Potatoes are a rewarding and popular garden crop for home growers across Missouri. Successful harvesting depends on accurate planting timing, which must align with the region’s unique spring weather patterns. The goal is to establish plants during a cool, moist period, allowing them to mature before the intense heat of mid-summer stresses the developing tubers. Understanding the local climate, rather than relying on a fixed calendar date, is the most important factor for a bountiful yield.
Determining the Ideal Planting Window in Missouri
The precise time for planting potatoes in Missouri is determined by consistent ground temperature, not a fixed calendar date. Potato seed pieces thrive best when planted into soil that has warmed to at least 45 degrees Fahrenheit, with 50 degrees Fahrenheit being the ideal target for rapid sprouting and growth. Planting in cooler soil can lead to the seed pieces rotting before they sprout.
Missouri’s diverse climate dictates a staggered planting schedule from south to north. Gardeners in the warmer southern regions can often begin planting as early as mid-March to early April. Conversely, those in the colder northern zones must typically wait until late March or even mid-April for the soil to reach the necessary temperature. Potatoes need to complete their primary tuber development before the heat of July and August sets in. Tuber formation slows significantly when soil temperatures rise above 75 degrees Fahrenheit, which can severely limit the final harvest size.
Essential Pre-Planting Preparation Steps
Proper preparation is necessary before planting to ensure healthy plant establishment. Use certified, disease-free seed potatoes purchased from a reputable supplier to avoid introducing common soil-borne pathogens. Larger tubers should be cut into blocky pieces, weighing approximately one and a half to two ounces, ensuring each piece contains at least one or two visible “eyes” or sprouts.
After cutting, the seed pieces must be cured for two to five days in a dry, airy location away from direct sunlight. This process allows the cut surface to form a tough, leathery callus. The callus acts as a protective barrier, preventing moisture loss and reducing the risk of fungal rot once planted. Select a location that receives full sun and has loose, well-draining soil, ideally with a slightly acidic pH range of 5.3 to 6.5, which helps deter potato scab disease.
Care and Maintenance After Planting
Once planted, continuous care focuses on encouraging tuber growth and protecting the developing potatoes from light exposure. The primary maintenance task is “hilling,” which involves mounding soil up around the base of the plant stems as they grow. This practice should begin when the plants reach a height of six to eight inches, covering all but the top few leaves.
Hilling serves two main purposes: it provides a deep, dark environment for new tubers to form along the buried stem, and it prevents sunlight from reaching exposed potatoes. Tubers exposed to light will turn green and produce a mildly toxic compound. Consistent moisture is also important throughout the growing season, particularly during the flowering stage when the plant is actively setting its tubers. Watering should be deep and regular; allowing the soil to dry out completely can cause misshapen or cracked potatoes.
Harvesting and Curing Potatoes
Potatoes can be harvested at two different stages depending on preference. “New potatoes” are small, thin-skinned, best for immediate consumption, and can be gently dug up approximately two weeks after the plant begins to flower. For mature, storage-ready potatoes, the harvest signal is when the plant’s foliage naturally yellows and completely dies back.
To ensure the skins are fully set and hardened for long-term storage, wait approximately two weeks after the tops have died before digging up the tubers. This delay allows the skins to toughen, minimizing bruising and rot during storage. After gently digging, mature potatoes must be cured by placing them in a dark, humid environment, ideally between 45 and 60 degrees Fahrenheit, for about ten days. This curing process heals any minor scrapes on the skin before moving them to a cool, dark storage location.