How to Grow Giant Onions in the UK – Complete Exhibition Growing Guide

If you’ve ever wondered how to grow giant onions in the UK, the secret is to start with the right variety, sow early enough to develop strong plants, provide excellent light and maintain steady growth throughout the season. Giant exhibition onions require more attention than ordinary onion sets, but growing an enormous bulb can be one of the most satisfying challenges on an allotment.

There’s something fantastic about seeing a photograph of somebody holding an absolutely enormous onion.

You look at the bulb and wonder how on earth they’ve managed to grow something so big!

Well, the good news is that growing larger onions is something you can try on your own allotment.

You don’t need to be a professional exhibition grower to give it a go.

However, you’ll need to approach the crop a little differently from ordinary onions planted from sets during March or April.

Here at Gardening with Ben, I love the idea of experimenting with vegetables and discovering what’s possible with different varieties and growing methods.

And giant onions are a brilliant challenge because you can watch the plants develop throughout the year.

They begin as tiny seedlings.

Over time, they produce strong green leaves.

Then, as the growing season progresses, the bulbs begin swelling.

And if you’ve chosen a suitable variety and looked after it carefully, you may end up with an onion considerably larger than anything you’d normally find in the supermarket.

But there’s an important distinction between growing a large onion for cooking and producing an exhibition onion.

A large kitchen onion might be a fantastic achievement for a beginner.

A competitive show onion may require specialist seeds, supplementary lighting, additional spacing and months of careful attention.

In this complete guide, I’ll explain how to grow giant onions in the UK, from choosing the correct varieties to harvesting and weighing your finished bulbs.

We’ll cover The Kelsae, Ailsa Craig and other exhibition onions, along with sowing dates, germination, grow lights, potting on, soil preparation, spacing, feeding, watering and leaf support.

I’ll also discuss common problems such as bolting, small bulbs, weak seedlings and premature maturity.

So let’s see how big an onion we can grow!

What Is a Giant Onion?

A giant onion is a bulb onion selected and grown to achieve a larger-than-normal mature size.

Ordinary cooking onions are usually grown for practicality, flavour and storage.

Exhibition onions may be selected for size, shape and appearance.

Some gardening shows have specific classes for the heaviest onion.

Others have classes judged on the quality, uniformity and presentation of several onions.

The Royal Horticultural Society lists Ailsa Craig and The Kelsae as recommended varieties for onions over 250 g in traditional exhibition classes.

Its more recent vegetable exhibition guide also lists Kelsae and Showmaster.

Does Every Giant Onion Weigh Several Kilograms?

No.

That level of growth requires exceptional conditions, genetics and expertise.

Can Beginners Grow Large Onions?

Absolutely.

Even producing an onion noticeably larger than your ordinary cooking crop is a fantastic achievement.

Are Exhibition Onions Edible?

Yes, providing they’ve been grown using normal food-safe methods.

Do Giant Onions Taste Different?

Some large-bulb varieties are relatively mild, but flavour varies.

Are Giant Onions Good for Storage?

Some can be stored, but many exhibition types aren’t chosen primarily for keeping qualities.

Best Giant Onion Varieties to Grow in the UK

Choosing the right variety is the first major step.

You can’t assume that an ordinary bag of onion sets will produce enormous competition-sized bulbs.

Instead, choose seeds or plants specifically recommended for producing large onions.

The Kelsae

The Kelsae is one of Britain’s best-known giant onion varieties.

It’s associated with exhibition growing and can produce impressively large bulbs under suitable conditions.

Specialist growers often begin Kelsae seeds much earlier than ordinary kitchen onions.

For serious exhibition growing, supplementary lighting may be used during winter.

Ailsa Craig

Ailsa Craig is another famous onion variety.

It produces relatively mild, large bulbs and is recognised by the RHS for exhibition growing.

It’s a useful option if you want to try growing impressive onions without aiming for record-breaking weights.

Showmaster

Showmaster is included in the RHS exhibition guide as a variety suitable for show onions.

Look for suitable specialist seed and follow the breeder’s propagation instructions.

Other Exhibition Strains

Specialist growers offer carefully selected onion strains bred for large, well-shaped bulbs.

Some may be available from specialist UK seed suppliers rather than ordinary garden centres.

Which Would I Recommend for Beginners?

Start with Ailsa Craig or The Kelsae.

Grow several plants and compare the results.

Remember that the variety creates the potential for a large onion, but it doesn’t guarantee one.

When Should You Sow Giant Onion Seeds in the UK?

This is where exhibition growing starts to differ from ordinary onion growing.

For standard bulb onions, January and February are useful sowing months.

However, specialist exhibition growers sometimes begin during late November or December to create a longer growing season.

The aim is to establish strong plants with plenty of healthy leaves before bulb development becomes the main priority.

Can You Sow Giant Onions in November?

Yes, if you’re following specialist exhibition-growing instructions and have sufficient warmth and supplementary lighting.

Without suitable conditions, the seedlings may become weak.

Is December a Good Month?

For serious exhibition growing, it can be.

However, natural daylight is limited.

Can You Sow in January?

Absolutely.

January is a good compromise for gardeners who want large onions but aren’t aiming for competition records.

What About February?

Yes.

February is useful for producing large kitchen onions with less dependence on winter lighting.

Is March Too Late?

Not necessarily for growing onions, but late sowing reduces the time available to produce exceptionally large exhibition bulbs.

My Recommendation

If you’re trying giant onions for the first time, sow a few in January or February.

Only start during November or December if you’ve got the facilities to look after the seedlings properly.

Do Giant Onion Seedlings Need Grow Lights?

Supplementary lighting is one of the most important considerations for very early sowing.

During November, December and January, UK daylight hours are short.

Even a bright windowsill may not provide enough light for strong growth.

What Happens Without Enough Light?

Seedlings can become tall, thin and weak.

Can You Use an LED Grow Light?

Yes.

A suitable horticultural grow light can provide additional light during dark winter days.

How Long Should the Light Be On?

Follow the equipment manufacturer’s guidance and observe seedling growth.

Many growers provide a consistent extended daytime lighting period rather than leaving lights on continuously.

Do Onions Need Darkness?

Like most plants, they benefit from a regular day-and-night cycle.

Can You Grow Giant Onions Without Grow Lights?

Yes.

Starting in late winter when natural light improves is a practical alternative, although maximum exhibition potential may be reduced.

What Would I Choose?

For serious December sowing, I’d use suitable supplementary lighting.

For a straightforward allotment experiment, I’d start later rather than raise weak seedlings in poor light.

What Equipment Do You Need to Grow Giant Onions?

You don’t necessarily need lots of expensive equipment.

For a beginner, a few items will get you started.

You’ll need fresh giant onion seeds, clean propagation trays, suitable seed compost, labels and somewhere warm enough for germination.

A heated propagator can be useful.

You’ll also need larger pots for potting on, suitable potting compost, a bright growing area and a prepared outdoor bed.

Supplementary lighting is useful for very early sowing.

Do You Need a Heated Greenhouse?

Not necessarily.

You can germinate seeds indoors and move them to a cooler bright area once they’re growing, as conditions allow.

Do You Need Large Pots Immediately?

No.

Start with a suitable tray or module, then pot on progressively.

Do You Need Special Onion Fertiliser?

Not automatically.

Healthy soil and a balanced nutrient supply are more important than using lots of products.

Can You Reuse Pots?

Yes, provided they’re clean and suitable.

How to Sow Giant Onion Seeds – Step by Step

Let’s look at the sowing process.

Step 1: Choose Fresh Exhibition Seed

Use a suitable variety and check the packet’s sowing instructions.

Step 2: Prepare Your Seed Tray

Use clean modules or trays with drainage.

Step 3: Add Seed Compost

Fill with a suitable fine-textured peat-free compost.

Step 4: Moisten the Compost

Water lightly and allow excess moisture to drain.

Step 5: Sow the Seeds

Use the recommended depth on your chosen seed packet.

Different specialist growers recommend slightly different depths, often around 5–10 mm.

Step 6: Cover the Seeds

Apply a suitable fine layer of compost.

Step 7: Label the Variety

Record the sowing date.

Step 8: Provide Germination Warmth

Many specialist giant onion seed suppliers recommend approximately 18–21°C.

Step 9: Keep Compost Lightly Moist

Avoid waterlogging.

Step 10: Monitor Germination

Seedlings may begin appearing within approximately one to two weeks in suitable conditions.

Step 11: Provide Strong Light

As soon as the seedlings emerge, ensure they’re growing in bright conditions.

Step 12: Avoid Excessive Warmth After Germination

Once established, seedlings generally don’t need to remain in excessively warm conditions.

Step 13: Select Healthy Plants

Choose sturdy seedlings with good colour and growth.

Step 14: Prepare for Potting On

Move plants into suitable individual pots when necessary.

How to Pot On Giant Onion Seedlings

Giant onions need enough space for their roots to develop.

However, there’s no need to move tiny seedlings immediately into enormous pots.

Instead, pot them on progressively as their roots fill the existing compost.

When Should You Pot On?

When the roots are sufficiently developed and the plant needs more room.

What Compost Should You Use?

A suitable peat-free potting compost with appropriate nutrients.

Should You Handle the Seedling by Its Stem?

No.

Handle young plants carefully, supporting the root ball and avoiding damage to the growing point.

How Deep Should You Replant It?

Keep the plant at an appropriate level without deeply burying the base of the leaves.

Should You Water Afterwards?

Yes, enough to settle the compost.

Do You Need to Feed Immediately?

Not always.

Fresh potting compost may contain sufficient nutrients initially.

My Recommendation

Keep seedlings moving steadily into slightly larger containers when needed, but avoid unnecessary disturbance.

How to Grow Strong Giant Onion Plants Before Planting Outside

The aim during late winter and early spring is to produce strong, healthy plants.

You don’t want seedlings that are weak, pale or badly root-bound.

Provide Bright Light

This is especially important for winter-sown crops.

Maintain Sensible Temperatures

Avoid prolonged excessive heat.

Water Carefully

Check compost moisture regularly.

Allow Airflow

Good ventilation helps reduce overly humid conditions.

Check Root Development

Pot on when necessary.

Avoid Crowding

Give the foliage enough room.

Don’t Repeatedly Trim Healthy Leaves

The leaves are needed for growth.

Watch for Disease

Remove unhealthy plants and investigate any sudden collapse or decay.

When Should You Plant Giant Onions Outside?

Most giant onion plants are moved outdoors during spring after appropriate hardening off.

Specialist growers often plant during late April or May, depending on local conditions.

On a northern UK allotment, it’s especially important to consider frost, cold winds and soil moisture.

Can You Plant in March?

Some experienced growers use protected growing beds, but ordinary exposed outdoor planting may be risky for tender plants raised in warmth.

Is April Suitable?

Often, particularly later in the month when conditions improve.

What About May?

Yes.

Should You Harden Off?

Absolutely.

Gradually introduce plants to outdoor temperatures, sunlight and wind.

How Long Does Hardening Off Take?

Often around one to two weeks, adjusted for the conditions.

Can You Plant into Waterlogged Clay?

No.

Wait for workable ground or use a well-drained raised bed.

What Is the Best Soil for Giant Onions?

Giant onions need fertile soil that drains properly but also retains sufficient moisture.

Healthy soil structure is particularly important because the plants must grow strongly for several months.

Should You Add Garden Compost?

Yes, if needed.

Mature organic matter can improve soil structure and fertility.

Can You Use Well-Rotted Manure?

Yes, where appropriate and incorporated well before planting.

Should You Use Fresh Manure?

No.

Is Clay Soil Suitable?

It can be, provided drainage is adequate and the structure is well managed.

Should You Test the Soil?

A soil test can help identify nutrient and pH problems.

Do Giant Onions Need Full Sun?

Yes.

Choose a bright position sheltered from damaging wind.

Gardening with Ben Tip

Healthy soil with steady moisture is much more useful than trying to force growth with excessive amounts of fertiliser.

How Far Apart Should You Plant Giant Onions?

This is another important difference from ordinary kitchen onions.

Standard onion plants are often spaced around 10–15 cm apart.

That isn’t ideal if you’re trying to grow exceptionally large exhibition bulbs.

Some specialist exhibition growers recommend at least 30 cm between plants.

Elite growers may use substantially wider distances.

Is 30 cm Enough?

It’s a practical minimum starting point for some exhibition varieties.

Can You Use 45 cm?

Yes, when space allows.

What About 60 cm?

Some specialist methods use approximately 60 cm spacing for the largest exhibition bulbs.

Why So Much Space?

Large onions need adequate room for their foliage and developing bulbs.

Does Wider Spacing Guarantee Bigger Onions?

No.

What’s My Recommendation?

For a first giant onion experiment, start around 30–45 cm apart, checking your selected variety’s instructions.

If you’re aiming for competition-sized bulbs and have the space, consider a wider specialist layout.

How to Plant Giant Onions – Step by Step

Step 1: Prepare the Bed

Choose fertile, well-drained soil.

Step 2: Remove Weeds

Clear the area thoroughly.

Step 3: Improve Soil if Needed

Use mature compost or appropriate soil amendments.

Step 4: Mark the Spacing

Allow at least the cultivar’s recommended distance.

Step 5: Water the Seedlings

Moist root balls are easier to transplant.

Step 6: Lift Plants Carefully

Avoid unnecessary root damage.

Step 7: Make the Planting Hole

Allow enough space for the roots.

Step 8: Position the Seedling

Keep the growing point above the soil surface.

Step 9: Firm Gently

Ensure good root contact.

Step 10: Water In

Water appropriately.

Step 11: Label the Variety

Record the planting date.

Step 12: Protect Against Strong Winds

Temporary shelter may help young plants establish.

Step 13: Check the Plants

Monitor for stress during the following days.

How Often Should You Water Giant Onions?

Consistent watering is important if you want large bulbs.

Giant onions need steady growth rather than repeated cycles of drought and excessive watering.

Do They Need Water Every Day?

Not automatically.

What About Dry Spring Weather?

Water when the soil needs moisture.

Is Water Important During Bulb Development?

Yes.

Severe drought can restrict growth.

Can Too Much Water Cause Problems?

Absolutely.

Waterlogging can damage roots and encourage disease.

Should You Water the Leaves?

Where practical, apply water at soil level.

When Should You Reduce Watering?

As the crop approaches maturity.

My Recommendation

Check soil moisture beneath the surface and aim for even conditions throughout active growth.

What Is the Best Fertiliser for Giant Onions?

This is an area where gardeners sometimes make mistakes.

It’s tempting to believe that enormous onions need enormous amounts of fertiliser.

However, excessive feeding can create problems.

The specialist exhibition grower W. Robinson & Son advises that established fertile beds may not need additional feeding, and that overfeeding can produce thick-necked onions with poor storage qualities.

Is Nitrogen Important?

Yes, during early leaf growth.

Should You Apply Large Amounts?

No.

Can You Use General Fertiliser?

Yes, where a soil assessment indicates that additional nutrients are necessary.

What About Chicken Manure Pellets?

They can be used appropriately, but don’t apply excessive quantities.

Should You Feed Late in the Season?

Avoid unnecessary late nitrogen.

Can Too Much Fertiliser Make Bulbs Smaller?

Poorly balanced nutrition can interfere with normal growth and maturity.

My Recommendation

Prepare the bed properly and apply nutrients according to what the soil actually needs.

Why Leaf Growth Is So Important for Giant Onions

Healthy leaves are essential for developing large onion bulbs.

Before the bulb begins swelling strongly, the plant needs to establish sufficient foliage.

The leaves capture sunlight and produce energy through photosynthesis.

That energy supports bulb development.

Does More Healthy Leaf Growth Help?

Yes, within the variety’s natural growth pattern.

Should You Cut the Leaves?

Not routinely.

What if the Leaves Break?

Damaged leaves can reduce the plant’s productive area.

Do Exhibition Growers Support Leaves?

Some do.

How Can You Support Them?

Use suitable hoops or other gentle supports that prevent large leaves being damaged by wind.

Should You Tie Them Tightly?

No.

Avoid restricting growth or creating places where moisture remains trapped.

My Recommendation

Protect the foliage from avoidable damage, particularly on exposed allotments.

Growing Giant Onions in a Polytunnel

A polytunnel can provide useful protection for giant onion plants.

Specialist growers sometimes use protected structures to reduce wind and rain damage.

However, onion plants still need plenty of light and good ventilation.

Can You Grow Them Entirely Under Cover?

Yes.

Is an Unheated Polytunnel Suitable?

It may be, depending on the season and temperature.

Can the Tunnel Become Too Hot?

Absolutely.

Is Ventilation Important?

Very.

What About Humidity?

Excessively humid conditions can encourage disease.

Should You Grow Them in the Ground or Pots?

Both are possible, but soil beds may provide easier access to moisture and nutrients for extremely large plants.

My Recommendation

If you’ve got a polytunnel, consider trying a small number of giant onions under cover while growing others outside for comparison.

Growing Giant Onions in Raised Beds

Raised beds can be useful for giant onion growing, especially where the surrounding soil is heavy or difficult to manage.

However, giant onions require far more individual growing room than ordinary cooking onions.

Can You Grow Them at Standard Onion Spacing?

No, not if maximum size is the objective.

How Much Space Should You Allow?

Follow the specialist cultivar advice, often 30 cm or more between plants.

Do Raised Beds Need Good Soil?

Absolutely.

What About Drainage?

It’s essential.

Can Raised Beds Dry Out?

Yes.

My Recommendation

Dedicate a small section to a few well-spaced giant onions rather than crowding the entire bed with too many plants.

Why Are My Giant Onions Not Getting Bigger?

Sometimes a giant onion variety grows perfectly well but the bulbs don’t become particularly large.

There are several possible explanations.

Late Sowing

The plant may not have enough time to establish strong growth.

Insufficient Light

Weak seedlings may struggle later.

Root Restriction

Plants left too long in small pots can become stressed.

Poor Soil Fertility

Inadequate nutrients may affect growth.

Overfeeding

Excessive nutrients can also cause problems.

Dry Soil

Drought may restrict bulb development.

Waterlogging

Poor root health reduces growth.

Crowding

Insufficient space can limit bulb size.

Variety Limitations

Not every seedling will achieve the same mature size.

What Should You Do?

Review the full growing process, not just the fertiliser programme.

Why Are My Giant Onions Bolting?

Bolting occurs when the plant produces a flower stalk.

It’s usually undesirable when you’re aiming for a large, high-quality exhibition bulb.

Temperature conditions and plant development influence bolting.

Can Giant Onions Bolt?

Yes.

Is It More Common with Sets?

Sets generally carry a higher risk of bolting than seed-grown onions.

Can Very Early Sowing Create Problems?

It can if plants become excessively stressed by unsuitable conditions.

What Happens if a Flower Stalk Appears?

The bulb often becomes less suitable for exhibition or long-term storage.

Should You Remove the Stalk?

You can remove it and use the onion for cooking when appropriate.

Can You Prevent All Bolting?

No.

My Recommendation

Aim for steady, healthy growth and avoid unnecessary temperature and moisture stress.

Common Pests and Diseases of Giant Onions

Giant onions can suffer from the same problems as other bulb onions.

Onion White Rot

A serious soil-borne disease that damages roots and bulb bases.

Onion Fly

Larvae can damage bulbs and cause wilting.

Thrips

Small insects that feed on onion foliage.

Onion Downy Mildew

A disease that can cause significant leaf damage.

Neck Rot

Can affect harvested onions, especially during storage.

What Can You Do?

Start with healthy planting material, rotate crops where practical, maintain drainage and inspect plants regularly.

Why Is Leaf Health So Important?

Damaged foliage reduces the energy available for bulb development.

If you’re growing for exhibition, protecting healthy leaves is particularly important.

When Should You Harvest Giant Onions?

Giant onions generally mature during late summer, although the exact date depends on the variety, sowing time and growing conditions.

The leaves begin yellowing and naturally falling over as the plants reach maturity.

Should You Harvest as Soon as the Bulb Looks Big?

Not necessarily.

Allow the plant to finish developing appropriately.

What About Growing for a Show?

Check the exhibition schedule well in advance.

Some growers lift their onions approximately 10–14 days before a show to allow drying and presentation preparation.

Should You Force the Leaves Down?

Not as a routine growing technique.

Allow kitchen onions to mature naturally.

Can You Damage an Onion During Harvest?

Yes.

Bruising can affect storage quality and presentation.

How Should You Lift It?

Carefully loosen the ground and lift the bulb without pulling against the neck.

How to Prepare Giant Onions for an Exhibition

If you’re entering an allotment or horticultural show, read the competition rules before preparing the onions.

Not every show has the same classes.

Are All Shows Judged by Weight?

No.

Some are judged on size, shape, condition and uniformity.

Should You Clean the Onion?

Follow the show instructions and avoid damaging the skins.

Do You Need to Trim Roots?

Some exhibition rules require specific preparation.

Should You Remove Outer Skins?

Avoid unnecessary damage and check the judging requirements.

Can You Enter More Than One Onion?

That depends on the class.

Should You Weigh the Onion at Home?

Yes, if weight is relevant.

My Recommendation

Photograph the bulb, record its weight and keep notes about the growing method for next year’s attempt.

Can You Eat Giant Onions?

Absolutely.

Giant onions are edible and can be used in normal cooking.

Because they’re so large, one bulb may be enough for several meals!

Are They Good for Onion Soup?

Yes.

What About Onion Gravy?

They’re useful for producing a large batch.

Can You Roast Giant Onions?

Absolutely.

Can You Make Chutney?

Yes.

Should You Use Them All at Once?

Once cut, store the unused portion safely in the fridge and use it promptly.

Do They Store as Well as Ordinary Onions?

Not always.

Many giant exhibition varieties are best used sooner than specialist storage onions.

Giant Onion Growing Calendar for UK Gardeners

Month	Main job
November	Begin specialist early sowing only with suitable facilities
December	Sow exhibition seeds, provide warmth and supplementary light
January	Continue sowing, monitor seedlings and pot on
February	Maintain healthy leaf growth and increase pot sizes when needed
March	Prepare outdoor beds and begin careful acclimatisation
April	Harden off and plant outside when suitable
May	Complete transplanting, weed and monitor moisture
June	Maintain uninterrupted growth and protect foliage
July	Check bulb development and growing conditions
August	Begin harvesting mature large bulbs where appropriate
September	Harvest remaining onions and prepare show entries
October	Review results and plan the next season

Ten Common Giant Onion Growing Mistakes

1. Choosing an Ordinary Storage Onion

Use a variety with large-bulb potential.

2. Sowing Too Late for Exhibition Size

Give plants enough growing time.

3. Starting Early Without Sufficient Light

Weak seedlings are a poor foundation.

4. Leaving Seedlings Root-Bound

Pot on when necessary.

5. Planting Outside Without Hardening Off

Avoid sudden environmental stress.

6. Planting Too Closely

Giant bulbs need adequate space.

7. Allowing Soil to Dry Out Repeatedly

Maintain steady moisture during active growth.

8. Applying Excessive Fertiliser

More isn’t always better.

9. Damaging Healthy Leaves

Protect foliage from avoidable wind and handling damage.

10. Ignoring Exhibition Rules

Read the show schedule if you’re planning to compete.

Frequently Asked Questions About Growing Giant Onions

Can you grow giant onions in the UK?

Yes, many specialist varieties are suitable for UK gardens and allotments.

What is the best giant onion variety?

The Kelsae is well known for exhibition growing, while Ailsa Craig is another excellent large-bulb choice.

Is Showmaster an exhibition onion?

Yes, it’s listed in the RHS exhibition guidance.

When should you sow giant onion seeds?

Serious exhibition growers may sow from late November or December, while January and February are useful for ordinary large-bulb growing.

Can you sow giant onions in December?

Yes, with appropriate warmth and lighting.

Do giant onions need grow lights?

Supplementary lighting is particularly useful for very early sowing.

What temperature do giant onion seeds need?

Follow the packet instructions. Many specialist strains recommend approximately 18–21°C for germination.

How deep should giant onion seeds be sown?

Follow the packet instructions, which often recommend around 5–10 mm for specialist varieties.

Should you grow giant onions from sets?

Specialist exhibition onions are usually grown from seed or young plants.

When should giant onions be planted outside?

Often during late April or May, depending on local weather and how the plants have been raised.

How far apart should giant onions be planted?

Many exhibition growers allow at least 30 cm, with some specialist methods using considerably wider spacing.

Can you grow giant onions in raised beds?

Yes, provided there’s enough room and good soil.

Can you grow giant onions in a polytunnel?

Yes, with adequate ventilation and careful temperature management.

Do giant onions need lots of fertiliser?

They need adequate nutrients, but overfeeding can cause problems.

How often should giant onions be watered?

As needed to maintain steady moisture during active growth without waterlogging.

Why aren’t my giant onions getting bigger?

Late sowing, poor light, overcrowding, restricted roots or unsuitable moisture and fertility may be responsible.

Can giant onions bolt?

Yes.

Can you eat giant onions?

Absolutely.

Are giant onions suitable for storage?

Storage varies by variety, but many exhibition types aren’t the longest keepers.

When do giant onions harvest?

Generally during late summer, or according to the exhibition schedule.

Final Thoughts: Growing Your Biggest Onion Yet

For me, growing giant onions is one of those gardening challenges that makes an allotment even more exciting.

There’s something fantastic about starting with a tiny seed and seeing just how large the finished bulb can become.

You don’t have to be an experienced exhibition grower to give it a try.

And you certainly don’t need to aim for a world record on your first attempt.

Just growing an onion considerably bigger than your ordinary cooking onions is a brilliant achievement.

The most important thing is starting with a suitable variety.

The Kelsae and Ailsa Craig are excellent choices worth investigating.

Then think carefully about when to sow.

If you’re aiming for serious exhibition results, you may need to start during November or December.

But remember that very early seedlings require plenty of light.

For a simpler first attempt, January or February sowing can still produce impressive onions.

Once the seedlings are growing, give them suitable compost, enough root space and plenty of bright light.

Pot them on when necessary.

Then gradually harden them off before planting outside in suitable spring conditions.

When they’re in the ground, provide plenty of space.

Unlike normal onion sets, giant exhibition plants shouldn’t be crowded together.

Look after the soil, maintain steady watering and avoid unnecessary overfeeding.

And don’t forget about those lovely green leaves.

They’re essential for producing the energy that helps the bulb grow.

Then, as the summer progresses, keep checking how the onions are developing.

You might be surprised by how quickly the bulbs can swell under favourable conditions.

When harvest time arrives, carefully lift your biggest onion and see what you’ve managed to achieve.

You could even weigh it and record the result.

Then next year, see if you can beat your previous best!

That’s what I love about gardening.

There’s always something new to try, something to improve and another little challenge to enjoy.

And of course, once you’ve finished admiring your enormous onion, you can use it to make some fantastic meals.

Imagine how much homemade onion soup, onion gravy or chutney you could make with one giant bulb!

So why not give giant onions a go on your own allotment?

Start with a few seeds, look after them carefully and see what happens.

Keep smiling, keep shining, keep gardening with Ben!