What to Plant in September in Arizona

September in Arizona’s low desert signals the shift from summer’s intense heat to slightly milder days, making it an ideal time to refresh your garden. The sun’s angle is changing and lowering. While the temperatures are still warm, the cooler mornings and evenings provide a perfect window for beginning the transition into fall and winter planting. This article will explore what to plant and the possible harvests in September.

Read “Arizona Garden in September ” for a printable checklist and information about September gardening tasks for the low desert.

The low desert includes elevations below 3500 ft in the Southwest, such as the Phoenix and Tucson metro areas.

---

Article Outline:

• What to Do Before You Plant In September
• What Can You Harvest in September in The Low Desert?
• What’s Blooming in September?
• What to Plant Outside in September in Arizona: Vegetables, Herbs & Fruit
• Which Seeds to Start Indoors in September in Arizona: Vegetables, Herbs & Fruit
• What to Plant Outside in September in Arizona: Flowers
• Which Seeds to Start Indoors in September in Arizona: Flowers

---

---

What to Do Before You Plant During September in Arizona

As you decide what to plant in September (and upcoming months) in your low desert garden, think about what you enjoy growing the most—which cool-season crops do you most look forward to in the garden? Which foods taste best from the garden? What do you love having easy access to? Mid-September and October are prime cool-season planting months.

• Prepare beds for planting (this post tells you how). Add compost, worm castings, and other organic matter to the soil.
• If you’re not going to plant for at least a month, then plant a last round of cover crops–black-eyed peas early in the month or buckwheat later in the month. The plants don’t have to get very large before they are chopped and used as organic matter to benefit your soil.
• If your garden hasn’t been growing well, consider having your soil tested. I use this test kit from Amazon. Based on the soil test, add a balanced fertilizer if needed.  
• Take time to harden off your seedlings correctly so they can adjust to the heat. Learn more in this article.
• Provide extra shade and water for new plantings.

Want more information about gardening in Arizona? This blog post shares seven tips for how to grow a vegetable garden in Arizona. 

---

What Can You Harvest in September in the Low Desert of Arizona?

---

Many warm-season crops shine in September, with slightly cooler and shorter days. Okra and luffa, in particular, are productive. Keep okra harvested to keep it producing. Luffa can be eaten when harvested very young, but you’re probably growing it for the sponges it produces. These can take a few more months to fully develop, be patient!

We can garden year-round here in the low desert, and it seems there is always something to plant and harvest. If you’re following my planting guide, here are some of the vegetables you might be harvesting during September. I’d love for you to leave a comment and let me know what you’re harvesting right now.

(click on the link to read “How to Grow” articles about each crop)

Vegetables:

Amaranth, Armenian Cucumbers,  Asparagus Beans, Beans, Borlotti Beans, Butternut Squash, Cucumbers, Eggplant, Malabar spinach, Okra, Peppers, Sesame, Sunflower Seeds, Summer Squash, Tomatillos, Tomatoes 

Herbs:

Basil, Lemongrass, Oregano,  Sage, Stevia, Rosemary, Thyme

Fruit:

Cantaloupe, Chichiquelite, Figs, Ground Cherries, Watermelon

---

What’s in Bloom in September in the Low Desert of Arizona?

September marks a transition in the garden. Summer’s vibrant blooms continue while the first fall flowers start to appear, adding new color and texture to the landscape.

(Click on the link for each flower’s “How to Grow” blog post.)

Possible blooms this month include amaranth, angelonia, basil, celosia, coreopsis, cosmos, four-o-clock, gaillardia, garlic chives, gazania, gomphrena, lisianthus, luffa, mahogany splendor hibiscus, portulaca, purple hyacinth bean vine, roselle hibiscus, rudbeckia, salvia, statice, sulfur cosmos, sunflower, tithonia, verbena, vinca, and zinnia.

---

What to Plant Outside in September in the Low Desert: Vegetables, Herbs & Fruit

When planting, take care with transplant stems. Handle by roots or leaves; they can grow more of both. Damage to the stem can be fatal to the plant.

(Click the link to read “How to Grow” articles on my website.)

All month long:

*After September 15 (or when nighttime temps begin to drop)

SEED, TRANSPLANT, OR BOTH? S = Seed / T= Transplant

Pay close attention to the weather this month. If temperatures are still in the 100s and the nights are still hot, wait to plant cool-season crops. A soil thermometer is helpful. If the soil temperatures are at or above 85°F, the soil is still very warm–wait to plant. Seeds like lettuce and cilantro need cooler soil. Learn how to check the soil temperature in this blog post.

Arizona Vegetable Planting Guide helps you learn when to plant vegetables in the low desert of Arizona and whether to plant seeds or transplants.

---

Which Seeds to Start Indoors in September: Vegetables, Herbs & Fruit

(Click the link for seed sources)

Here’s a link to my favorite seed-starting supplies on Amazon.

---

Flowers to Plant Outside in September in The Low Desert

(Click the link to read “How to Grow” articles on my website.)

All month long:

After September 15 (or when nighttime temps begin to drop):

SEED, TRANSPLANT, OR BOTH? S = Seed / T= Transplant

---

Flower Seeds to Start Indoors in September

(Click the link for seed sources)

Arizona Annual Flowers Planting Calendar helps you learn when to plant flowers in Arizona and whether to plant seeds or transplants.

---

Make plans for planting roses next month. Choosing the right varieties helps ensure your roses survive the summer heat. Roses such as Memorial Day, Iceberg, Mother of Pearl, and Julia Child are excellent choices as they are known for their resilience and ability to withstand high temperatures.

I get all of my roses from Heirloom Roses. I love that they are own-root roses (no grafts!) and have the highest standards for diseases. You know you are getting robust, disease-free roses with strong roots when you get them from Heirloom Roses. Use Code GARDENAZ20 for 20% off any rose order through December 31, 2025. Order now and have them shipped when you are ready to plant (up to 8 months later).

---

If this post about what to plant in September in Arizona was helpful, please share it.