the green leaves produce the energy used for bulb development.

Do They Need Full Sun?

Ideally, yes.

Choose an area that receives plenty of daylight.

Can They Grow in Partial Shade?

They may grow, but bulb size can be reduced.

What Soil Is Best?

Fertile, workable soil that retains moisture without remaining waterlogged.

Can You Grow Them on a Northern Allotment?

Absolutely.

Choose varieties suitable for UK growing conditions and pay attention to the planting season.

What About Heavy Clay Soil?

Clay soil can support healthy onions, but drainage matters.

If the ground remains saturated for long periods, the bulbs and roots can become damaged.

Should You Rotate Crops?

Yes, where possible.

Avoid continually growing onions, garlic, leeks and shallots in the same ground.

How to Prepare the Soil for White Onions

Before planting, take time to prepare the bed properly.

Start by removing weeds and clearing away unwanted crop debris.

Onions have relatively limited root systems and don’t compete particularly well with weeds.

If the soil is compacted, improve it appropriately when conditions allow.

Mature garden compost or well-rotted organic matter can help maintain fertility and structure.

However, avoid using fresh manure directly around the onion sets.

Does the Soil Need to Be Fine?

A reasonably fine surface makes planting easier and helps the sets contact the soil properly.

Should You Add Fertiliser Before Planting?

Only when necessary for the existing soil.

A soil test can be useful if you consistently experience poor vegetable growth.

What if the Ground Is Waterlogged?

Wait for improved conditions or use a better-drained growing area.

Can You Use a No-Dig Method?

Yes.

Prepare a weed-free bed and plant through a suitable layer of mature compost.

What’s My Recommendation?

Healthy soil and good drainage are more important than applying large amounts of fertiliser.

How to Plant White Onion Sets – Step-by-Step

Planting white onion sets is much the same as planting yellow or red onion sets.

Step 1: Choose Healthy Bulbs

Select firm sets without obvious softness, mould or decay.

Step 2: Confirm the Planting Season

Check whether your sets are suitable for autumn or spring.

Step 3: Prepare the Bed

Remove weeds and ensure the ground is workable.

Step 4: Mark Your Rows

Leave approximately 20–30 cm between rows.

Step 5: Measure the Planting Distance

Allow around 10–15 cm between individual sets.

Step 6: Identify the Pointed End

This is where the leaves will emerge.

Step 7: Position the Root End Downwards

The flatter basal plate should contact the soil.

Step 8: Plant Shallowly

Position each set approximately 2 cm deep.

Step 9: Leave the Tip Visible

The pointed tip should just show above the soil.

Step 10: Firm Gently

Press the surrounding soil to keep the bulb secure.

Step 11: Water When Necessary

Water if the ground is dry, but avoid saturating it.

Step 12: Label the Crop

Write down the variety and planting date.

Step 13: Protect Against Birds

Use suitable temporary fleece or securely installed wildlife-safe netting if the sets are being disturbed.

Step 14: Keep the Bed Weed-Free

Remove weeds regularly throughout growth.

That’s the basic planting process.

How to Grow White Onions from Seed

Growing white onions from seed is another option, particularly if you want a cultivar that’s difficult to find as sets.

Seed growing is also useful if you want to produce a larger number of plants economically.

When Should You Sow?

For suitable maincrop varieties, start indoors during January, February or March.

Alternatively, sow outdoors during early to mid-spring when conditions are suitable.

How Deep Should Seeds Be Sown?

Approximately 1.3 cm, following RHS onion-growing guidance.

Can You Use Modules?

Yes.

Sow one seed per module for individual plants.

Can You Multi-Sow?

Yes.

Three or four onion seeds can be sown together if you want to grow groups of smaller bulbs.

Do Seeds Need Warmth?

Provide suitable conditions for germination according to the seed packet.

What Happens After Germination?

Move seedlings into bright conditions to encourage healthy, sturdy growth.

When Do You Plant Them Outdoors?

Usually in spring, after hardening off and when the soil becomes workable.

How Far Apart Should White Onions Be Planted?

The usual spacing for full-sized white onions is approximately 10–15 cm between plants, with 20–30 cm between rows.

However, it’s worth adjusting the spacing according to the size of bulb you’re hoping to harvest.

Want Larger White Onions?

Use the wider end of the spacing range.

Want Smaller Bulbs?

Closer spacing can be used where appropriate.

Do White Onions Need Different Spacing from Yellow Onions?

Not simply because of their colour.

Can You Plant in a Grid?

Yes, particularly in raised beds.

Should Seedlings Be Thinned?

Yes, if direct-sown too closely together.

What’s My Recommendation?

If you’ve got enough space, use approximately 15 cm between plants for a useful crop of mature cooking onions.

Growing White Onions in Raised Beds

Raised beds can provide excellent growing conditions for white onions.

They make it easier to organise planting and maintain a weed-free growing area.

They’re also useful when the natural soil is very heavy or difficult to manage.

Can You Plant Autumn White Onion Sets?

Yes, if the variety is suitable for overwintering.

Can You Plant Spring Sets?

Absolutely.

What Soil Should You Use?

Fertile topsoil improved with mature organic matter where needed.

Should You Use a Grid Layout?

You can.

Maintain suitable spacing between bulbs.

Do Raised Beds Need More Water?

Some raised beds dry out faster than ordinary ground.

Check moisture during dry weather.

My Recommendation

Raised beds are particularly useful if your outdoor allotment soil becomes excessively wet in autumn or early spring.

Growing White Onions in Pots and Containers

You can also grow white onions in sufficiently large patio pots.

The RHS recommends using a container at least 45 cm wide and deep for mature bulb onions.

Choose a suitable peat-free soil-based compost.

Make sure the pot has drainage holes and place it in a sunny position.

Can Snowball Onions Grow in Pots?

Yes.

UK suppliers sell ‘Snowball’ as suitable for container growing.

How Many Sets Should You Plant?

That depends on the usable container diameter and the spacing chosen.

Avoid overcrowding.

How Deep Should You Plant Them?

Approximately 2 cm, with the tips just visible.

Do Pots Need Extra Watering?

Often, especially during dry, windy weather.

Can You Overwater Container Onions?

Yes.

Standing water and permanently saturated compost can cause problems.

How Often Should You Water White Onions?

White onions need sufficient moisture during establishment and active growth.

However, they don’t generally need watering every day.

During ordinary wet British weather, outdoor crops may receive enough rainfall.

But during prolonged dry periods, additional watering can be helpful.

Should You Water Immediately After Planting?

Water if necessary to settle the soil around the roots.

What About During Bulb Formation?

Avoid prolonged drought while the plants are actively growing.

Does Winter Watering Matter?

Overwintering onions generally need little additional water in normal wet outdoor conditions.

Can You Water Too Much?

Absolutely.

Waterlogged ground can damage roots and encourage bulb rot.

When Should You Stop Watering?

Reduce watering as the bulbs approach maturity and the leaves begin naturally dying back.

Gardening with Ben Tip

Always check the soil before watering. The surface may appear dry while the ground underneath still contains plenty of moisture.

What Is the Best Fertiliser for White Onions?

White onions need nutrients for healthy foliage and bulb growth, but their feeding requirements aren’t fundamentally different from yellow or red onions.

Start with reasonably fertile soil.

Mature compost or well-rotted organic matter can be useful when preparing beds.

Can You Use Chicken Manure Pellets?

Yes, where appropriate, following the manufacturer’s instructions.

Do Onions Need Nitrogen?

Nitrogen supports healthy leaf development during early growth.

Can Too Much Nitrogen Cause Problems?

Yes.

Excessive late feeding can encourage leafy growth and may interfere with ripening and storage.

Should You Use Tomato Feed?

It isn’t essential.

Do Container Onions Need More Feeding?

They may, because nutrients in potting compost can become depleted.

My Recommendation

Focus on maintaining steady growth rather than trying to force large bulbs with repeated fertiliser applications.

Why Are My White Onions Small?

If your onions aren’t developing large bulbs, several growing conditions may be responsible.

Late Planting

Onions need enough time to establish strong leaves before bulb development.

Overcrowding

Plants growing too closely compete for resources.

Insufficient Sunlight

Poor light can limit photosynthesis.

Dry Soil

Prolonged drought can restrict growth.

Poor Soil Fertility

A lack of essential nutrients can affect leaf development.

Waterlogging

Roots may become damaged in saturated ground.

Variety Characteristics

Some cultivars naturally produce smaller onions than others.

What Should You Do?

Assess the planting date, spacing, soil conditions and plant health before applying more fertiliser.

Why Are My White Onion Leaves Turning Yellow?

Yellowing foliage can be normal when onions reach maturity.

However, it can also indicate stress or disease.

Normal Maturity

Leaves gradually yellow and fall over as the bulbs finish developing.

Waterlogging

Excessive moisture can damage the roots.

Drought

Dry conditions can cause leaf stress.

Nutrient Problems

Poor fertility may affect plant colour.

Onion White Rot

This serious soil-borne disease can cause yellowing, wilting and decay around the roots.

Onion Downy Mildew

Affected foliage may develop pale or yellow patches.

How Can You Tell the Difference?

Look at the whole plant, not just one leaf.

A large mature bulb with naturally collapsing foliage is very different from a young plant wilting in saturated soil.

Can White Onions Bolt?

Yes.

Bolting happens when an onion develops a flower stalk instead of concentrating on bulb formation.

Onion sets are generally more susceptible to bolting than seed-grown plants.

What Causes Bolting?

Temperature-related stress and the plant’s developmental stage are important factors.

Does the Planting Date Matter?

Yes.

Use the correct variety for the season.

Can Heat-Treated Sets Help?

Suitable heat-treated sets may reduce the risk of bolting.

What Happens if an Onion Flowers?

The bulb generally becomes less suitable for long-term storage.

Should You Remove the Flower Stem?

You can remove it and use the affected bulb promptly.

Can White Onions Be Grown from Seed to Reduce Bolting?

Yes.

Seed-grown onions often have a lower bolting risk, although it isn’t eliminated completely.

Common White Onion Pests and Diseases

White onions are vulnerable to many of the same problems as other bulb onions.

Onion White Rot

A serious soil-borne fungal disease that affects the roots and bulb base.

The disease can persist in contaminated soil for many years.

Avoid moving contaminated soil or growing alliums in known affected beds.

Onion Fly

Larvae may damage bulbs and cause plants to wilt.

Onion Downy Mildew

This disease can damage foliage, particularly during humid conditions.

Thrips

Small insects that may cause silvery or pale streaks on leaves.

Neck Rot

A storage disease that can cause bulbs to deteriorate after harvesting.

How Can You Reduce Problems?

Choose healthy planting material, maintain suitable drainage, rotate crops where practical and avoid storing damaged bulbs.

When Should You Harvest White Onions in the UK?

Harvesting depends on the variety and planting season.

Suitable autumn-planted white onions may be ready during June or July.

Spring-planted white onions usually mature from July into late summer or early autumn.

How Do You Know They’re Ready?

The leaves begin yellowing and naturally falling over.

The bulbs should have reached their mature size.

Can You Harvest White Onions Early?

Yes.

You can use younger bulbs fresh in cooking.

Should You Bend the Leaves Over?

No.

Allow the foliage to die back naturally.

How Do You Lift White Onions?

Carefully loosen the soil with a fork and lift the bulbs without bruising them.

What if the Weather Is Wet?

Harvest mature bulbs when appropriate and dry them in a sheltered, well-ventilated location.

How to Dry and Store White Onions

White onions can be cured in much the same way as yellow and red onions.

However, storage life varies substantially between cultivars.

Many white onions are particularly valued for fresh use, and some don’t keep as long as traditional yellow storage varieties.

After harvesting, place healthy bulbs somewhere sheltered with good airflow.

Avoid piling wet onions together.

Allow the skins and necks to become thoroughly dry.

How Long Does Curing Take?

Often around two weeks, although damp conditions may require longer.

Can You Cure Them in a Greenhouse?

Yes, if it’s well ventilated and doesn’t overheat excessively.

Can You Store Snowball Onions?

Yes, for a period, but suppliers differ in their storage descriptions and actual keeping quality depends on growing, curing and storage conditions.

What Is the Safest Storage Approach?

Use healthy, fully cured bulbs first, keep them cool and dry, and check them regularly.

Should You Store Damaged Onions?

No.

Use damaged or bruised bulbs promptly.

White Onions vs Yellow Onions – What’s the Difference?

Both are varieties of Allium cepa, but they differ in appearance and often flavour.

White onions have white skins and flesh.

Yellow onions usually have golden or brown outer skins.

Are White Onions Milder?

Many white onion varieties have a relatively mild flavour, but this isn’t a universal rule.

Are Yellow Onions Better for Storage?

Some traditional yellow storage varieties are excellent keepers.

White onion storage characteristics vary by cultivar.

Do They Need Different Soil?

No.

Both prefer sunny conditions and well-drained soil.

Can You Grow Them Together?

Absolutely.

Which Would I Recommend?

Grow yellow onions if you want a dependable everyday storage crop, then add some white onions for fresh cooking and variety.

Best Ways to Use Homegrown White Onions

One of the joys of growing white onions is deciding what to cook with them.

Fresh Salads

Finely sliced white onions can add texture and flavour.

Roasted White Onions

Smaller white bulbs can be roasted whole until tender.

Homemade Onion Soup

White onions can produce a different flavour from traditional yellow onions.

Cheese and Onion Pie

A lovely way to use your homegrown harvest.

Onion Gravy

White onions can be slowly cooked to develop sweetness and flavour.

Homemade Pickled Onions

Suitable smaller onions can be used in pickling recipes.

Caramelised Onions

Cook them slowly to develop deeper flavours.

One thing I love about allotment gardening is being able to plan meals around the vegetables you’ve harvested.

White Onion Growing Calendar

Month	Jobs
January	Choose varieties and begin suitable indoor seed sowing
February	Continue seed sowing and prepare spring beds
March	Plant suitable spring white onion sets
April	Finish spring planting and transplant established seedlings
May	Weed, check moisture and maintain healthy foliage
June	Begin harvesting suitable overwintering white onions
July	Harvest early mature crops and monitor spring onions
August	Harvest maincrop white onions and cure bulbs
September	Plant suitable autumn white onion sets
October	Complete normal autumn planting
November	Check drainage and overwintering crop health
December	Inspect stored onions and maintain winter beds

Ten White Onion Growing Mistakes to Avoid

1. Confusing White Bulb Onions with White Lisbon Salad Onions

They’re grown for different harvesting stages.

2. Planting the Wrong Sets in Autumn

Follow the exact supplier’s planting advice.

3. Planting into Waterlogged Soil

Poor drainage can damage the bulbs.

4. Planting Sets Too Deeply

Keep the pointed tips just visible.

5. Overcrowding

Allow sufficient space for bulb development.

6. Growing in Too Much Shade

Choose a sunny location.

7. Allowing Weeds to Establish

Onions compete poorly with weeds.

8. Overwatering

Excess moisture can encourage root problems.

9. Applying Excessive Late Nitrogen

This may delay maturity and reduce storage quality.

10. Assuming Every White Onion Stores for Months

Storage depends on the variety and curing conditions.

Frequently Asked Questions About Growing White Onions

Can you grow white onions in the UK?

Yes, white bulb onions can grow successfully in suitable UK gardens and allotments.

What is the best white onion variety for the UK?

‘Snowball’ is a popular and widely available white bulb onion worth considering.

Are white onions easy to grow?

Yes. Their basic requirements are similar to yellow and red bulb onions.

Can you plant white onions in autumn?

Yes, if you’ve bought suitable overwintering sets.

Can you plant white onions in spring?

Yes, with suitable spring-planting varieties or sets.

When should you plant Snowball onion sets?

Follow the supplier’s directions. Both autumn and spring planting products are sold under the name ‘Snowball’.

How deep do you plant white onion sets?

Approximately 2 cm, with the pointed tips just visible.

How far apart should white onions be planted?

Usually 10–15 cm.

Can you grow white onions from seed?

Yes.

Can you grow white onions in raised beds?

Absolutely.

Can you grow white onions in pots?

Yes, in sufficiently large containers.

Are white onions the same as spring onions?

No. White bulb onions are grown for mature bulbs; salad onions are generally harvested young.

Is White Lisbon a bulb onion?

It’s normally grown as a salad onion.

Can white onions grow in clay soil?

Yes, provided drainage is suitable.

Do white onions need fertiliser?

They need adequate nutrients, but extra fertiliser should depend on soil fertility.

Why are my white onions small?

Late planting, overcrowding, poor light, drought or nutrient problems may be responsible.

Why are the leaves turning yellow?

It may be normal maturity or a sign of water stress, nutrient problems or disease.

Can white onions bolt?

Yes.

When do you harvest white onions?

Usually summer to early autumn, depending on variety and planting date.

Can you store white onions?

Yes, but storage life varies considerably between varieties.

Are white onions good for cooking?

Absolutely. They’re useful in salads, roasting, soups, sauces and many other dishes.

Final Thoughts: Are White Onions Worth Growing?

For me, white onions are a fantastic vegetable to add to your allotment growing plan.

If you’ve always grown traditional yellow onions, why not try something different next season?

White onions look beautiful when harvested, and their crisp, pale flesh makes them a lovely ingredient for fresh cooking.

One variety I’d particularly recommend looking at is ‘Snowball’.

It’s a well-known white bulb onion that produces attractive rounded bulbs and is available from UK suppliers.

Just remember to check whether the sets you’ve purchased are intended for autumn or spring planting.

Choose a sunny position, prepare the soil properly and make sure the ground drains adequately.

Plant your onion sets at the correct depth, keeping the pointed tips just visible.

Allow around 10–15 cm between bulbs and keep the growing area weed-free.

During spring and early summer, check moisture levels and water when necessary.

And if your soil is particularly heavy or wet, consider using raised beds or starting the plants in modules.

Once the leaves begin yellowing and falling naturally, you’ll know the bulbs are approaching maturity.

Lift them carefully and decide how you’d like to use your harvest.

If you’ve grown a variety that’s particularly good for fresh eating, there’s no need to keep every bulb in storage for months.

Enjoy them while they’re fresh!

You could roast smaller white onions whole, slice them into salads or turn them into a delicious homemade onion soup.

And of course, why not grow some alongside your yellow and red onions?

It’s a fantastic way to compare different varieties and discover which ones perform best in your garden.

Keep smiling, keep shining, keep gardening with Ben!