Senshyu Yellow Onions

How to Grow Senshyu Yellow Onions: An Easy Guide to Overwintering Onion Sets

Growing onions doesn't have to start in spring. In fact, autumn is a brilliant time to get some onions into the garden.

This year, I'm planting Senshyu Yellow onion sets in the Organic Yarden, so I thought I'd take you along for the journey from planting these tiny little sets in autumn to hopefully harvesting a lovely crop of golden-brown onions next summer.

If you're new to growing vegetables, overwintering onions are a great place to start. They don't need a huge amount of space, they're relatively straightforward to grow and, once planted, they spend the winter quietly getting themselves established while we gardeners can get on with everything else.

And let's be honest, anything that does some of the work while we're drinking tea is a winner in my book!

How to Plant Senshyu Yellow Onion Sets

Planting onion sets is wonderfully simple.

Step 1: Prepare your soil

Make sure the soil is loose, weed-free and drains well.

Level the surface and firm it lightly.

Step 2: Plant the sets

Take an onion set and look for the pointed end.

That's the top.

Place the set into the soil with the pointed end facing upwards.

The tip should remain just above the soil surface, rather than burying the entire set.

Seeds Ireland recommends planting them around 2–3 cm deep.

Step 3: Give them space

Plant the sets approximately:

10–12 cm apart

with around:

25–30 cm between rows.

If you're aiming for larger bulbs, you can give them a little more space.

Step 4: Water them in

Give the newly planted sets a good watering to settle the soil around them.

After that, don't keep the soil permanently wet.

 Remember: moist is good; soggy is not.

Do You Need to Protect Onion Sets From Birds?

Possibly.

This is one of those slightly annoying gardening surprises.

Birds can sometimes pull newly planted onion sets out of the soil, particularly when the ground is freshly disturbed.

If birds are causing problems in your garden, you can temporarily cover the planting area with suitable garden mesh or fleece while the sets get established.

You don't necessarily need to protect every planting, but it's worth keeping an eye on them during those first few weeks.

Caring for Senshyu Yellow Onions Through Winter

Once your onions are planted, there isn't an enormous amount to do.

And that is one of the lovely things about overwintering onions.

They'll settle in and continue developing their roots while temperatures are cooler.

Keep the area weed-free

Onions don't like competing with weeds.

Their foliage isn't particularly good at shading out surrounding plants, so weeds can easily compete with them for water and nutrients.

Regular gentle hand-weeding is usually all that's required.

Be careful around the bulbs and don't disturb their roots unnecessarily.

Keep an eye on moisture

Autumn and winter in Ireland can provide plenty of rain, so you may not need to water at all.

If your garden is experiencing a particularly dry period, check the soil and water when necessary.

What about frost?

Senshyu Yellow is an overwintering variety and is described as hardy.

In most situations, autumn-planted sets don't need special winter protection.

The bigger concern in a wet Irish winter is often poor drainage rather than frost.

Looking After Senshyu Yellow Onions in Spring

This is when things start getting exciting. As temperatures rise and daylight increases, your onions will begin putting on more growth.

Keep the planting area weed-free and monitor moisture levels. Spring is also when the onions will need a steady supply of water if the weather is dry. The aim is to keep the soil evenly moist without creating waterlogged conditions.

Seeds Ireland recommends a light nitrogen feed in early spring if needed, but feeding should stop once the bulbs begin swelling.

For an organic garden, I'd always start with healthy soil and mature compost rather than automatically reaching for fertiliser.

Can You Grow Senshyu Yellow Onions in Containers?

Absolutely.

This is particularly useful if you have a small garden, balcony, courtyard or, like me, a garden made up of lots of containers.

The important thing is to choose a container with:

• Good drainage holes

• Enough depth for the roots

• Quality growing medium

• Enough surface area to give the onions room to develop

Don't squash dozens of onion sets into a tiny container simply because you can.

Give them room.

A little breathing space can make a big difference to the size and health of your crop.

And don't forget to place your container somewhere sunny.

Do Onions Need Feeding?

They need nutrients to grow, but more isn't necessarily better.

If your soil is healthy and contains plenty of organic matter, you may not need to do much.

If the plants need a little extra help in spring, a suitable organic fertiliser can be used according to its instructions.

Avoid continually feeding onions with high-nitrogen fertiliser.

We want the plant to develop healthy bulbs, not produce enormous amounts of leafy growth at the expense of the bulb.

Common Problems When Growing Onions

Like everything in the vegetable garden, onions aren't completely trouble-free.

Bolting

Sometimes onions produce a flower stalk rather than putting all their energy into the bulb.

Cold weather can contribute to bolting.

If you notice a flower stalk developing, remove it promptly. Those onions are best used sooner rather than later because they generally won't store as well.

Onion pests:

 Onions can be affected by pests such as onion fly and thrips.Good garden hygiene, crop rotation and physical protection such as fine mesh can help reduce problems.

Onion diseases

Good crop rotation is important.

Avoid growing onions, garlic and leeks in the same area year after year. A rotation of several years is helpful where space allows.

Good drainage and avoiding moving contaminated soil around the garden are also important.

When Are Senshyu Yellow Onions Ready to Harvest?

Eventually, all that waiting pays off.

Your onions are approaching harvest when:

• The leaves begin turning yellow

• The foliage starts to fall over

• The neck of the onion begins to soften

• The outer skin becomes dry and papery

The exact timing will depend on the season and growing conditions.

June to July is the general harvest period for autumn-planted Senshyu Yellow sets.

Try to choose a dry spell for harvesting if possible.

Gently loosen the soil around the bulb with a garden fork and lift the onion carefully.

Don't pull aggressively on the leaves or bruise the bulbs.

How to Cure Your Onions

If you want your onions to store well, curing is an important step.

After harvesting, allow the onions to dry somewhere warm, dry and well ventilated.

Lay them out in a single layer, making sure air can circulate around them.

I recommends allowing around 10–21 days for curing, depending on conditions. The onions are ready when the necks are dry and the skins have become properly papery.

Don't wash your onions before storing them.

Instead, gently brush away loose soil once they're completely dry.

How to Store Senshyu Yellow Onions

Once properly cured, store your onions somewhere:

• Cool

• Dry

• Dark

• Well ventilated

Avoid storing them in sealed plastic bags.

Mesh bags, crates or traditional onion braids allow air to circulate.

Check your onions regularly and remove any that become soft, damaged or start to rot.

Use damaged or thick-necked onions first because they won't generally store as well.

My Senshyu Yellow Onions in the Organic Yarden

This year I'm growing Senshyu Yellow onion sets here in the Organic Yarden, and I'll be documenting how they perform throughout the growing season.

I'll be watching for:

Autumn:
Planting and establishment

Winter:
How they cope with the colder weather

Spring:
New growth and bulb development

Early summer:
Bulb swelling and signs of maturity

Summer:
Harvesting, curing and storing. 

That's one of my favourite things about growing vegetables. You don't just plant something and suddenly have a harvest.

You get to watch the whole story unfold. And sometimes there are surprises along the way. That's gardening!

Senshyu Yellow Onion Growing Calendar for Ireland

Time of year                                                                                                      What to do

September                                                                                       Start planting autumn onion sets

October                                                                                            Continue planting if conditions are suitable

November                                                                                        Final opportunity for planting

Winter                                                                                              Check drainage and keep weeds under control

March - April                                                                                    Watch for new spring growth

April–May                                                                                        Weed, water during dry spells and feed if needed

June                                                                                                Watch for bulbs maturing

June–July                                                                                        Harvest when tops yellow and fall over

After harvest                                                                                    Cure thoroughly

After curing                                                                                      Store somewhere cool, dry and well ventilated

My Top Tips for Growing Senshyu Yellow Onions

1. Don't plant into waterlogged soil.
Good drainage is one of the most important things you can provide.

2. Don't bury the sets too deeply.
Plant them with the pointed tip facing upwards and just showing above the soil.

3. Keep weeds under control.
Onions don't enjoy competing for nutrients and water.

4. Don't overwater.
Especially during a wet Irish winter.

5. Give them sunshine.
A sunny position will help them grow well.

6. Be patient.
You planted them in autumn. You're going to have to wait until summer for the full reward!

7. Cure them properly.
Good curing is essential if you want your onions to store well.

8. Grow organically wherever you can.
Healthy soil, compost, crop rotation and encouraging biodiversity all help create a healthier garden.

Final Thoughts

There's something rather satisfying about planting a tiny onion set in autumn and knowing that, several months from now, it could become a beautiful homegrown onion for the kitchen.

That's one of the joys of growing your own food. You don't need acres of land. You don't need a perfect garden. And you certainly don't need to know everything before you start.

You just need a little space, some patience and the willingness to give things a go.

So I'm planting my Senshyu Yellow onions here in the Organic Yarden, and now...

we wait.

I'll be back with updates as they grow. Because that's gardening one tiny onion at a time.

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