Onion ‘Senshyu Yellow’ (Autumn Planting)

Where to Plant

Plant Onion ‘Senshyu Yellow’ in an open, sunny position with fertile, moisture-retentive but well-drained soil. Before planting, remove weeds and improve the ground with well-rotted garden compost or other well-rotted organic matter if needed. Avoid fresh manure.

Good drainage is particularly important for autumn-planted onions, as sets can rot in heavy, waterlogged soil over winter. If your soil is very heavy and prone to winter waterlogging, a raised bed or large container may be a better option.

Onions prefer soil that isn't strongly acidic. If you know your soil is acidic, test its pH before adding garden lime and apply lime only if needed, ideally well ahead of planting.

Planting

Plant each set with the pointed end facing upwards, so the tip is just showing above the soil surface. Space ‘Senshyu Yellow’ sets around 10–15cm apart, with 30–45cm between rows, then gently firm the soil around them and water well.

When to Plant

Plant ‘Senshyu Yellow’ from around mid-September to mid-October. If autumn is particularly mild, plant towards the later end of this period to help reduce the risk of bolting. In colder conditions, plant earlier to give the sets time to establish before winter.

Growing in Containers

‘Senshyu Yellow’ can also be grown in a large container with good drainage. Fill with a good-quality peat-free compost, position in full sun and space the sets so the developing bulbs aren't crowded. Container-grown onions will need more regular watering than those growing in the ground.

Watering & Feeding

Onions have shallow roots, so don't let them become short of water while the bulbs are actively developing. Water during prolonged dry spells, giving the soil a thorough soak rather than frequent light watering.

Don't automatically stop watering as soon as the first tops begin to droop. If the bulbs are still actively swelling and the soil is dry, continuing to water for a little longer can help them fill out and produce plumper onions. Once the crop is reaching maturity and around half the tops have fallen naturally, stop watering so the bulbs can ripen and dry properly.

Well-prepared fertile soil should provide a good start. On poorer soils, autumn-planted onions can be given a suitable nitrogen-rich fertiliser in late winter. Avoid excessive nitrogen later in the season, which can encourage leafy growth at the expense of good bulb development.

Keep Them Weed Free

Onions don't compete well with weeds, so keep the ground around them clear throughout the growing season. Weed by hand close to the plants or hoe carefully between the rows to avoid damaging the shallow roots and developing bulbs.

Protecting Newly Planted Sets

Birds can sometimes pull newly planted sets from the soil before they've rooted properly. Check them regularly and gently push any disturbed sets back into place. Fleece or suitable netting can be used temporarily until the sets are securely rooted.

Watch for Bolting

Changes in temperature and other growing stresses can cause overwintering onions to bolt and produce a flower stem. Timing your planting carefully helps reduce the risk with ‘Senshyu Yellow’, particularly during a mild autumn. Remove any flower stems as soon as they appear and use these onions first after harvesting, as bulbs from plants that have bolted won't store as well.

Good Companions

Onions are easy to fit into a mixed vegetable plot thanks to their upright growth. Grow them alongside crops such as beetroot, lettuce and other leafy salads, making sure neighbouring plants don't shade or crowd the developing bulbs.

Making the Most of Your Bed

Quick-growing crops such as radishes and salad leaves can be grown nearby and harvested while your onions are still developing. Just make sure the onions continue to receive plenty of light and aren't crowded as the bulbs swell.

Crop Rotation

Avoid growing onions where onions, garlic, leeks, shallots or other alliums have recently been grown. These crops can be affected by some of the same soil-borne pests and diseases, so rotate them around the vegetable plot rather than repeatedly using the same ground.

Planning Ahead

An early harvest gives you another useful growing window. Once your ‘Senshyu Yellow’ onions have been lifted, use the cleared ground for later-sown salads, beetroot or other quick-growing vegetables for another harvest from the same bed.

When to Harvest

‘Senshyu Yellow’ can be ready to harvest from around June, with cropping continuing into July depending on your location, planting time and growing conditions. Yellowing and naturally toppling foliage is a sign that the crop is approaching maturity.

Don't Bend the Tops Over

There's no need to bend the foliage over by hand to encourage the bulbs to ripen. Let the leaves yellow and fall naturally, then harvest before the foliage has completely died back.

How to Harvest

Choose a dry day and carefully loosen the soil beneath each bulb with a garden fork. Lift the onions gently to avoid bruising or damaging them, as damaged bulbs are more likely to rot and should be used first.

Drying Your Onions

Spread freshly lifted onions out somewhere dry with plenty of air circulation, keeping the foliage attached while they cure. In suitable weather they can dry outdoors; if conditions are damp, move them into a greenhouse or well-ventilated shed. Wait until the necks and outer skins are thoroughly dry before preparing them for storage.

Storing Your Harvest

Store only sound, fully dried bulbs somewhere cool, dry and well ventilated, using net bags, slatted trays or a similar arrangement that allows air to circulate. Check them regularly and remove any that begin to soften, rot or sprout.

Top Tip

‘Senshyu Yellow’ earns its place in the vegetable plot for its valuable early harvest rather than exceptionally long storage. Use damaged bulbs and any onions that bolted first, then enjoy the rest of the crop while your later maincrop onions continue to develop.

Flavour

‘Senshyu Yellow’ has crisp white flesh with a mild, sweet flavour, making it a versatile onion for everything from fresh salads to everyday cooking.

Best Enjoyed

Slice fresh bulbs into salads and sandwiches, soften them into soups, sauces and curries or add them to casseroles and roasts. They're also delicious roasted, when their mild flavour becomes even sweeter.

Enjoy Them Young

You don't have to wait for every onion to reach full size. Harvest some young and use them much like spring onions in salads, leaving the rest of your crop to develop into mature bulbs for early summer.

From Plot to Kitchen

One of the real advantages of ‘Senshyu Yellow’ is its timing. Your crop can be ready before spring-planted maincrop onions, giving you fresh homegrown onions earlier in the season.

Top Tip

Try roasting smaller bulbs whole or halved rather than chopping them. Their mild flavour becomes beautifully sweet as they cook, making them ideal alongside roast vegetables or a Sunday roast.

What to Expect When They Arrive
Your onions are supplied as dormant sets in a netted bag, ready for planting. Sets are sold by weight, so the number of individual bulbs you receive may vary slightly from the approximate count shown on our website.

Ready to Plant
Your onion sets can be planted out as soon as they arrive. Each small bulb will establish roots and grow on to produce a mature onion ready for harvesting.

If You Can't Plant Straight Away
Remove the sets from their delivery packaging and keep them in their netted bag somewhere cool, dry and well ventilated until you're ready to plant. Check them occasionally and plant as soon as conditions allow.