We planted 250 gm each of sets of Stuttgart Giant (Stuttgarter Reisen) on 26th November last year to overwinter, and Sturon on 14th March this year. I was still searching for the elusive Hercules, an absolute star two years ago - good tasting, big onions that did not produce a single flower, that stored, hanging in the cool, until we ran out the following March, and a Gardening Which recommended variety. In a fit of madness I bought 500gm of Centurion sets, GW Best Buy described as "mild" - as many sets again as we had already planted. They went in on 17th March.
This spring was warm and dry. Very dry. The onions sprouted, grew and stopped. Then the monsoon started, and the onions began to grow again, turning into lush plants. Quite a lot of the Stuttgart Giant bulbs split into two or more, like big shallots, as did several Sturon and Centurion.
|Split onion. The outer skin, instead of being dry and crisp, is soft and pappy|
The thick necks of the lush Centurion onions supported a good weight of leaves until the point where they began to fall over. To store onions properly, the necks need to be dry or you get black mould between the skins and the onion rots. The thicknecked onions can't dry out properly.
|Thick-necked Centurion onion with squishy decaaying leaves inside the neck|
The three conditions - thickneck, splitting and shank - are different sides of the same coin. An imbalance between nitrogen and potash in the soil is sometimes cited as the cause, but it really comes down to an irregular water supply putting the plant under stress. There's not a great deal you can do about it, except to water the onions when it's dry.The growth pattern of the onion layers is a giveaway: the outside layers filled out in spring, when it was dry, and these are so leathery as to be inedible. The inner layers date from the wet period, and are thick and juicy.
|Onion with Thickneck|
|Onion with a normal neck|
Potash helps the skin of the onion to ripen - to go a nice warm golden brown and dry out - so we treated the Centurion with a watering of dilute wood ash solution three weeks before we lifted them. Half a kilo of Centurion sets turned into 16 kilos of onions, according to our fishing scales. The really big ones are still drying out. The Sturon and Stuttgart are on strings, waiting to be hung in the Old Kitchen, which is cool and dry. We blogged about stringing onions here. The skinny shallots became Shallot Confiture.
|Shallot confiture, half way through (photographed using elderly Nokia mobile phone)|
We will have to monitor the condition of our stored onions very closely. That goes for the shallots and garlic too. And we'll look out for That Smell.