Summer Lettuce
There is a significant amount of literature about lettuce cultivars (cultivated varieties) that do well in the summer heat.
One paper out of Auburn University (in SOUTHERN Alabama) states
Cultivars ‘Aerostar’, ‘Monte Carlo’, ‘Nevada’, ‘Parris Island’, ‘Rex’, ‘Salvius’, and ‘Sparx’ performed well in a hot greenhouse and were preferred by consumers (for flavor).
Another paper out of Purdue (southern Indiana) states that the following varieties are suitable for summer harvest
Bibb: Bambi, Deer Tongue (specialty)
Butterhead: Adriana, Nancy, Pirat, maybe Sylvesta.
Leaf: Tropicana, Panisse (specialty), Green Star.
Romaine: Aerostar, Coastal Star, Freckles (specialty), Green Forest, Green Towers,
Salvius. Summer Crisp: Nevada.
with Green Forest head-and-shoulders above the others in terms of marketable weights.
Winter lettuce differs from summer-lettuce cultivars because the newer, day-neutral cultivars that do well in the summer are daylength neutral. They tend to bolt at 65 days regardless of heat units and daylength (although drought can tip them into early bolting). All lettuce becomes bitter when it bolts.
The issue with fall and winter is that the plant grows slowly and will be tiny at 60 days. One could plant thickly and harvest as mini-greens but the leaves can be little-fiddly things to wash.
Older cultivars without the daylength-neutral genes will hold for 112 days (or more) without bolting under six hours of light a day which allows them to both size-up more and to "hold" in the greenhouse bed until the cook is ready to harvest them.
Unfortunately, sellers of lettuce seeds do not specify whether varieties marketed as "winter" lettuces have or do-not-have the daylength-neutral genes. Lettuces like "Winter Density" and "Rouge D'Hiver" have names that imply that they do well in the late-fall and winter but words are cheap.
What do you guys with greenhouses (Howard? Anybody else?) have to say about lettuce cultivars to stretch out the season into the short days of fall and winter? Any favorites?
Monte Carlo, Adriana and Green Forest were the three primary varieties I grew in my hydroponic green house and grow room. We consistently harvested on average 600#/week year round with a six week growing cycle - Lou
ReplyDeleteI usually plant some early lettuce here in Copper Basin Alaska transplanted to some 2 foot square pots in Early May. Costal Star and Adriana have worked ok. With our extreme June /July day length (essentially it doesn’t get dark between June 10 and July 10. We are down to a couple hours dark now. We are loosing light quickly after the equinox and we occasionally have single digit temps by October 1 so it is not worth burning fuel to extend the season much beyond the equinox. We don’t do much summer lettuce because my family tends toward dipping vegetables like broccoli, cauliflower, kohlrabi, cucumbers, carrots and tomatoes all eaten raw dipped in dressing of their choice so I try to schedule planting for harvest fairly steadily with as much variety as possible. Right now my challenge is to get sufficient water on the hoop houses and green house. We have had a week of 75 to 80 highs lots of sun and another week in the forecast at those temps. The buildings are running high 90’s to 100 so the plants are using a lot of water. Our potato ground is the only outdoor garden this year as the garden area where I would have planted an assortment including peas, beets and all of the cole crops succession planting was still too wet to work July 4! Definitely a challenging year!
ReplyDeleteThere are a lot of really good You Tube videos on very simple container hydroponic systems that are low maintenance that would provide winter lettuce.
ReplyDelete> Purdue (southern Indiana) - Purdue is in W. Lafayette - Northern Indiana.
ReplyDeleteI stand corrected.
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