Vegetables are divided into two groups warm season and cool season. Cool season vegetables, like their name implies, thrive when planted so they mature when temperatures are cooler.
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In gardening zone 9b this means they should be planted at the end of summer or fall.
Cool season veggies can tolerate short term frost, so if the weather dips in January for a short period of time your cool season veggies will be ok. Cool Season vegetable seeds can germinate in 40 degree soil. They prefer soil temps between 60-80 degrees. They do best when the minimum day temperature is between 40- 50 degrees.
Grow Cool Season Vegetables in Phoenix Gardening Zone 9b
Visual guide to planting cool season vegetables and fruits in your Phoenix garden zone 9b. Some of our favorite cool season vegetables include: broccoli, carrots, onions, radishes, lettuce, and snap peas.
Plant Broccoli August 15 – January 15
Plant Carrots August 15 – April 15
Plant Lettuce August 15 – February 1

Grow Lettuce
Plant Peas September 1 – February 15
Plant Onions August 1 – April 15

Grow Onions
Plant Radishes September 1 – April 15
Plant Beets