Growing sweet potatoes in a very marginal zone

General Gardening
#1

This is my second year trying to coax growth from sweet potatoes in the maritime PNW. With a lot of tweaking, I’m finally starting to get some productivity.

The first challenge was whether to order slips or grow my own. My experience with ordering slips (Sandhill Preservation, Johnny’s Selected Seeds) has been that the slips arrive late and suffer from transit. This year I decided to start my own from supermarket varieties. There are at least 3 unnamed varieties carried by my local supermarket. By researching the PLU database, I found the following: Beauregard #94816, Japanese #94817, and Garnet #94074.

I placed the potatoes lengthwise in a covered bin of damp peatmoss/perlite on top of a heating pad. Within 3 weeks the potatoes had started to sprout. I continued growing them under lights until the sprouts were 5-6" tall. Then I cut off the sprouts and placed them in water.
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After 1 week the sprouts had grown roots and I transplanted them to pots to wait for my soil to warm up to 65F. I grew 3 plants of 4 varieties under cover in two 4x4x2 black plastic totes with black weed cloth on top. I watered them about once every 2 weeks. Next year I will need to increase the watering.

The results probably looks pretty pitiful to those who have long hot summers! …i.e. a lot of long skinny tubers! Perhaps with more consistent water I can get some beefier ones. Of the 4 varieties planted, Beauregard produced tubers with the most mass. Will be trying Beauregard
again next year.
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Where can I buy sweet potatoes to make my own slips?
#2

Looks like success to me. Get 'em in the ground in May and harvest in Sept or before a freeze.
Even planted July 4th they bear some here in KY.

#3

I have been growing my own slips too.

#4

Nice harvest. I’m down in PDX and have experience growing them and get good harvest averaging 3lbs a plant). Few tips I can pass on:

  • Don’t plant them early, wait until the weather is hot. I have planted on 4th of July and got the better yields than those that were planted in mid may.

  • When you make your own slips select those that are 3-5mm thick has maximum 4 nodes inside the soil this will help getting bigger storage roots than the pencil roots.

  • Water the newly planted slips twice a day for a week or ten day so that they are moist this is the period when the decides how many storage roots to form.

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