Figuring out when to plant corn in Arizona is the first step to a successful harvest. Our unique climate means timing is everything, and getting it right makes all the difference.
Corn loves warmth but struggles in extreme heat. In Arizona, you need to work with our two main growing seasons. Planting at the optimal time ensures your corn gets the right conditions to grow tall and produce sweet, full ears.
This guide will walk you through the best dates, varieties, and tips for Arizona gardeners.
When To Plant Corn In Arizona
The short answer is you have two primary windows: late winter for a spring crop and late summer for a fall crop. The exact dates shift depending on whether you’re in the low desert or the high country.
For a spring planting, aim to get seeds in the ground from about mid-February through mid-March. This allows the corn to mature before the punishing summer heat arrives.
For a fall planting, wait for the peak heat to pass. The ideal window is from late July through early September. This gives the crop time to pollinate and develop during the milder autumn weather.
Understanding Arizona’s Climate Zones
Arizona isn’t just one climate. Where you live drastically changes your schedule.
- Low Desert (Phoenix, Tucson, Yuma): This region has very hot summers and mild winters. Frost is rare but possible. The two-season planting model works perfectly here.
- High Desert & Mountain Regions (Prescott, Flagstaff, Payson): These areas have a shorter, cooler growing season with a significant risk of frost. Here, you typically only have one planting window: after the last spring frost, usually from late April to early June.
Always check your local last frost date if you live in a higher elevation area. A surprise frost can wipe out young corn seedlings.
Why Timing is Critical for Corn Pollination
Corn is wind-pollinated. The tassels (at the top) release pollen that must fall onto the silks of the ears below. Arizona’s extreme summer heat is the biggest enemy of this process.
When temperatures consistently stay above 95°F, especially with low humidity, the pollen can become sterile or dry out. Silks can also dry up and become unreceptive. This leads to poorly filled ears with missing kernels.
By planting in the recommended windows, you ensure the crucial pollination phase happens when temperatures are more favorable, typically in the spring or fall.
Choosing the Right Corn Variety for Arizona
Not all corn is created equal for our climate. Look for varieties with two key traits: heat tolerance and a shorter “days to maturity” number.
- Early-Maturing Varieties (60-75 days): These are your best bet. They produce a crop faster, helping you beat the heat. Examples include ‘Golden Bantam’, ‘Early Sunglow’, and ‘Sugar Buns’.
- Heat-Tolerant Varieties: Some are bred specifically for warmer climates. Look for varieties like ‘Kandy Korn’, ‘Peaches and Cream’, or ‘Silver Queen’ which can handle stress a bit better.
- Super-Sweet vs. Standard Sweet Corn: Super-sweet types (SH2) are sweeter but often have less vigorous seedlings. In spring’s cooler soil, standard sweet corn (SU) or sugar-enhanced (SE) types might germinate more reliably.
Step-by-Step Planting Guide
Follow these steps for the best results.
1. Soil Preparation
Corn is a heavy feeder. It needs rich, well-draining soil. A few weeks before planting, work in 3-4 inches of compost or well-rotted manure into your bed.
You can also add a balanced, slow-release organic fertilizer. Corn prefers a soil pH between 6.0 and 6.8.
2. Planting Method
Corn is best grown in blocks, not single rows. This improves wind pollination.
- Plant seeds 1 inch deep in moist soil.
- Space seeds about 8-12 inches apart within the block.
- Space your rows about 24-36 inches apart.
- Water deeply immediately after planting.
A good tip is to plant a little extra seed and thin to the strongest seedlings later. This ensures you have a full block.
3. Watering Schedule
Consistent moisture is non-negotiable, especially during germination and when the stalks begin to tassel and silk.
- Water deeply, providing 1-2 inches per week.
- Use drip irrigation or soaker hoses to keep water off the leaves and conserve moisture.
- Mulch heavily around the plants with straw or wood chips to keep soil cool and retain water.
During peak summer heat, even fall crops may need supplemental watering to prevent stress. Check the soil frequently.
4. Fertilizing Your Crop
Corn needs a boost partway through its growth. When the plants are about knee-high (12 inches tall), side-dress them with a high-nitrogen fertilizer.
Simply scratch the fertilizer into the soil a few inches away from the stalks and water it in well. This feeds the plant just before its big growth spurt.
Common Pests and Problems in Arizona
Every garden has its challenges. Here’s what to watch for.
- Corn Earworms: This is the most common pest. The moth lays eggs on the silks, and the worm eats its way down the ear. To prevent, apply a few drops of mineral or vegetable oil to the tip of each ear’s silk just as it starts to brown.
- Aphids: They cluster on leaves and stalks. A strong blast of water from the hose can dislodge them. Ladybugs are a natural predator.
- Birds & Rodents: They may eat seeds or young shoots. Use lightweight row covers until plants are established.
- Wind Damage: Arizona monsoons can flatten corn. Planting in a sheltered spot or in a dense block helps plants support each other.
Harvesting Your Arizona-Grown Corn
Your corn is ready about 18-24 days after the silks first appear. The silks will be brown and dry, and the ears will feel plump.
Peel back a small part of the husk and poke a kernel with your fingernail. If a milky liquid squirts out, it’s perfect. If it’s clear, it’s not ready. If it’s doughy, it’s past prime.
For the best flavor, harvest in the early morning and get the ears into a pot of water or the refrigerator immediately. The sugars in corn begin converting to starch as soon as its picked.
FAQ: Planting Corn in Arizona
Can I plant corn in the summer in Phoenix?
It’s not recommended. The extreme heat in June and July will likely cause pollination failure, leading to no kernels on the cobs. Wait for the late summer/fall window.
What if I missed the spring planting window?
Wait for the fall planting window. Trying to plant in late spring for a summer harvest almost always leads to disappointment due to the heat.
How long does corn take to grow in Arizona?
From seed to harvest, most sweet corn varieties take 60-90 days. Always check the “days to maturity” on your seed packet and count from your planting date.
Can I grow corn in containers?
Yes, but choose a dwarf or short variety. Use a very large container (at least 18 inches deep and wide) and plant in a block of multiple plants for pollination. Watering needs will be more frequent.
Is it better to start corn seeds indoors?
Corn transplants poorly because it has a sensitive root system. It’s almost always better to sow seeds directly into your garden soil where they will grow.
By following this timing and these tips, you can enjoy the incredible taste of homegrown sweet corn right from your Arizona backyard. The key is respecting the climate and working with, not against, our unique seasons.