Corn cultivation in Arizona requires growers to navigate the state’s extreme climatic variations for a successful harvest. Planting time depends entirely on localized conditions, primarily elevation, which creates two vastly different growing environments. Successful planting demands careful planning to synchronize the corn’s heat-loving growth cycle with brief temperate windows, all while mitigating the intense heat and severe lack of natural moisture common to the region. Arizona does not offer a single, continuous growing season.
Planting Schedule for Low Desert Regions
The low desert regions, including Phoenix and Tucson, operate on a dual-season planting schedule due to intense summer heat. The first planting opportunity runs from late February through March, allowing the corn to mature before high summer temperatures arrive. The goal is to harvest the crop by early June, before temperatures consistently reach triple digits.
Once daily temperatures exceed 100°F, corn pollination is severely hindered, resulting in scattered kernels. Planting must be avoided during the extreme heat period, which lasts from late May until mid-July. The second planting opportunity aligns with the North American Monsoon, starting in mid-July and extending into early August. This late-summer planting benefits from increased humidity and slightly lower temperatures, supporting a fall harvest in September and October.
Planting Schedule for High Elevation Regions
Regions above 5,000 feet, such as Flagstaff, Payson, and Prescott, experience a single, short growing season. The primary constraint is the danger of frost extending late into the spring. Planting must be delayed until the threat of the last spring frost has passed, often not until late May or early June in the highest elevations.
In the Flagstaff area, the average date for the last spring frost is around June 10, creating a short window for warm-season crops. Planting must be concluded by mid-July at the latest. This strict deadline ensures the corn has sufficient time to reach maturity before the average first fall frost arrives in late September. The growing season can be as short as 100 to 120 days, necessitating the use of quickly maturing corn varieties.
Essential Soil and Temperature Conditions
Regardless of elevation, the minimum soil temperature for planting corn is 60°F, with 65°F being optimal for germination. Planting seeds into cooler soil increases the risk of seed rot and encourages slow, weak emergence. Growers should use a soil thermometer placed a few inches deep to confirm this temperature, ignoring air temperature readings.
Corn thrives in rich, fertile soil, but Arizona’s native soil presents challenges, often characterized by high alkalinity (pH 7.0 to 8.5). This high pH can “lock up” essential micronutrients like iron and zinc, making them unavailable to the corn plants. The soil is also frequently rocky or sandy, resulting in poor water retention and low organic matter.
To counteract these issues, incorporate generous amounts of well-aged compost or manure before planting. This provides a nitrogen boost, which corn demands, and improves the soil’s structure and water-holding capacity. In cases of high alkalinity, adding elemental sulfur can help lower the pH over time, improving the availability of nutrients.
Managing Water and Choosing Corn Varieties
Effective water management is essential for growing corn in Arizona’s arid climate, as the plant requires deep, consistent moisture. The most efficient method is drip irrigation, which applies water directly to the root zone, reducing loss from evaporation. Consistency is crucial during the reproductive stages, silking and tasseling, when water stress can cause poor pollination and reduce ear development.
Growers must select corn varieties adapted to the region’s short growing windows. Short-season varieties, maturing between 60 and 90 days, are ideal, especially for the brief summer window in high-elevation areas. Pima 60-day Corn is a fast-growing variety that thrives in the heat and humidity of the monsoon season.
Hopi Blue Corn has been successfully cultivated in the desert for centuries due to its deep-rooting characteristics. When selecting sweet corn, standard sugary (su) types generally have better germination rates in the cooler soil temperatures of the early spring planting. Choosing the right variety and implementing precision watering are primary factors that determine success.