Onion Growing Calendar: Sowing Through to Harvest

Autumn builds the foundation

Four fifths of the result is decided in autumn. Do not miss the sowing date, do not let the plants get fat, and finish planting while the roots can still move. Get those three right and even a hands-off winter and spring gives you a reasonable crop.

None of these can be recovered later. A week late sowing changes the size of the plants, and two weeks late planting means going into winter without roots. The flip side is that an autumn done carefully leaves very little to do until spring.

Sowing and planting both clash with other autumn jobs. Put those two dates in the diary first and arrange everything else around them.

Winter is about protecting

The tops barely move but the roots keep extending. There is little to do, so how often you look becomes what matters. After any hard freeze, check for plants that have been lifted.

What not to do in winter is clearer than what to do. Do not feed heavily, do not water, do not dig. Stick to pushing heaved plants back and weeding, and the crop comes away evenly in spring.

Midwinter is a month for doing nothing. The urge to intervene is strong, but adding neither feed nor water is the best management there is.

Spring switches to bulbing

As it warms the leaves extend quickly and the bulbs start to fill. The whole decision here is when to stop feeding. Make the feed at the start of spring your last, and after that stick to watering and watching for disease.

Bolted plants also become obvious now. A hard, round stem in the center means the bulb will not fill, so pull them as you see them and eat them as spring onions.

Early spring is the deadline for feeding. Even if the leaves look pale a month later, feeding then costs you the storage life of the whole crop.

Early summer is harvest and curing

The tops fall over in variety order through late spring and early summer. Once about eighty per cent are down, it is time to lift. From that point the whole game is drying, and the growing is essentially over.

The work after lifting falls in the same weeks. Two or three days drying in the open, then two to three weeks hanging somewhere airy. Skip that and bulbs that filled beautifully start to spoil before the summer is out.

Once a wet spell sets in you cannot cure the crop and storage life collapses. Some years it is right to lift on the forecast rather than wait for the last of the tops to fall.

What to record for next year

The weather changes every year, but your own records are what you actually decide from. Six things are enough: the sowing date, the planting date, the thickness of the plants, the feeding dates, the date eighty per cent of the tops went over, and how many bulbs rotted afterwards.

A year with a lot of bolting was a year you sowed too early or planted fat seedlings. Small bulbs mean close spacing or too little feed. Rot in store means late feeding or not enough curing. You only see the cause by putting it beside the record.