Sweetcorn is not the easiest crop to grow in the UK or Ireland. Or, more accurately, it is not easy to get a decent crop – the plants themselves grow perfectly well. It is a crop that needs warmth and sun. Many people make the mistake of either sowing too early or sowing in trays or strips. It always makes me wince when I see pots crammed with seedlings in spring – they will be so damaged by separating them that it would be better to walk past and buy seeds. Because, in most parts of the British Isles the plants cannot be planted out till late May, the time of the last frosts, you do not need to sow until mid- to late April – about six weeks before planting out.
I always sow in cell trays, the half tray size with twelve cells. Germination can be erratic or poor, though in theory it should be quick so sow two seeds per cell, keep at about 20c and pinch out the second seedling if two germinate.
With good growth, each plant should produce two cobs – you won’t get more, which is why I would not grow them in a poly tunnel even though they may crop earlier – they are too big to warrant the space they need.
It is recommended that the plants are grown in blocks and not rows – this is because the cobs are pollinated by wind – the pollen falling from the male flowers at the top of the plant onto the ‘silks’ below – the tassels of stigmas, each one connected to a single kernel on the cob. Even so, the cobs of plants around the edge of the block may not be pollinated thoroughly.
So, when do you pick them?
You need to pick them when they are at their peak, when sugar levels are highest. First, wait till the silks turn brown and wither.
Then pull back the sheaths until a kernel is exposed and press your nail into it. If the juice is watery, just pull back the sheaths and wait a little longer. If the juice is milky or yellow and opaque then the cobs are ready: pull the cob down and twist and it should come off with a satisfying snap.
I prepare the cobs by the plants: ripping off the sheath and snapping the cob off the small stem and snapping off the unfertilised top. This variety is Lark, an F1 hybrid and a tendersweet variety that has better germination than the supersweet varieties. It has an AGM and I defy you to taste sweeter sweetcorn, eaten raw, straight from the garden. It was years ago when an old gardener in Enfield suggested that sweetcorn could be eaten raw, straight from the plant and since then it is the way I prefer to enjoy it, something you can’t do with shop bought cobs since it loses crispness and sweetness as soon as it is picked.
Here is a cob from the edge of the block with poor fertilisation. Wet weather at flowering time cam cause this too.
By the way, sweetcorn always reminds me of the X-Files film when part of the plot was around bees pollinating sweetcorn — come on guys, I can believe aliens and mutants that can crawl through drains but bees pollinating sweet corn! The truth is out there – well here actually.