maincrop(of fruit and vegetables) grown as the principal crop of a seasonThe Rhubarb and maincrop strawberries are grown together because they both need a permanent bed and the same amounts of manure. Thin the maincrop carrot seedlings to 20cm (8in) apart, early variety carrots to 13cm (5in) apart. Sow maincrop leeks, beetroot, winter cabbage, sprouting and perennial broccoli, autumn and winter cauliflowers, carrots, parsnips, kale and swedes outside. fruit or vegetables grown as the principal crop of a seasonI'm pretty pleased to say we still have a sack of last year's maincrop so we have achieved self-sufficiency in potatoes. Both second earlies and maincrop are available in supermarket stores and many farm shops throughout the year. It includes seed and early crop production as well as maincrop and all sizes down to 25 mm.