My post from two years ago on How to Grow Yams has continued to raise questions. Today I’ll share a few, along with my answers.

Cold Hardiness in Varieties of Yams

DEAN AKA LOWERALABAMA:

“David: I live in coastal Mobile, AL, zone 8b and I planted “purple yam” last year that I purchased at a local oriental food market. The vines came up and looked gorgeous until the frost nipped them back in December. We did have a rather cold winter this year with a few nights dipping down into the high teens. Anyway, I have been excited about seeing my vines come back up but as of yet I have not seen any live action. I figured it would be about time for the vines to appear since the Eddoes are sprouting up all along the fence lines where I also planted the “purple yam”. Well needless to say curiosity got the best of me: I pulled on one of the dormant vines and it easily snapped off at the ground. I got my small spade out and dug the “purple yam” up for inspection just to see that it looked like it was literally rotting/getting soggy. What is your take on this? I am considering buying some more “purple yam” off of Ebay and trying it again but it is expensive on Ebay. The oriental market is not carrying these right now. I am really looking forward to your insight on this one. Thanks in advance for your time and consideration.”

DAVID THE GOOD:

“Sounds like the cold got to it. I’m sorry it rotted out – the cold was probably too much for it. They’re really tropical. Try mulching heavily when you try again. Also, if it’s really wet, the roots will rot even in the tropics. A combination of cold and rain likely did it in.”

DEAN AKA LOWERALABAMA:

“Hey David another quick question. While looking at Ebay for Dioscorea Alata I ran across Dioscorea Trifida, the cush-cush yam. I am looking on the web and cannot find much information much less which USDA zone these will live in. Do you happen to recognize this yam and can you tell me if it will grow and survive in USDA zone 8b? Thanks again.”

DAVID THE GOOD:

“Yes – I’ve grown it before. 8b is pretty cold, but it may overwinter with heavy mulch.”

AKIRA:

“Hi David, I live in zone 4b of the US and was wondering if it would be possible to grow Chinese yam. I bought a small chunk from the Asian market and it ended up sprouting up a super long purple vine. Would it be able to grow properly in the zone I live in?”

DAVID THE GOOD:

“Probably not easily, but you might be able to keep it alive by planting right up against the south-facing wall of your house and mulching it over the winter.”

Note: Chinese Yam is BY FAR the most cold-hardy of all yam species. If you’re in zone 8 north, that’s the one to try.

Are Air Potatoes Edible?

KATHLEEN RODGERS:

“So you are saying that the air potatoes , the little things that look like miniature irish potatoes are not edible ?”

DAVID THE GOOD:

“It’s not quite that simple. The wild Dioscorea bulbifera bulbils in Florida are considered poisonous. That’s the most common “air potato.” They have a cousin that grows in the same region, Dioscorea alata, which has edible bulbils, though they’re usually too small to bother with. The roots on those are much better. D. bulbifera, though, unless it’s a cultivated variety known to be non-poisonous, is not safe to harvest and eat.”

DEAN:

“Good Morning David: Please clear something up for me. You are saying that the Bulbifera variety has both edible and non-edible varieties? If I am not mistaken your friend, Grower Jim, sells a Bulbifera variety that looks like a space rock that is supposedly edible. I purchased 1 of these last year but it never sprouted. Would like to hear your 2 cents on this. Thanks.”

DAVID THE GOOD:

“Yes, that is correct. There are edible varieties of D. bulbifera in cultivation, of which Grower Jim has some, and so do I. They are different from the wild forms growing around Florida. Those are bitter and poisonous.”

Air Potatoes which are likely to be poisonous:

There are other images on the UF Center for Aquatic and Invasive Plants page.

These are edible varieties:

Weird crinkly edges, faceting, etc., are common to edible types. Nice, round potatoes are generally poisonous.