354 
VEGETABLE GARDENING 
Eclipse or Express, Dwarf White Heart and Paris 
White are excellent varieties of the cos type (also known 
as the Romaine). Hanson, Iceberg, and New York are 
well-known varieties of the solid, “crisp-head” lettuces. 
The butter varieties are well represented by Dutch But- 
ter, All Seasons, California Cream Butter, and Deacon. 
Big Boston is grown most largely as a head lettuce in the 
open ground. Other varieties valued for field planting 
are May King, All Heart and Wayahead. Grand Rapids 
is the most popular loose-leaved bunching variety grown 
in greenhouses, and Simpson outdoors. Green-leaved 
Big Boston (unrivalled) is a popular fall crop lettuce, 
and Salamander for summer use. 
There are over 125 distinct varieties of lettuce, which 
show the widest variation in size, color, solidity, texture, 
leaf-formation, flower, quality, disease resistance, tender- 
ness to heat or cold and time required to attain maturity. 
Probably the 5 best-known varieties in America are Big 
Boston, Black-Seeded Tennis Ball (Salamander), Han- 
son, New York (Wonderful), and Paris White. 
490. Climatic requirements.— Lettuce is a cool weather 
plant. It stands cold much better than heat. The 
tendency of many varieties is to produce seed shoots 
prematurely when an attempt is made to grow them in 
midsummer. The large markets are supplied by various 
regions which furnish the best conditions as the season 
advances and by the use of glass and artificial heat dur- 
ing the winter. When properly hardened the young 
plants will stand even lower temperatures than cabbage 
plants. A drop of 20 degrees below freezing will cause 
no injury if the plants have been fully hardened. The 
matured crop is more easily damaged by severe freezing. 
Notwithstanding the fact that lettuce is a cool weather 
plant, it is grown all summer in most parts of the North, 
due largely to the adaptation of varieties to various 
climatic conditions. The young plants are wintered 
