St. Patrick’s Day is traditionally a reminder that it is time to plant potatoes (although anytime between March 15th and April 15th is fine in Western North Carolina). Another link between potatoes and the Irish, however, is the Irish Potato Famine of the 1840s—the late blight that caused that catastrophe is an important reason to think carefully about potato plantings. What are the pros and cons of growing your own?
What potatoes want
Potatoes will grow well in the ground—and even in containers—in WNC if you give them:
• Fast-draining soil
• Full sun
• Slightly acid conditions (pH from 5.5 to 6.5)
• Keep them well-fertilized—don’t overdo nitrogen fertilizers or you’ll get more green foliage than tubers—10-10-10 or 10-20-20 are usually fine!
• Weed regularly.
Potatoes have a relatively long growing season—at least 70 days, and as long as 150 days from planting—and plants likely potential yield can be as low as less than one pound per plant! Even high yielding varieties produce only 3 to 4 pounds per plant, so consider how much time and space you are willing to devote to a crop that is readily available at local markets.
In NC, varieties recommended for home gardens include ‘Kennebec’ (high yield, main season), ‘Red Pontiac’ (high yield, late season), and ‘Yukon Gold’ (medium yield, early main season)—all of which store well.
How to plant
Purchase seed potatoes, rather than potato seed—which will take much longer to produce potato tubers. Only certified seed potatoes are guaranteed to be free of disease, so do not risk introducing disease into your garden by using potatoes you purchase for eating! Seed potatoes may be whole potatoes or potato pieces that have “eyes”—indentations from which the plant foliage will grow. Your seed potatoes should NOT be shriveled or have sprouts before planting.
• Cut seed potatoes into pieces that weigh about 2 ounces—ideally with two or more eyes.
• Plant these pieces about 3 to 4 inches deep and about 12 inches apart.
• If you choose container planting:
o Use at least a five-gallon container with drainage holes.
o Plant 3 to 4 inches deep, but start with soil only 8 inches deep
o For larger, wider containers—such as bushel baskets—plant more than one piece about 8 inches apart from each other.
• Hill up earth around garden plants and add soil depth to container plantings once the stems grow 4 to 6 inches tall. Continue to hill up/add depth as the plants grow.
Insect pests—aphids, Colorado potato beetles, and flea beetles—may damage your plants’ foliage and affect your harvest. Seek out and destroy Colorado potato beetle eggs and larvae to avoid total defoliation!
Diseases are a much greater risk for your crop—and the long-term health of your garden. Potatoes may suffer from fungal, bacterial, viral, and nematode-introduced diseases. Although planting certified seed potatoes and rotating the place you plant potatoes each year may help avoid most diseases, late blight (Phytophthora infestans) is a disease that is devastating to potatoes, and may impact tomatoes, too!
Potatoes late blight lifecycle
Late blight can survive year-round only on plant material, so late blight typically only begins affecting plants in our area once it moves north from frost-free areas in the south. Unfortunately, if you leave infected potato tubers in the ground, late blight may overwinter here and then infect your tomatoes earlier in their growing season. Although it may seem easy to remove all tubers from the ground, anyone who has grown potatoes will know that it is very easy to miss tiny tubers that will sprout again the next spring.
Bottom line: to avoid the risk of introducing late blight into your garden, think carefully about planting potatoes!
Article by Debbie Green, Buncombe County Extension Master Gardener Volunteer
For more information:
De Jong, H., J.B. Sieczka, and W. De Jong (2011). The Complete Book of Potatoes: What Every Grower and Gardener Needs to Know. Portland, OR: Timber Press.
Potato varieties grown in NC:https://ncpotatoes.org/varieties/
Potato late blight: https://content.ces.ncsu.edu/potato-late-blight
General advice about vegetable gardening: https://content.ces.ncsu.edu/extension-gardener-handbook/16-vegetable-gardening