Onion - Japanese


Common Name: Autumn sown onions

Autumn sown onions make a useful catch crop to give a crop of onions a couple of months earlier than the normal spring sown varieties.

Apart from the timing they are grown in a similar manner to maincrop onions!

Autumn varieties do not keep in storage as long as maincrop spring varieties.


Week 25:

Sow early maturing Japanese onion seed thinly in drills spaced 300mm (12”) apart.

Apply general fertiliser before sowing.

If conditions are dry, trickle water along the length of the drill prior to sowing.

Alternatively, sow in trays / cells or punnets and germinate in a coldframe.

Subject to ambient temperatures seeds should take seven to ten days to germinate.

Sowing one or two seeds per cell

Week 30:

As soon as they reach the crook stage, and the second leaf appears, prick out seedlings into 70mm (3”) pots of any proprietary soil-less potting compost.

Grow on, giving them plenty of light, but being careful not to force them with too much heat, and too much water, 8°-10°C (45°-50°F) will do.

Ready for Pricking out
Crook stage
Seedlings pricked out
Growing on

Watering depends so much upon the weather, so always allow them to dry out between each watering.

It is advisable to spray seedlings, from the second leaf stage with a fungicide at regular intervals to deter damping off.

Week 38 - 40:

Prepare beds, best results are achieved if the seedlings / setts are planted in soil that has been deeply dug and dressed with a general fertiliser at a rate of about 100gms (3oz) per sq metre.

Dig in organic matter
Add General Fertiliser (optional)
Rake in Fertiliser
Bed ready for Planting out

Week 38-40:

Plant out seedlings / setts any time from now until the middle of November.

Ideally, plant setts as soon as they delivered / purchased, having said that: they can be planted as late as November.

Plant the seedlings / setts out 150mm (6") apart, in rows 300mm (12") apart.

Planted Out
Various Stages of Growth

Week 43:

Check rows of seed that were sown insitu and thin the seedlings to about 25mm (1”) spacing.

Ideally they should reach up to about 150mm (6”) tall this month, but if growth has been slow due to heavy rain leaching out nutrients on poor soils, apply Nitro-chalk along the rows at a rate of 80gms (3oz) per sq metre.

There is still time to plant setts if you are having problems with your seed sown onions.

Week 10 - 12: (the following year)

Boost growth by hoeing in nitro-chalk or sulphate of ammonia at a rate of 1oz (30g) per sq m to, or alternatively, 3oz (90g) per sq m of growmore.

Circa Week 25 - 32:

If ready pick onions planted out the previous autumn.

Harvested Onions
Laid out to Dry
Ready for Storage
In Storage

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