garden q&a: too much moisture ruins crop
Q: My question is about my sweet potatoes. They were very deformed with big ridges and grooves in them again this year. I would like to know what is causing this. They taste OK but look awful and don't keep well. Even some of the smaller ones were like that.
Someone told me it was because they were done growing in dry weather and then rain came and they started growing again, but I am not sure that is the problem. Thanks for your help in advance.
A: Too much water at the end of the growing season is indeed the reason your sweet potatoes are cracking. When the vines begin to die back at the end of the season, gardeners are often tempted to irrigate, thinking it will somehow prolong the life of the vines and lead to the production of larger tubers. But, instead, this practice causes the interior of the tubers to swell and crack open the skin.
Irrigation should stop three to four weeks before harvest. Though you can't control the weather, you can control excess irrigation. Splitting also sometimes happens in poorly drained soils.
For your best chance of a successful sweet potato crop, begin by choosing short-season varieties. Purchase only certified-disease resistant slips (starter plants) from a reputable source, and locate the plants in the hottest part of the garden. Plant the slips three weeks after the danger of frost has passed, and space them 12 to 18 inches apart.
To warm the soil, build an 8-inch-high ridge to plant them in, or cover the soil with black plastic for a few weeks before planting. The tubers are ready to harvest a few weeks after the vines have died back. They are a long-season crop — taking 100 plus days from planting until harvest.
Sweet potatoes prefer hot, dry conditions, which do not consistently occur here in Western Pennsylvania, making a good sweet potato harvest a hit-or-miss proposition. Still, homegrown sweet potatoes are amazing and well worth the effort.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.
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