When To Plant Potatoes In Arizona

Figuring out when to plant potatoes in Arizona is the first step to a successful harvest. Our unique climate, with its hot summers and mild winters, means your timing has to be just right.

If you plant too early or too late, the heat can ruin your crop. But get it right, and you’ll be rewarded with homegrown spuds that taste amazing. This guide will walk you through the best planting windows for each region and give you the tips you need to grow potatoes like a pro in the desert.

Unlike most of the country, Arizona has two main potato planting seasons. The key is to avoid the extreme summer heat, which potatoes really don’t like. Your planting time depends entirely on where you live in the state.

Understanding Arizona’s Growing Zones

Arizona isn’t just one climate. It’s split into distinct zones that affect your gardening calendar.

Low Desert (Zones 9a-10b): This includes Phoenix, Tucson, and Yuma. Summers are extremely hot and long, winters are very mild.
High Desert (Zones 7b-8b): This includes Prescott, Kingman, and parts of Payson. Summers are warm but nights are cooler, and winters see frost.
Mountain Regions (Zones 6a-7a): This includes Flagstaff, Show Low, and Alpine. Summers are short and pleasant, winters are cold with heavy frost and snow.

Best Planting Dates by Region

Here’s your regional calendar for potato planting. These dates are your best starting point.

For the Low Desert (Phoenix, Tucson, Yuma)

You have a primary and a secondary season. The fall planting is often most succesful.

Fall Planting (Primary Season): Plant from late August through September. The goal is to have your potatoes growing through the fall and into winter, maturing before the summer heat returns.
Spring Planting (Secondary Season): Plant in mid-January through early February. This is trickier, as the plants must mature before the June heat hits.

For the High Desert (Prescott, Kingman, Payson)

Your window is centered on spring, after the last frost.

Spring Planting: Plant from mid-March through April, once the danger of a hard frost has passed. The soil should be workable and starting to warm.

For the Mountain Regions (Flagstaff, Show Low)

You have a short, classic summer growing season.

Spring/Summer Planting: Plant in late April through May, after all frost is gone. You want to harvest in early fall before your first frost arrives.

Choosing the Right Potato Varieties

Not all potatoes are created equal, especially for Arizona. You need varieties that mature quickly to beat the heat.

Early Season Varieties (60-80 days): These are your best bet. Look for ‘Yukon Gold’, ‘Red Norland’, ‘Irish Cobbler’, or ‘Mountain Rose’. They mature fast.
Mid-Season Varieties (80-100 days): Can work in the low desert fall plantings or high desert springs. Try ‘Kennebec’ or ‘Purple Majesty’.
Late Season Varieties (100+ days): Generally not recommended for most of Arizona due to our heat.

Always buy certified disease-free seed potatoes from a garden center. Don’t use potatoes from the grocery store, as they are often treated to prevent sprouting.

How to Plant Your Potatoes: A Step-by-Step Guide

Follow these steps for a great start. Proper planting sets the stage for the whole season.

Prepare the Seed Potatoes: A week or two before planting, set your seed potatoes in a warm, bright place to encourage short, sturdy sprouts (this is called “chitting”). A day before planting, cut larger seed potatoes into pieces, ensuring each piece has at least 1-2 eyes. Let the cut pieces dry to form a callus.
Choose and Prepare the Site: Potatoes need full sun (at least 6-8 hours). They prefer loose, well-draining soil. Amend Arizona’s native clay soil with plenty of compost. Avoid fresh manure, which can cause scab disease.
Planting Method:
- Dig a trench about 6-8 inches deep.
- Place seed pieces cut-side down, 12 inches apart.
- Cover with 4 inches of soil.
- Space rows about 2-3 feet apart.
Watering: Water deeply at planting. Then, maintain consistent moisture. Potatoes need about 1-2 inches of water per week. Inconsistent watering leads to knobby or hollow potatoes.

Caring for Your Potato Plants

Ongoing care is simple but crucial. The main tasks are hilling and pest watch.

The Importance of Hilling

As your plants grow to about 6-8 inches tall, gently mound soil around the stems, leaving just the top few leaves exposed. This is called hilling.

It protects developing tubers from sunlight, which turns them green and toxic.
It encourages more potatoes to form along the buried stem.
Repeat hilling every few weeks as plants grow.

Fertilizing for Success

Potatoes are moderate feeders. Mix a balanced, slow-release fertilizer into the soil at planting. When plants are about a foot tall, you can side-dress with a low-nitrogen fertilizer to support tuber growth. To much nitrogen makes leafy plants with few potatoes.

Pest and Problem Watch

Arizona gardeners face a few specific issues.

Colorado Potato Beetle: Less common here but possible. Hand-pick them off.
Aphids: Blast them off with a strong stream of water.
Heat Stress: If a spring heatwave hits, use shade cloth to protect your plants.
Overwatering: Can cause tubers to rot. Ensure excellent drainage.

Harvesting and Storing Your Bounty

Knowing when and how to harvest ensures your potatoes store well.

When to Harvest

You can harvest “new” potatoes when plants flower. For full-sized, storage potatoes, wait until the plant tops (vines) turn yellow and die back completely. This is a sign the tubers have matured. Stop watering about two weeks before your planned harvest to toughen the skins.

How to Harvest

On a dry day, use a digging fork to gently loosen the soil several inches away from the plant.
Lift the plant and carefully sift through the soil for all the tubers.
Be gentle to avoid bruising or cutting the potatoes.

Curing and Storage

Don’t wash potatoes right after digging. Brush off excess soil and let them cure in a dark, well-ventilated, cool place (about 60-65°F) for 10-14 days. This heals minor wounds and thickens the skin. After curing, store them in a completely dark, cool (40-50°F), humid place. Properly cured and stored potatoes can last for months.

Frequently Asked Questions (FAQ)

Can I grow potatoes in the Arizona summer?

It is not recommended. Potatoes are a cool-season crop and tubers stop forming when soil temperatures exceed about 80°F. Summer heat will stress the plants and lead to a very poor or non-existent harvest.

What if I miss the main planting window?

You can try planting in very large containers. This gives you more control over soil temperature. You can move the container to a slightly shaded area during a heatwave to extend your season a little bit.

How often should I water my potato plants?

Aim for deep, consistent watering. In the low desert, this might mean watering every 3-4 days, especially as plants get larger. Always check the soil moisture a few inches down; it should be moist, not soggy or bone dry.

Why are my potato leaves turning yellow?

If it’s near the end of your growing season, this is natural senescence. If it happens early, it could be overwatering, a nutrient deficiency, or the beginnings of a disease. Check your watering schedule and soil drainage first.

Can I save my own seed potatoes for next year?

It’s possible but not always advisable for beginners. You must select the healthiest plants, store the tubers perfectly, and they can still carry over soil-borne diseases. For most gardeners, buying new certified seed potatoes each year is the safest choice for a good crop.

Growing potatoes in Arizona is a rewarding challenge that hinges on timing. By planting in the correct window for your region and choosing fast-maturing varieties, you set yourself up for success. Pay attention to watering, keep the tubers covered with soil, and protect your plants from extreme heat. With this knowledge, you’re ready to enjoy the simple pleasure of digging up your own homegrown potatoes, even under the Arizona sun.