The exception is one study in the Netherlandsâthe Netherlands Cohort Study on Diet and Cancerâin which women (but not men) who had a high intake of cruciferous vegetables had a reduced risk of colon (but not rectal) cancer (12).
Crops: beans, celery, corn, cucumbers, New Zealand spinach, and summer squash. Temperatures: Tender vegetables grow with daytime temperatures above 55Â°F, and are intolerant of frost. When to plant: 1  Based on soil temperature, refer to Table 2.2  Soil is adequately dry to work.3  These crops may be planted (from seed) around the date of the average last spring frost.emperatures: Very tender vegetables are not only intolerant of frost, but also cool spring winds. They need daytime temperatures above 60Â°F, and prefer temperatures of 70Â°F to 95Â°F. A week of daytime temperatures below 55Â°F may stunt the crop.
Plant when soil temperatures warm up to 35 to 40 degrees F. In general, cool season crops can be planted two weeks before the last frost date. Most cool season crops germinate at maximum soil temperatures of 90 degrees, except for lettuce and spinach, which require temperatures of less than 70 degrees.