Can grocery store potatoes be planted directly?

Potatoes purchased at grocery stores deceptively invite hidden dangers to gardeners. I discovered this the hard way when a single unusable crop partially or fully blighted my garden soil. Grocery store potatoes often harbor fungal spores that you cannot see. Commercial anti-sprouting chemicals, like chlorpropham, can take the risk away by reducing sprouting but can take vigor away from the plants too. Certified seed potatoes eliminate all of these potential problems.

Chlorpropham persists in soil for up to 18 months. My soil test showed residual chlorpropham levels at least 3 months after treating the potatoes and composting the soil. Chlorpropham inhibits root hair formation. Certified seeds have not been treated with chlorpropham. Now, I use certified seed potatoes for Elba or Kennebec varieties I source from a registered supplier. The effort is worth it given their performance and overall cost, which is higher for the seed potatoes.

Soil preparation is the most important thing for organic growers. Solarize beds with clear plastic for 6 weeks. This is effective in killing blight spores at 125°F. I also rotate my potato plots every year. I've even got marigold borders around my plots to repel nematodes. I've drastically reduced my pesticide use by 90% in my garden in Maine by using the above methods.

Emergency measures are available in case you are using grocery potatoes. You can soak tubers in water heated to 120°F for 15 minutes to kill fungi on the surface. Use wood ash to cure cuts in the tuber before planting. Check for leaf spots daily. I specifically reserve this measure for rare heirloom varieties that cannot be obtained as certified seed.

Read the full article: When Plant Potatoes: Expert Timing Guide