Growing Lettuces Outdoors and under Glass
By
S. O. GILLARD,
Vegetable Instructor, Department of Agriculture,
Auckland
LETTUCE is probably the most popular salad vegetable in New Zealand and is particularly welcomed in spring and early summer after a succession of winter vegetables. In the Auckland area where suitable climatic conditions prevail lettuces can be produced outdoors all the year round, although peak production is in early summer. Lettuce culture has become common among all commercial vegetable growers, because being a short-term crop lettuce is often a very convenient “filler” between two main crops of other vegetables.
LETTUCE (Latusa sativa) is a native of India and Central Asia and its present-day excellence is far removed from its original state. Although it is most easily grown in spring, good crops can be produced outdoors throughout the year in' favourable localities around Auckland. Possibly the most difficult period in which to grow firm-headed lettuce is late summer. Most firm-headed varieties require a relatively low summer temperature, particularly during the last period of growth. With high temperatures the tendency .to “bolt” is greatly accentuated; bolting is the rapid elongation of the seed stem and causes the separation of the leaves and consequently only a loose head to form. If bolting begins at an early stage, it may prevent the formation of a hearted head. Soil Conditions Although lettuce has a high moisture requirement, it is intolerant of very high soil-moisture content. Soils selected for lettuce culture should be friable; it is important that they do not pack after rain nor crack in dry weather. Soils for winter culture should be sufficiently open textured to facilitate the rapid dispersal of winter rains. To be succulent, lettuce must be kept growing rapidly and a good
rich loam is to be preferred to poor soils which require heavy dressings of fertiliser. Lettuce is one of the most sensitive of vegetables to soil acidity, and manyinstances of crop failures can be traced to high acidity. A near-neutral but not alkaline soil is best and applications of lime may be necessary to correct acidity where it is considered to be excessive. Varieties Of the varieties of lettuce commonly grown in commercial gardens in Auckland the following are most popular:— Neapolitan, also known as Webbs Wonderful, and New York. This favourite variety produces large crisp, firm heads and crinkled leaves of good colour. Special selections have been made for summer and winter production and are known as Neapolitan Summer Market and Neapolitan Winter Market. Imperial: The Imperial types of lettuce are now well known among producers. Among the more popular are: — Imperial 615, which has a semiexposed heart, is slightly flat on top, and is very firm at maturity. It is a large, spreading variety with numerous wrapper leaves and does best in cool weather, but is adaptable to a
wider range of conditions than the other strains of Imperial. Although good crops of 615 have been harvested in summer, it is inclined to bolt and summer-produced heads are somewhat coarse. The leaves are subject to tip burn in hot weather. Imperial 847 is recommended for summer and autumn production. Heads, which are smaller than those of 615, are round and well folded and hearts are semi-exposed at maturity.' It is of good quality and resistant to tip burn. Imperial 44 is suitable for summer production. It has well-shaped, compact heads, but is not as popular as 847. Imperial D: Recommended for production in the cooler months, this variety is more subject to tip burn in hot weather than other Imperial strains. Heads are well shaped, very compact, and firm and usually larger than Neapolitan. Leaves are dark green, and the heart is well bleached and crisp. It is a good-flavoured lettuce. Iceberg is one of the largest-headed varieties. It will stand longer than most varieties after hearting without running to seed head. The outer leaves are dark green with slightly bronzed edges. Hearts are large, firm, crisp, and well bleached. The variety is recommended for summer production and withstands dry weather better than most varieties. Great Lakes: A recent introduction of the Imperial type, this variety is very suitable for summer production, being resistant to tip burn. It is large and vigorous, with good, firm heads which hold well even in hot weather. Leaves are almost smooth with serrated edges, and there are few wrapper leaves. This variety will probably increase in popularity for
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Bibliographic details
New Zealand Journal of Agriculture, Volume 82, Issue 6, 15 June 1951, Page 497
Word Count
735Growing Lettuces Outdoors and under Glass New Zealand Journal of Agriculture, Volume 82, Issue 6, 15 June 1951, Page 497
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