I’ve heard about gardeners being able to grow lettuce all summer, and now I guess I’m one of them.

I planted a large container of lettuce leaf ‘Salad Bowl Blend’ (from Botanical Interests) in spring. The seed packet did say it was one of the most heat tolerant and bolt resistant leaf lettuces available, but I didn’t expect that I’d still be using the tender leaves in my summer salads. Talk about cut and come again!

Granted, not every garden is going to have the same conditions for lettuce growing as I’ve had this summer. The weather in Denver has had its ups and downs all season. Days of 90 to 100 degrees have been followed by milder weather. 

However, lettuce growers in other parts of our region may benefit from the results of a 2004 Colorado State University study. Students in the Horticulture and Landscape Architecture group conducted The Lettuce Bolting Resistance Project and the results are really interesting. 

The project studied 50 different lettuce varieties that were planted every two weeks from June to September. The students prepared the fields and used organic methods to maintain the lettuce.

The weather during the project was unusually hot and dry with 26 days above 90 degrees. In addition, there was some insect damage to crops.

The research showed that Batavian lettuce varieties resisted bolting the best. These varieties didn’t bolt all season, even during the warmest weather. They could also be harvested at different stages during the growing season.

Nevada, Sierra and Tahoe were the standout cultivars.

The Butter varieties were the second-best lettuce group to hold reasonably well against bolting.

Red Romaine lettuces were found to be good for individual leaf harvest and baby lettuce production.

Perhaps you’ll want to conduct your own research to see which of these lettuce varieties resist bolting in your garden. There’s still plenty of time for planting this season.

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