Spinach is a cool-weather crop that thrives in temperatures between 35°F and 75°F. When temperatures rise above 75°F, especially in June, spinach plants tend to bolt, which means they quickly develop a flower stalk.
Lettuce, particularly varieties like butterhead, romaine, and leaf lettuce, prefers cool weather. When exposed to high temperatures in June, lettuce plants bolt. Bolting in lettuce results in the formation of a central stalk that grows taller and produces flowers.
Arugula, also known as rocket, is another leafy green that prefers cooler temperatures. When the weather warms up, arugula plants quickly bolt. Bolting causes arugula leaves to become overly spicy and bitter.
Radishes are root vegetables that mature quickly in cool weather. In hot conditions, especially those in June, radishes can become woody and develop a strong, pungent flavor.
Broccoli plants prefer cooler temperatures and often struggle to form tight, compact heads when it s too warm. In June, rising temperatures can cause broccoli to bolt, producing loose, flower-like structures instead of the desired heads.
Cauliflower is sensitive to heat and requires consistent cool temperatures to form dense, white heads. When exposed to high temperatures in June, cauliflower can become discolored and develop a loose, grainy texture.
Cilantro, or coriander leaves, bolts quickly in warm weather, often seen in June. When cilantro bolts, it sends up a tall flower stalk, and the leaves become sparse and develop a soapy taste.
Peas thrive in cool, moist conditions and tend to stop producing flowers and pods as temperatures rise in June. The quality of the peas declines in the heat, with pods becoming tough and starchy rather than sweet and tender.
Chard is somewhat more heat-tolerant than other leafy greens, but prolonged exposure to high temperatures in June can still cause the leaves to become tough and fibrous.