Low Desert Arizona garden in September

What grows in low desert Arizona gardens in September? I’ll show you. All of these pictures come from my garden in Mesa, Arizona.
Low desert includes elevations below 3500 ft in the Southwest, such as the Phoenix and Tucson metro areas.
September! We’ve almost made it through the long hot summer. The good news – lots to plant this month in the garden. The bad news – the days are still hot. Even so, the mornings and evenings are beginning to cool off, reminding us why we love to live in Arizona!


Gardening in Arizona means there is something to plant or harvest year-round. Most vegetables can be grown in Arizona if they are planted at the right time, and for many vegetables, September is the right time. Prepare your Arizona garden in September for fall planting by amending it with compost and organic fertilizer.

Disclaimer: This post contains affiliate links. See my disclosure policy for more information.

Pests in the low desert Arizona garden in September
Unfortunately, the slightly cooler temperatures of September are inviting for pests. It is important to make efforts to prevent pests organically, but not all pests can be prevented. Be on the lookout this month for infestations in the garden. Read this article for organic pest control that really works.

Spider mites are a type of arachnid. Relatives of spiders and ticks, they can suck the life out of plants (literally).
Prune out large infestations, and spray off with water. Spray plants off with water regularly to prevent future infestations.

Tecoma plants, yellow bells, and bougainvillea often get infested with small caterpillars at this time of year. If the plant is large, it usually survives the infestation without affecting the tree’s overall health.
If you decide to treat, here are a few choices: spray off with water or use BT. When the weather cools a bit, the caterpillars will have moved on. Prune severely infected branches.

Whiteflies are active in the warm weather of late summer and early fall.
Aphids are most active in cooler weather.

What’s growing in the low desert Arizona garden in September?



September harvest picture: Edamame is finishing up, with lots of snake beans, a couple of monsoon-planted squash, cucumbers, and kale.

Keep up with daily okra harvests this month. Learn my seven favorite ways to use okra in this blog post.

Roselle blooms and harvests begin in earnest this month. Learn more about growing roselle in this article.

Peanuts may be ready for harvest this month.


Several types of winter squash grow well throughout September. Many will be ready to harvest next month.

Luffa fruit forms and grows quickly this month. Hand pollinate if female blossoms are not forming fruit. Learn how to grow luffa in this blog post.

Cucamelon vines thrive in September temperatures. Learn how to grow cucamelons in this blog post.


Which flowers are growing in the low desert Arizona garden in September?
September is a time of change in the annual flower bed. Clear out summer blooming annuals and amend beds well with compost. Once daytime temps are consistently below 100℉ (37.8°C) and nights cool down below 80°F (26.7°C) plant cool-season annuals from seed and transplants. Water newly-planted annuals each day until they show new growth and are established.

Blue Daze is an evergreen member of the morning glory family with blue flowers. This low-maintenance plant thrives in tree wells or containers.

Blackfoot daisy loves hot, dry conditions and does well in rocky areas. This low-mounding perennial gets about 2 feet wide and 1 foot high.

Gomphrena blooms steal the show this month. Learn more about growing gomphrena in this blog post.

Zinnias continue blooming through the next month or two. Learn how to grow zinnias in this article.

Collect seeds from blooming four o’clocks this month. Learn how to grow four o’clock flowers in this article.

Lisianthus blooms continue during September. Learn how to grow lisianthus in this article.

Sunset cosmos reseeds easily and blooms through the fall.

Vinca blooms well in Arizona gardens all summer long. It is one of 10 flowers that love hot summers.

Purple hyacinth bean vine blooms this month. This article shares how to grow purple hyacinth bean vine.

What’s happening with fruit trees in the low desert Arizona garden in September?

Lemons are beginning to ripen in September. Skin color is not always an indicator of ripeness, so taste the fruit to see when it is ready.
Fruit stores best on the tree. The longer the fruit stays on the tree, the sweeter the fruit becomes. Fruit will not ripen once picked. Ripe citrus fruit can be left on the tree for up to 6 months, depending on the variety.

Want to learn more about growing pomegranates? This article will help.

What’s happening with herbs in the low desert Arizona garden in September?

Basil is going strong. Continue to harvest to keep the basil from going to seed. Try one of my favorite ways to use fresh basil in this recipe. This article shares how to grow basil.

The oregano, mint, and other perennial herbs look haggard. Once temperatures dip below 100℉, trim them back by about 1/3 and feed with organic fertilizer and water well.

Garlic chive blooms are a sure indicator that it is September. The pollinators love the blooms. Learn more about growing garlic chives in this article.

Trim sage back by about 1/3, feed with organic fertilizer, and water well.
This article shares how to grow sage.
Arizona low desert garden in September to-do list:


- Prune summer-damaged perennial herbs back by about 1/3.
- Do not prune fruit trees this month.
- Fertilize citrus trees, if you didn’t do it in late August. Water citrus deeply this month, before and after fertilizing. Skip fertilizing grapefruit this time, they require less fertilizer than other types of citrus trees.
- Once daytime temperatures are consistently below 90℉ remove shade cloth (if using).
- Check your watering system, and fix any leaks. I use the watering grids from Garden in Minutes. Use code Angela10 to save $10 off $100
- When daytime temperatures are below 100℉, begin to adjust the time between watering citrus and other fruit trees to around twice a month. Water deeply but not as often as in the summer months.
- Clear out summer-blooming annuals and make room for cool-season flowers and annuals.
- Save seeds from zinnias and other summer flowers and vegetables.
- Find seed potatoes and begin the process of “chitting” them, so they will be ready to plant late this month or October. Learn more about how to grow potatoes in this article.
- Order garlic so you are ready to plant it in October. Store it in the fridge until it’s time to plant.
- Begin fertilizing roses again this month. Keep up with watering every few days until temperatures cool in October. Once temperatures are below 100℉, prune roses lightly to remove dead or diseased canes.
- Plant spring-flowering perennials this month.
- Plan your wildflower & winter flower garden.
- Refresh in-bed vermicomposting bins or start new bins when nighttime temperatures are consistently below 85°F.


What to plant in the low desert of Arizona in September

Before planting:
- Prepare beds for planting (this post tells you how). Top beds with Arizona Worm Farm Raised Bed Mix. Add compost, worm castings, and other organic matter to the soil.
- It’s important to have your soil tested at least once a year. A soil test can determine the health of your soil. I use this test kit from Amazon.
- Add a balanced fertilizer if needed.
Vegetables, herbs & fruit to plant in the low desert in September:

(Click the link to read “How to Grow” articles on my website.)
- Bean (Bush & Pole) (S)
- Cucamelon (T)
- Cucumber (ST)
- Eggplant (T)
- Ground Cherry (T)
- I’itoi Onion (bulb)
- Pepper (T)
- Potato (seed potato)
- Shallot (bulb)
- Summer Squash (ST)
- Tomatillo (T)
- Tomato (T)
After September 15 (or when nighttime temps are 70°F (21°C) or lower)
- Arugula (ST)
- Beet (ST)
- Bok Choy (ST)
- Broccoli (ST)
- Brussels Sprouts (T)
- Cabbage (ST)
- Carrot (S)
- Cauliflower (ST)
- Celery (T)
- Collard Greens (ST)
- Kale (ST)
- Kohlrabi (ST)
- Lettuce/Endive (ST)
- Mustard (ST)
- Onion (Green) (S)
- Parsnip (S)
- Peas (S)
- Radish (S)
- Rutabaga (S)
- Saffron Crocus (bulb)
- Spinach (ST)
- Strawberry (T)
- Swiss Chard (ST)
- Turnip (S)
SEED, TRANSPLANT, OR BOTH? S = Seed / T= Transplant

- PLANTING GUIDE: Each month lists vegetables, fruit & herbs to plant outside & seeds to start indoors.
- HARVEST GUIDE: Photos show what may be ready to harvest that month.
- Planting dates are for the low desert of Arizona (zone 9b).
Vegetable, herb & fruit seeds to start indoors in September

(Click the link for seed sources.)

Arizona Vegetable Planting Guide helps you learn when to plant vegetables in Arizona, and whether to plant seeds or transplants.
With 50 vegetables listed that grow well in the low desert of Arizona you are sure to find one to try.
Flowers to plant in the low desert Arizona garden in September:

(Click the link to read “How to Grow” articles on my website.)
- Baby’s Breath (ST)
- Begonia (T)
- Bells of Ireland (S)
- Dianthus (T)
After September 15 (or when nighttime temps begin to drop)
- African Daisy (S)
- Calendula (ST)
- Clarkia (T)
- Cornflower (S)
- Delphinium (S)
- Flax (S)
- Gaillardia (ST)
- Gazania (T)
- Larkspur (S)
- Linaria (S)
- Lobelia (T)
- Ornamental Cabbage/ Kale (T)
- Pansies (T)
- Petunia (T)
- Phlox (S)
- Saffron Crocus (bulb)
- Salpiglossis (T)
- Salvia (T)
- Snapdragon (T)
- Verbena (T)
SEED, TRANSPLANT, OR BOTH? S = Seed / T= Transplant
Flower seeds to start indoors in the low desert in September

(Click the link for seed sources.)
Perpetual Flower Planting Calendar is available in my shop

Flowers to Plant Outside & Seeds to Start Indoors Each Month in the Low Desert of Arizona.
• PLANTING GUIDE: Each month lists annual flowers and bulbs to plant outside & seeds to start indoors.
• BLOOMING GUIDE: Photos show what may be in bloom that month.

Arizona annual flowers planting guide helps you learn when to plant flowers in Arizona, and whether to plant seeds or transplants.
Seed Box Labels with planting dates for vegetables and flowers




Want more information about gardening in Arizona? This blog post shares 7 tips for how to grow a vegetable garden in Arizona.
If this post about Arizona gardening in September was helpful, please share it:



Denise Marie
Thursday 31st of August 2023
I am compelled to ask what kind of flowers those are (pink with red centers) in the first picture on this post please? And, are they heat tolerant? They ARE incredibly beautiful!
Thank you!
Angela Judd
Thursday 31st of August 2023
Those are roselle hibiscus flowers. I agree they are beautiful. You can learn more about growing roselle here: https://growinginthegarden.com/how-to-grow-roselle-hibiscus-growing-jamaican-sorrel/
Rose
Monday 28th of August 2023
I would like to know what flowers to plant in September, these suggestions appear to be flowers that should have been planted in the spring for September blooms. What to I plant now for future blooms is my question?
Angela Judd
Monday 28th of August 2023
Keep reading to the end of the post. At the end of the blogpost I list all the flowers to plant outside and which ones to start inside during the month of September.
Joy
Sunday 19th of September 2021
I just moved here from Alaska and have been watching your videos and reading your blog to learn about gardening here. Where do you usually buy your seeds from? In particular, seed potatoes?
Angela Judd
Sunday 19th of September 2021
Welcome to Arizona! Seed potatoes are tricky because they are often not available when it is time for us to plant. I often sprout ones I purchace from Sprouts or another grocery store. My favorite seeds are from Botanical Interests. You can find them at local nurseries or online. If you purchase them through this link:https://shareasale.com/r.cfm?b=250954&u=2736599&m=28945&urllink=&afftrack= I receive a small commission.
Melana
Wednesday 1st of September 2021
I am so trying to learn to garden here in Tucson. We moved from Missouri where I had to hide veggies in the neighbors mail boxes I grew so much. I straw bale gardened there. However, I have not been able to grow a bloody thing here with the exception of 1 banana pepper that I finally threw in the backyard to "die". It lived so I figured if it was that much of a fighter I'd fertilize it and give it some water. Gardening here has been abysmal at best....I planted according to your August schedule in new raised bed garden plots with good organic soil and most all of it never even came up. Broccoli, Kohlrabi, celery, cabbage, beets, carrots...nada, zip. I fully realize there is "no crying in gardening" but I'm about at the end of my hoe with trying here! I will give it another whirl this month and see if anything comes up....after that, I think I'll just throw in my hoe.....
SonoranDweller
Sunday 17th of September 2023
@Melana, We’re here in Tucson and have had plenty of success. Plenty of failure too. Please don’t give up. The extension at the Tucson Village Farm on River and Campbell is an amazing resource. And plant spaghetti squash. Much love and luck.
Angela Judd
Friday 3rd of September 2021
Sorry to hear that. Sounds like you are on the right track. Fall gardening can be much more rewarding than gardening when it is so hot. I hope things improve for you soon. May the gardening odds be ever in your favor.
Jennifer Lewis
Friday 27th of September 2019
This was such a hot summer! None of my tomatoes survived either. I have fingers crossed and hoping cooler weather gardening may be more successful for me this year! How exciting about your new build, congratulations!! I'm newly moved to Tucson, and learning how to garden in this weather. Loving it so far!