Evaluating Extended Season Head Lettuce Production in West Virginia

Lettuce (Lactuca sativa L.) is a high-value crop for many retail and wholesale markets in West Virginia.  Lettuce is a cool season crop, yet it may be possible to grow a head lettuce crop year-round in the Mid-Atlantic region using a combination of suitable genotypes and season extension technology. The objective of this comprehensive lettuce evaluation was to examine heat and cold tolerance of diverse bibb and select romaine lettuces within West Virginia during 2012 using low and high tunnels for extended season production. Lettuce seed of 30 cultivars was acquired from several cooperating seed companies and seeded for transplants on 3 April, 3 July and 25 September 2012.   Plugs were hand-transplanted into rows on black or white plastic mulch within a high tunnel on 5 May, 6 August, and 7 November 2012.  The high tunnels were located in central West Virginia (37°N lat.)   Each mature head was weighed and head diameter recorded. Bolting, flavor and tip burn incidence were noted for each variety. Shade cloth (≈50% black) was used for mid-summer lettuce production of select varieties. Row covers were used for winter high tunnel production.   Storage quality of washed and unwashed bibb and romaine lettuce was also evaluated in September. Economic analysis of extended season lettuce production was conducted. The 2012 growing season had record high temperatures and was the warmest summer on record in West Virginia. The following lettuce cultivars performed very well across all planting dates:  ‘Australe’, ‘Buttercrunch’, ‘Coastal Star’, ‘Dancine’, ‘Helvius’, ‘Nancy’, ‘Nevada’, ‘Regina delle Ghiacciole’, ‘Rex,’ ‘Rouge Grenoblois’, and ‘Sierra’.   ‘Parella Rosa’, ‘Passion Brune’, ‘Brune D’Hiver’, ‘Regina di Maggio’, and ‘Quatro Staggioni’ were not heat tolerant lettuce cultivars and bolted rapidly during the summer heat.  Butterhead and romaine lettuce which was washed in chlorinated water and stored at 2 °C had excellent quality for more than 16 days.  Head lettuce is a 60–80 day maturity crop depending on the season of the year.  Thus it is possible to have as many as four lettuce crops per year in West Virginia.   Estimates of profitability have shown lettuce can produce a net return of $1600–2700 per 1000 ft² within a high tunnel.  A commercial high tunnel with approximately 2800 ft² could produce as many as 5400 single heads of lettuce per crop cycle.