1. Sweet corn is adjusted to the conditions of North America. British climatic conditions differ from American in the longer summer day-length and in lower spring soil temperature. Cold hardiness, i.e. the ability of the seed to germinate after lying in cold, wet soil, is therefore an important factor when introducing sweet corn into Britain.

2. Varieties germinate differently according to when they are sown. Furthermore some varieties germinate better than others in March and even April, thus demonstrating the genetic nature of cold hardiness.

3. Selections were first made from plants surviving March sowings and in later years, as hardiness increased, from those surviving February sowings.

4. Selections for hardiness were made in (i) Canada Gold, (ii) Early Golden Market sweet corn, (iii) Golden Standard Maize dent corn and (iv) derivatives of Peruvian crossed sweet corn.

5. All responded rapidly in their increased ability to germinate from February sowings except the Peruvian sweet derivatives which failed to show much improvement.

6. Future breeding work in Britain depends on establishing from our selections cold hardy inbreds able to combine well in giving good F1's for commercial use.