Asparagus from the UK is in season from late April / early May to around the end of June. In the USA the season starts earlier - around the end of February, but the peak months are April and May. You often see fresh green asparagus in supermarkets and outdoor markets during these periods. You can buy green asparagus in jars or cans; these are for sale all year round. Canned asparagus has far less flavour and is quite limp; it is always best to use fresh asparagus.