The Q&A Archives: When to Start Vegetable and Flower Seeds

Question: When should you start vegetable and flower seeds and plant them for Yuma, AZ? The temp now is still 105-110 during the day. Also, can bulbs ever be planted here?

Answer: There are two distinct growing seasons in the low desert with different annuals thriving in each season. There's a cool season from approximately the end of September through April. Annuals can be installed from late September to February. Some gardeners prefer to wait until October, as cooler temperatures are less stressful and less water is needed. Also, cool temps. help kill off whitefly populations which can quickly decimate plants.

A rule of thumb for cool-season vegetables is that we eat parts of the plant itself, such as leaves (lettuces/greens), stems (kale, broccoli and other cole crops) and roots (beets, carrots, turnips, onions). (In the warm season, we eat the seeds and fruits (tomatoes, peppers, cukes). The major exception is peas. Although we eat the seeds, we plant them in the cool season. Root crops do best if sown in place, rather than transplanted. Cole crops do well as transplants. I find leafy crops can go either way, but sowing in the ground seems easier to me, since thinning can be used in a salad!

Lots of flowers can be planted for enjoyment from late September through April. Some of my favorite easy-to-grow annuals include calendula, bachelor's button, pansies and violas, nasturiums, stock, snapdragons, alyssum, dusty miller, poppies and dianthus to name a few. Wildflowers are also seeded in the fall for spring bloom. October is a good month for that.

The warm season starts with planting in mid to late February. Some plants will make it through the summer's heat; others will end their growth when the heat arrives in May or June. Warm-season annuals include sunflowers, tithonia, zinnia, coreposis, cosmos, gaillardia, black-eyed Susan, coneflower, lisianthus, and vinca.

You can start seeds indoors about 6 to 8 weeks before planting them out, although some do better if sown directly, such as root crops and wildflowers. You can download two publications from the University of Arizona Cooperative Extension that contain planting calendars. Go to Input vegetable, gardening/hort, and publication in the fields. Do the same for flower. You can also subscribe to the National Gardening Association's free Southwestern garden feature which contains bi-weekly reminders of gardening tasks. Go to and click on the Southwest.

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