Fall Gardening in Arizona: Tips for Success

As summer ends, so does the growing season for many areas, but not for the low desert of Arizona. Fall gardening in Arizona brings welcome relief from the intense summer heat and ushers in a favorite time for gardeners. The cooler months ahead offer countless possibilities. Here’s how to make the most of them. 

Article Outline:

1. Maximize Sunlight in Your Fall and Winter Garden
2. Evaluate Existing Crops
3. Prepare Your Garden Beds
4. Choose and Plant Crops
5. Transition Your Watering Schedule
6. Monitor for Pests

1. Maximize Sunlight in Your Fall and Winter Garden

Selecting the right location is crucial for a successful fall and winter garden. The sun’s position changes with the seasons, affecting how much sunlight your garden receives.

In summer, the sun is nearly overhead at midday, providing maximum garden sunlight. However, in winter, the sun is lower on the horizon, which may result in previously sunny areas receiving little to no direct sunlight due to shadows cast by buildings, fences, and trees.

During spring and autumn, the sun’s midday position is between its high summer peak and low winter angle, offering moderate sunlight compared to the extremes of summer and winter.

Understanding these changes can help you better plan where to place your garden. Your garden should receive 6-8 hours of sunlight daily if possible.

Shady areas with less than ideal sunlight are good places to plant leafy vegetables like spinach, lettuce, and kale. These plants require the least sun. If the sunlight is less than ideal, allow plenty of space between plants to maximize the sunlight they receive. Overplanting will exacerbate the lack of sunlight, making plants more likely to struggle. 

Practical Tip: Observe your garden’s sunlight patterns to identify the best spots for your fall crops. A garden journal can help track sunlight exposure throughout the day. If you have shade cloth up for summer, take it down once daytime temperatures are consistently below 90°F (32°C).

2. Evaluate Existing Crops

Because we can garden year-round in the low desert, our garden beds are often full of different vegetables, herbs, and flowers at different stages. That’s ok! As we transition to a new season, evaluate each plant to decide if it is staying put or you are taking it out.

Here’s what to consider:

• Is it healthy and disease-free? 
• Is it producing well, or is production slowing down? 
• Are you sick of eating it? 
• Do you want the spot for something else? 

Use your answers to these questions to decide whether it’s time to remove the plant or leave it in place.

It’s possible to overwinter many warm-season crops like tomatoes, peppers, and eggplants. You’ll need to cover them if we get a freeze. However, other warm-season crops like beans, cucumbers, and melons will not tolerate cold temperatures. Allow those crops to finish producing and remove plants as they finish up. Remember, cutting crops off at the soil level is the least disturbing to the soil and is recommended for everything but diseased or pest-infected crops. 

Practical tip: Pepper plants can live for several years. Production can slow after about three years. Peppers benefit from occasional pruning. Learn more about pruning peppers in this blog post.

3. Prepare Your Garden Beds

Before fall planting, it’s essential to refresh your garden beds. Begin by adding worm castings.  Apply 1 pound (approximately 453 grams) of worm castings per 40 square feet (about 3.72 square meters) for existing raised garden beds. The easiest and most economical way to ensure a steady supply of worm castings for your garden beds is to add in-bed vermicomposting bins. Learn more about how to add vermicomposting bins to your beds in this blog post. 

Much of the organic matter in your soil likely decomposed over the summer. Replenish it by adding compost to fill your beds. Aim to add at least one inch of compost to each bed. This not only adds nutrients but also improves soil structure and moisture retention. For more information about preparing soil before planting, read this article.

Amending soil in beds that already have plants can be challenging. If your beds contain plants you plan to overwinter, carefully pull back the mulch and apply compost and worm castings around these plants. For areas with plants nearing the end of their life cycle, hold off on amending the soil until these plants have finished. After removing the spent plants, you can amend the soil in these areas.

If you are gardening in containers, read this post for details about amending your container garden soil.

Practical tip: To add a 1-inch (2.54 cm) layer of compost to a 4×8 foot (1.2×2.4 meter) bed, you will need about 2.67 cubic feet (approximately 75.6 liters) of compost.

For a 4×8 foot bed (1.2×2.4 meters), you’ll need approximately 0.8 pounds (about 360 grams) or roughly 1.6 cups of worm castings to adequately enrich the soil. Learn more about the benefits of worm castings in this blog post.

4. Choose and Plant Crops

Use the monthly planting guides and prioritize the crops you want to grow in your fall garden. Interplant cool-season crops in the shade of warm-season crops while they finish up. As you plant, leave a few empty spots in each bed to add cool-season companion plants.

Monitor temperatures closely—delay planting cool-season crops if daytime highs are still in the 100s or if soil temperatures exceed 85°F. Read this post to learn more about the importance of soil temperatures.

Here are key tips for planting cool-season crops successfully when it’s still warm (hot):

• Plant seeds a little deeper to keep them cool.
• Take time to harden off indoor grown seedlings, gradually exposing them to outdoor conditions, starting with morning light.
• Reduce transplant shock by planting during cooler evening hours.
• Provide shade and apply mulch to protect young plants and maintain soil moisture.
• Increase watering frequency to match the hot conditions, ensuring the soil remains moist but not waterlogged.

Practical tip: Monitor your seedlings when you are hardening them off. If they aren’t tolerating it well, there’s no need to force it. Wait another week, let temperatures decrease a little more, and then try again. Learn more about how to harden off plants here.

5. Transition Your Watering Schedule Throughout Fall

While it’s still warm, your garden will need more water, but the watering needs will drop significantly as the days get shorter and the nights get cooler. Pay attention to your soil and gradually lengthen the time between watering. 

Fall gardening in Arizona is a time of transition. As fall progresses, watering may go from every 2 days to once every 4-5 days or longer. Monitor your soil closely to prevent overwatering. Too much water causes slow growth in plants. 

Practical Tip: Newly planted seeds and transplants must be kept hydrated, so you may find yourself hand-watering more often.

I use the garden grids from Garden in Minutes to water my raised beds. Use code Angela10 to save $10 off $100 or GITG5 to save 5 percent on any size order.

6. Monitor Your Fall Garden for Pests

Even in cooler weather, pests like aphids, whiteflies, and cabbage worms can still pose a threat. Daily observation will help you be aware of what is happening. If warm-season crops become infested, that is a sign that it’s time to remove them from the garden. 

Prevention Focus: Healthy plants are less likely to attract pests. Keep your plants watered correctly and adequately spaced to maintain their vigor.

Fall gardening in Arizona is a rewarding endeavor that extends your growing season and maximizes your garden’s potential. You can enjoy a bountiful harvest throughout the cooler months by carefully selecting crops, preparing garden beds, and adjusting care routines. Keep an eye on the weather, follow these tips, and your garden will thrive this fall. 

Sources:

• The sunlight infographic is patterned after the sun position infographic on this page: https://deepgreenpermaculture.com/2020/03/24/emergency-survival-prepper-vegetable-gardening-part-1-selecting-a-location-for-a-food-garden/

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