Potatoes are a staple crop, but growing them often starts with the confusing term: “potato seeds.” For most home gardeners, “seed” refers not to a tiny botanical seed, but to a small, specially grown potato tuber used for planting. These tubers are the preferred starting material because they produce a genetically identical clone of the parent plant, ensuring predictable results and a reliable harvest. Understanding the difference between the common “seed potato” and the botanical “True Potato Seed” is the first step in successful potato cultivation.
Certified Seed Potatoes: The Standard Planting Material
The most reliable way to begin a potato crop is by planting specialized tubers known as certified seed potatoes. These are small, whole potatoes or pieces of a tuber that contain at least one “eye,” a bud capable of sprouting a new plant. Using tubers ensures the resulting plants are exact genetic copies of the parent, meaning the gardener knows exactly what variety and characteristics they are planting.
The “certified” designation is critical for disease control. Certification means the seed stock has been grown, inspected, and tested by an authorized state or provincial agency to meet specific health and purity standards. This inspection ensures the tubers are within tolerance for certain diseases, such as Potato Virus Y, and have zero tolerance for destructive pathogens like Bacterial Ring Rot. By purchasing certified stock, gardeners avoid introducing harmful, persistent diseases into the garden soil, which could compromise future crops for years.
Home gardeners typically find certified seed potatoes available for purchase starting in late winter and early spring. Online specialized seed catalogs are a primary source, offering the widest selection of varieties, including heirloom and niche types. Local garden centers and nurseries are reliable vendors for popular, regionally adapted varieties. For those needing larger quantities, agricultural supply stores often stock certified seed potatoes in bulk bags.
The certification process limits the number of generations a seed lot can be replanted to maintain health standards. This system ensures the seed stock remains vigorous and relatively free from the buildup of viruses that accumulate over successive clonal generations. Therefore, looking for the official certification tag on the bag is the most important step a home gardener can take before planting.
Understanding True Potato Seed (TPS)
True Potato Seed (TPS) is the actual botanical seed produced by the potato plant’s flower, forming inside a small, berry-like fruit. Unlike planting tubers, TPS is the result of sexual reproduction, meaning it is genetically diverse. Each seed produces a plant with unique characteristics, leading to an unpredictable mix of colors, shapes, and flavors in the resulting potatoes.
For the typical home gardener, starting potatoes from TPS is less common and more challenging than using tubers. The seeds must be started indoors six to eight weeks before the last frost, similar to starting tomatoes, and require careful management of light and temperature to germinate successfully. This process adds significant time and complexity to the growing season compared to simply planting a tuber directly into the garden soil.
TPS is primarily utilized by plant breeders and advanced growers who wish to develop new varieties or maintain genetic diversity in their stock. Because true seeds are not clones, they often carry a much lower risk of transmitting pathogens that are commonly passed down through infected tubers. Sources for TPS are generally limited to highly specialized seed companies or dedicated breeding programs that focus on this niche market.
The main benefit of TPS for the average gardener is the opportunity to experiment with entirely new potato genetics and explore unique traits not available in standard commercial varieties. However, the requirement for a long indoor head start and the uncertainty of the final tuber characteristics make TPS a secondary option to planting certified seed tubers.
Why Avoid Grocery Store Potatoes
Planting potatoes purchased from a grocery store carries significant risks and is strongly discouraged for two primary reasons. The first concern is the high potential for introducing harmful soil-borne diseases into the garden environment. These “ware potatoes,” intended for consumption, are not subjected to the rigorous inspection and certification programs designed to screen for viruses and bacteria.
A grocery store potato may be carrying viruses like Potato Virus Y or fungal diseases such as blight, which do not harm human health but can remain in the soil for years, subsequently infecting future potato crops. Once a garden bed is contaminated with these persistent pathogens, it may be unsuitable for growing potatoes or related nightshade family plants for an extended period. This disease risk alone makes the practice a false economy compared to purchasing certified stock.
The second major reason for avoidance is the common use of sprout inhibitors on commercial potatoes to extend their shelf life. Chemicals like chlorpropham (CIPC) are routinely applied to prevent the tubers from sprouting in storage and on store shelves. While this treatment keeps the potatoes looking fresh for consumers, it severely hinders or outright prevents them from successfully sprouting when planted.
Even if the potatoes eventually sprout, the chemical residue can negatively impact the plant’s growth and vigor. Although organic grocery store potatoes are less likely to be treated, they still pose the substantial risk of carrying uncertified plant diseases. Therefore, the low cost of a consumption-grade potato does not outweigh the potential long-term damage to the garden soil and the likelihood of a failed crop.