Protective coverings such as hotcaps and rowcover systems also help these crops cope with the cold weather. For years, transparent hotcaps have been used to speed the growth of vegetables during the cool days of spring. These small covers produce a warm, sheltered, humid environment ideal for plant growth. Each plant grows in its own hotcap until warm weather arrives or the plant outgrows its protective cover. The hotcaps protect against light spring frosts, allowing early planting.
Insects also find it difficult to locate the plants under the protective caps.
Rowcovers Recently, innovative growers have begun covering one or more rows of vegetables with a single sheet of transparent material. This rowcover system provides all of the growth promoting advantages of hotcaps but is easier to install, covers a larger area at a lower price and may be used to protect both direct seeded as well as transplanted crops. In tests conducted by the Horticulture Department at the University of Saskatchewan rowcovers have benefitted many vegetable crops under local growing conditions. Sweet corn planted under rowcovers emerged 3 days earlier and matured 10 days earlier than unprotected plants. Protected muskmelons yielded four times as many mature fruit by the first fall frost as plants grown without the covers.