Growing potatoes is rewarding, but the terminology for planting material often causes confusion. Potatoes are not typically grown from a small, dry seed packet. Most gardeners use specialized tubers, which are often mistakenly referred to as “potato seeds.” Understanding the difference between these vegetative pieces and the plant’s actual botanical seeds is the first step toward a successful planting season.
Understanding Potato Propagation Material
The two distinct materials used to start a potato crop are seed potatoes and true potato seeds (TPS). Seed potatoes are small, whole tubers or pieces of tubers that are clones of the parent plant. This vegetative propagation method is the standard practice in commercial and home gardening because it ensures the resulting crop is genetically identical to the parent.
TPS are the actual botanical seeds produced by the potato flower after pollination. Since TPS result from sexual reproduction, they produce genetically diverse offspring. This variability makes TPS generally preferred by plant breeders seeking new varieties, rather than gardeners focused on predictable, high-yield harvests.
Sourcing and Preparing Certified Seed Potatoes
Most gardeners should acquire high-quality seed potatoes from a reliable source, such as a specialized supplier, seed catalog, or local garden center. It is highly recommended to purchase certified seed potatoes. These have been inspected and tested to ensure they are free from common soil-borne diseases. This certification process helps prevent the introduction of devastating viruses, fungi, and bacterial pathogens into your garden soil.
Planting potatoes purchased at the grocery store poses a serious risk, as they are intended for consumption, not planting. These tubers may harbor latent diseases that can contaminate your garden for years, making future potato planting difficult. Furthermore, many commercially sold potatoes are treated with chemical sprout inhibitors, which can hinder or entirely prevent them from growing effectively once planted. Using certified stock minimizes these risks and provides an assurance of quality and varietal purity.
Pre-Sprouting (Chitting)
Once the seed potatoes are acquired, they benefit from a pre-sprouting process called “chitting” to give them a head start before planting. Roughly four to six weeks before your intended planting date, place the tubers in a single layer in trays or egg cartons with the “rose end,” the end with the most eyes, facing upward. They should be kept in a bright, cool, and frost-free location, ideally around 50°F (10°C).
The exposure to light and cool temperatures encourages the development of short, sturdy sprouts. If the sprouts grow long, thin, and white, the location is too warm or dark. This process shortens the time from planting to harvest by ensuring the plant begins active growth immediately upon entering the soil.
Cutting and Curing
If the seed potatoes are larger than a chicken egg, they can be cut to yield more planting pieces. Use a clean, sharp knife to cut the tuber into blocky pieces, with each piece weighing at least 1.5 to 2 ounces. Each cut section must contain a minimum of one or two healthy eyes from which new growth can emerge.
After cutting, the pieces should be allowed to “cure” for one to three days in a dry, airy place away from direct sunlight. This curing period allows the cut surfaces to form a tough, protective callous or scab. The cured surface acts as a natural barrier, significantly reducing the chance of the pieces rotting in cool, damp soil after they are planted.
Obtaining and Utilizing True Potato Seeds
True Potato Seeds (TPS) are a specialized option, representing the botanical seed of the potato plant. These seeds develop inside small, round, green fruits, called potato berries, which look similar to tiny tomatoes and form after the potato flower is pollinated. While it is possible to harvest these berries from a garden plant, most modern potato varieties do not flower reliably or produce viable seed.
Gardeners interested in this method usually acquire TPS from specialized breeders who have developed hybrid varieties for specific traits, such as improved disease resistance or unique colors. Since TPS are the product of cross-pollination, each seed carries a unique genetic blueprint, leading to a diverse range of tuber characteristics, even within the same planting. This variability is why the TPS method is often used in breeding programs to create entirely new cultivars.
Handling True Potato Seeds is similar to starting tomatoes or peppers from seed. They must be started indoors approximately six to eight weeks before the last expected frost date, planted in small containers with sterile seed-starting mix. The tiny seedlings are then transplanted into the garden once the weather is consistently warm. This process is more labor-intensive and requires a longer growing season than planting tubers. The resulting plants, in the first season, produce small tubers known as “seedling tubers,” which are then harvested and replanted the following year to produce a full-sized crop.