Even though it still fees like summer, now is the time to start preparing for your fall garden. The first thing to keep in mind is the average first fall frost date. Once you know this date, it will guide you on when to plant your crops in your garden. According to this chart from NOAA, the average first frost date in Phoenix is around December 16th (I have found other charts ranging between December 1st to December 16th). If you are planning on planting broccoli, cauliflower, cabbage, or kale, those should be started indoors about 12 to 14 weeks before your first frost date. So for the Phoenix area, that’s now! We started broccoli, cabbage, baby bok choy, and brokali (broccoli and kale hybrid) last week and they have been germinating well. Here is a great guide from Mother Earth News on how to start seeds indoors.
When planting seeds directly outdoors, add 3 weeks to the days until maturity, then count back from your average first frost date. Each variety will have different days until maturity, so look on the back of your seed pack to determine when to plant. For example, we will be planting Sweet Treat Hybrid Carrots and Super Sugar Snap Peas from Burpee. Both varieties mature in 70 days. So that would mean we should direct-sow them in the garden around mid-September (70 days + 3 weeks = 91 days prior to the frost date). Vegetables like lettuce and spinach will not germinate in warm soil, so they should be sowed later around early to mid-October. We will be planing Little Gem Lettuce and Bloomsdale Long-Standing Spinach, both mature in about 45 days.
To get the garden ready, we have been removing all the plants from spring/summer and trying to get the grass under control. We have had perfect conditions for grass to grow, and it has been flourishing. The only crop we have left in the garden is our sweet potatoes, which should be ready in about a month.