I have three types of sweet potatoes. The first contender is Beauregard. It is a typical sweet potato you find in American markets. I should have dug up three plants. I found one. The other two had died. The problem was this spring. I planted one week earlier than before and we got a cold snap (usually I plant on June 1st). It got down into the 30Fs. There wasn't a frost, but the Beauregard potatoes did not like it. I think it made them too weak to compete with their neighbors. The one plant that did survive produced very small tubers for a total of 8.9 oz. Pretty pitiful for the space of three plants.
Garnet had five plants and they mostly produced. I have a range of decent, but not big tubers and tiny little ones. The tiny ones were made by vines that had rooted as they grew, so not the original plant. Typically in our climate these won't produce anything at all. Extension services in New England usually tell us to put down black plastic and plant them a foot apart. In the south you can plant them three feet apart and they will spread into the whole area. The vines will root and produce decent tubers from that. This year I placed them a bit farther apart than normal to see how they would grow. Well Garnet obviously used the extra space to root. They produced a total of 9.14lbs. For 1.8lbs per plant which is decent but not stellar.
Next on the contender list is Purple. I got these a few years ago from Norma and have kept growing them every year as they do so well here. In other years they have made long snaky tubers that are a little hard to use, but this year they made huge monstrous tubers.
I had 21 plants total in the bed if they were all this productive I would have a harvest of almost 70 pounds in a 32sqft area. Of course I don't want to plant all Purple sweet potatoes. I like about half purple and half orange.
In the past I've had extensive insect damage that makes the skins inedible. I had to peel to eat them. The flesh was fine, but it meant I couldn't just roast a sweet potato to eat it. The Beauregard are the worst affected with the Garnet being the least. This year there is very little damage. A couple will have to be peeled, but most can be eaten anyway I like them. Whoohoo! I wish I knew why it was so much better this year. I haven't a clue what eats them. Maybe the sow bugs? But I'm sure I'll have bad years again. I was thinking of dumping Beauregard anyway and now that I've found it can't handle cold snaps in the spring, it has sealed its fate. I'll probably split the bed between Garnet and Purple from now on. Though if I can get my hand on some Covington slips I would love to try that one as they are supposed to grow well here.
The total harvest from this half of the bed was 19lbs 7.2oz. Since half the bed is about 16sqft this was a pretty good harvest even with Beauregard not pulling its weight. Last year I grew them in the wooden raised beds. This year they are in the brick raised beds which are warmer. Last year half a bed produced 15 pounds, so I'm happy with the added production and will keep them rotating every other year in the two brick beds. I can't wait to see what the rest of the harvests brings. It might be more. It might be less.
The reason for the greenhouse is that sweet potatoes are supposed to be cured at 80F-85F and 90%-95% humidity for 4-7 days. I don't have those conditions. So I do it in a plastic box in the sun. I don't close the lid all the way though as that would get mold to form. And I'll cure them for a longer period than a week as they only get warm enough for a short time during the day. It isn't perfect, but it works. My sweet potatoes always last until basement starts warming up in the summer. If I have any leftover then I cook them up and freeze them.
Now the long wait before eating them begins. I hate waiting. But they won't develop their sugars until after they are cured and stored for a few weeks. I might break into them earlier as they are still good starchy and not sweet, but not quite as good.