I’m in Vermont zone 4b and trying them this year using the same method for slips and putting them in grow bags. I have a 16’x8’ cattle panel greenhouse that is warmer and my experiment is growing outside and inside. I do get a longer season in my greenhouse.first year for me trying 😊
Here in the Willamette Valley in Oregon, we had very similar results in our bed last year, but a much smaller scale (maybe 120 sq ft?). I think it has to do with our low temps being at or below 50° for most of the growing season. We get nice and warm for a couple months, but rarely above 95 here, so our average temperature just doesn't cut it on its own for sweet potatoes. I planted probably 20 slips around our main garden area, and got maybe 35 lbs in the end. Most were thin fingers, but we had the best results in one hot spot. I put two slips against the south face of our house where a 55gal black water barrel sits, where our in ground citrus trees are. We got the biggest tubers there, and probably about 3 lbs worth per slip. So I'm trying a couple tweaks this year to eke out higher soil temps. First, I bought some 15gal fabric grow bags, pretty much for this, because they should soak up a lot of heat. I'm planting a few slips per pot, maybe with a single tomato or pepper plant in the middle to tie up some of the excess nutrients (too much causes lots of vining but few tubers) and get a bonus crop from the pot. Next, I'm going to put clear plastic strips over the planting rows in the garden, cutting slits every 12-18" or so for planting. I may even use a pvc low tunnel frame I have there for my winter garden to hang some fabric row covers to hold in a little more heat close to the ground. The goal is to get the soil well above 65° quickly so these things will take off and bulk up. I've also heard that they only need about 3' of vine, so I'm also going to try trimming vines back to about that length when they get unruly, and eat the leaves (they're delicious, and cook up like spinach!)
You are trying great things! We plan to grow sweet potatoes in 55 gallon drums cut in half this year. We also plan to keep them in the greenhouse to try to get them to last a little longer at the end of the season. We are trying 2 or 3 kinds this year, but they haven’t arrived yet! So I’m already feeling behind. Which varieties are you growing?
We had a few Okinawan that we resisted eating this winter, white outside and purple inside. They've been churning out slips for a while, and now a Garnet is finally putting some out. I had also planted some purple hawaiian (purple skin, purple flesh) last year, but I put them in really late and really small slips so I didn't get many from them. So I overwintered several vines at my office. I just cut the ends off of vines as I was harvesting, pulled off all but a few leaves and buried the stems a few per 8" pot, and some individually in little 4" pots (those aren't looking very happy about their home right now, so bigger is much better) Did the same for the Okinawan. They have kept on kicking in our windows here, and I've even been able to multiply the plants a couple times as they've slowly grown indoors. I think I have 20 or so vines sitting here at the office eager to hit the ground running, and about the same amount of slips at home living their best life in solo cups for probably another week or two. Boy, they sure took up a lot of space on our little garage bench!
