Planting Out Sweet Potato Slips

Sweet Potatoes

Rest assured that in the days between their arrival and the day of planting, your sweet potatoes will have recuperated and will indeed look great!

- Read our prior post for simple instructions on holding slips under favorable conditions.

The basis for success with any field-grown crop is that it is well-matched to the soil type. For sweet potatoes, the ideal is a well-drained, sandy loam.

Not only that, but the soil needs to be warm as well. Here in Central Maine, we lay black plastic mulch (you can also use solar mulch) along the entire length of our bed — which also does a good job suppressing weeds. Underneath the mulch we run a line of drip tape, for irrigation later in the season.

Well-drained Soil

Ideal soil conditions for Sweet Potato planting

Mulch is used to suppress weeds

If you’re planning to put in a large crop of sweet potatoes, a transplanting tractor can save you considerable time. But ours was a relatively small planting this year, so we put ours in the ground by hand. Prior to planting, we rolled out a measuring tape and punctured holes in the plastic 12 inches apart, so each transplant would be equidistant from its neighbors.

We went with standard spacing this year, but there has been some research to evaluate the effects of different in-row spacing and other factors on sweet potato yield. 

If you are space-limited and concerned about yield, you may want to look into the results, or check with your local extension agency for recommendations tailored to your regional conditions.

Puncturing holes in the plastic

Ensuring transplants are equidistant from they're neighbors

With all of the holes marked and the field stakes placed, it’s time to begin planting. If you’ve potted up your slips to hold them over for a while, remove them from their container like you would any transplant. Then, gently pull apart the slips to separate them. Even during a relatively short holding period, they will begin to develop a more robust root system.

Remove slips from containers carefully

A robust root system developing

The next step is to create a hole deep enough to accommodate each slip, as they can vary in length. To ensure consistent yield, make sure that at least two of the nodes at the base of the slip are below the soil line.

A closer look at the nodes

If the slips have a lot of fibrous roots, you will also want to bury these all below the soil line. There are various ways to accomplish this, but we find it easiest to use a dibble. Gauge each slip’s length and fibrous roots, then drive the dibble down into the soil and rotate it to widen the hole — and you have a perfectly sized hole, as simple as that. Place one slip per hole. If you do find that some of the slips are too long and you can’t dibble a deep enough hole, you can trim a bit of excess from the bottom.

Placing one slip per hole

Demonstrating planting

Drive the dibble down into the soil

A look at the plants

With the slip in the hole, push the surrounding soil back in. Firm it with a thorough watering, which will also provide the plants with needed moisture. 

Push the surrounding soil back in

Again, the plants may look a little droopy or wilted from the process. Transplanting can cause shock to all plants, especially if it is a sunny and hot day, as it was when we were planting our slips. Just keep the bed watered and give your plants a few days to establish themselves.

Often times the existing foliage on the slips will wither and die back, but new foliage will emerge. It can take up to one month before the plants really get growing here in Maine, especially if the weather is cool and cloudy.

Plants may look a bit droopy

Transplanting may shock the plants

Due to the unpredictable nature of northern spring weather, we added row cover to our planting. Row cover is very helpful to growers at higher latitudes, as it keeps the plants warmer while becoming established, and it discourages deer from browsing if you don’t have a fence (they love sweet potato vines).

Frequent windy weather that causes the billowing fabric to jostle the slips prompted us to use hoops under Agribon-19, but we have used it successfully without hoops in the past. The cover stays on until the plants are established, around July 4th, and then we will put in back on to extend the growing window at the end of summer.

Check back later this summer to see how the sweet potato vines have taken off!