How Do I Know When My Sweetcorn Is Ready to Harvest?

Getting the harvest timing right is the single most important decision in growing sweetcorn. Pick too early and the kernels are watery and tasteless; pick too late and the sugars have converted to starch and the corn is tough and dull. There is a window of roughly three to five days for standard varieties, slightly longer for super-sweet types, when corn is at its best — and hitting that window is the whole game.

Check the silks first

The silks at the top of the cob are the first indicator. When they are fully brown and dry — completely dark and shrivelled from base to tip — the cob is at or near the harvest window. If any silks are still green or creamy-yellow, the cob is not yet ready. The silks brown as each one is fertilised; full browning means all potential kernels have been pollinated and the cob is at or approaching maturity. However, brownsilks alone are not sufficient — you need to do the kernel test too.

Feel the cob through the husk

Run your hand down the length of the cob through the husk. It should feel full and plump all the way to the tip. If the tip still feels thin and pointed, the kernels there have not filled yet and the cob needs more time. A cob that feels full and rounded at the tip with firm, packed kernels clearly visible through the husk is close to ready.

The milk test — the definitive check

Peel back a small section of the husk near the tip without removing it entirely, and pierce one kernel with a thumbnail or knife tip. At the ideal harvest stage, a milky white liquid will spurt out — this is the "milk stage." If the liquid runs clear and watery, the cob is still early; let it develop for two to four more days. If no liquid comes out, or the kernel is dry and doughy, you are past peak and the sugars have begun converting. Use the corn immediately even if slightly past peak — it will still be edible and far better than a supermarket cob.

Timing from pollination

As a rough guide, most sweetcorn varieties reach the milk stage around eighteen to twenty-two days after the silks first emerged (i.e., after pollination started). Keep a simple note of when silks appeared and begin checking from day fifteen. In hot weather this happens faster; in a cool summer it may take twenty-four days or more.

Harvest technique

To harvest, hold the stalk firmly with one hand, grip the cob with the other, and snap it downward sharply. It should come away cleanly. Cook immediately or refrigerate unhusked for no more than a few hours. For standard (su) varieties, cook within an hour of picking for peak sweetness. Super-sweet (sh2) varieties hold sweetness for several days in the fridge.