Don't confuse sweet
potatoes with Irish potatoes
Bill Sevier: Ask a Master Gardener
Saturday, March 25, 2017
Q: I would like to grow some sweet
potatoes, or yams. Are they grown the same way as Irish potatoes? John, Tulsa
There is so much confusion about these potatoes
and yams that it is worthwhile to try to sort it out.
The only thing Irish potatoes and sweet potatoes
have in common is that they are both grown underground and are great sources of
food worldwide. Both are nutritious.
Sweet potatoes, which are grown widely, are
tasty and have several vitamins, beta-carotene and abundant antioxidants. The
Irish potato, also nutritious, was the chief source of food in Ireland until
the mid-1800s when a potato disease (blight) devastated the crops. Almost 1
million Irish people starved and another million emigrated to Canada and the
U.S.
Sweet potatoes are a tropical warm-season plant
and botanically are true roots. They are planted in early June after the soil
warms as “slips” — which are small plants grown from the surface of a mature
sweet potato. These parent potatoes are either partially immersed in water or shallowly
planted in moist sandy beds where the small plants, or slips, develop on the
potato. They are removed and planted individually. The process is a bit more
involved but can be done by anyone. Full instructions are outlined in OSU Fact
Sheet HLA-6022, available at tulsamastergardeners.org.
Irish potatoes, on the other hand, are
cool-season crops, which should be planted mid-February through mid-March.
These potatoes are not roots but underground stem-tubers. Like above-ground
stems, they have buds from which a new plant may grow. To grow this type of
potato, a whole potato is cut into generous sized sections, called seed pieces,
which contain two or more of these buds or “eyes.” After planting, new plants
grow from the eyes. It is best to use only potatoes sold for seed pieces; those
in the market may have been treated to prevent sprouting.
Both types of potatoes require a long growing
season, the sweet potato 3-4 months and the Irish potato about 2-3 months.
A misconception about sweet potatoes concerns
“yams.” Most of us have eaten, or at least heard of, candied yams, a
traditional Thanksgiving food for some. However, candied yams are not actually
yams. Yams are tropical root crops grown in South America and Africa. They are
not at all related botanically to the sweet potato. The term yam originated to
distinguish certain types of orange sweet potato and is a corruption of an
African word for the actual yam.
One question that Master Gardeners are often asked
is whether ornamental sweet potatoes such as the cultivar “Margarita” are
edible. The answer is that they are edible, but it is said that they do not
have a pleasant taste. However, interestingly, is that not only do they have an
attractive vine, for which they are grown, but also most have unique purple
potato skins.
Garden tips
All cool-season vegetables, strawberries,
asparagus and other small fruit may be planted this month.
Established broadleaf weeds can easily be
controlled in lawns at this time with postemergent broadleaf herbicides. These
herbicides are most effective in spring and fall when weeds are rapidly
growing.
Cut down dead pine trees as soon as possible.
Most of these trees died of pine wilt disease due to a nematode infection. The
infection is spread by the pine sawyer beetle, and dead pines are a source of
infection carried by these beetles.