Friday, June 26, 2015

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
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

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

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!

Monday, June 22, 2015

Arrival & Preplanting Care of Sweet Potato Slips

The Slips Arrive 

Packages containing sweet potato slips were shipping at a steady rate earlier this month. When live plants are delivered, it’s always best to plant them immediately — but when life and changes in the weather intervene, that isn’t always possible. Here’s how to keep your slips healthy until you can put them in the ground.

Open the box as soon as it arrives. The rigors of shipping can leave them looking the worse for wear, with pale, wilted, or even dead leaves. But this is not ordinarily cause for alarm— sweet potato slips are stronger than they appear. There may be variation in the size of the slips and the extent of the finer, fibrous white roots growing off of them. Some slips won’t have fibrous roots, some will have many, but they will all grow if planted in the proper environment.


Holding Your Slips for a Couple of Days 

If it’s just a day or two before you’ll be planting, simply moisten a paper towel and loosely wrap it around the root ends of the slips (if the slips do not have any fibrous roots, just wrap up the cut end). Sweet potatoes are of tropical origin and do not fare well in temperatures below 60°F/16°C, so keep them at room temperature. Protect them from direct sunlight, and prop them upright — often we will stick each bundle of slips in a glass or jar if we expect to be planting them within a day or so.

Holding Sweet Potato Slips for More than a Day or Two 

We were unable to plant our trial immediately due to cool wet weather, so our slips received long-term care to keep them happy until conditions improved. If you need to hold your slips for more than a couple days, here’s what to do.

After opening the box, gently and loosely separate the roots from one another, discarding any peat moss from the roots’ storage that was shipped with the plants.


Fill a container half full with potting mix. Arrange the slips loosely in a circle around the edges of the container, then fill the rest of the container with more potting mix. If the slips have fibrous roots, try to cover them with the potting mix. Water around the slips to help settle the potting medium, and add more medium if needed. Store at room temperature, out of direct sunlight (we put them under an occupied greenhouse bench).


If you have received more than one sweet potato variety, as we had, be sure to plant the slips in separate containers and label accordingly. Keep the containers moist. In just a day or two, they will be flourishing with bright, healthy leaves.

View Our Sweet Potato Varieties »

Tuesday, June 16, 2015

Update on our Asparagus Crown Planting: Part III

Our Final Asparagus Crown Planting Update 

May 2015

Here’s the last update ‘til fall for our newly planted asparagus crown bed. At the end of the last post, we mentioned that as the spears grow, you will gradually fill in your furrow with soil until its top surface is even with the surrounding soil line. We have been doing this since our last post, adding the final layer of soil to finish filling in the furrow today.

Surrounding Soil
Filling the Furrow
The process is the same as before: Gently pull soil into the furrow, while not completely covering any buds that are still emerging. Yesterday a large afternoon thunderstorm had already started to fill the furrow with surrounding soil. We used a collinear hoe to once more level out the rest of it. You might notice in the photos that some of the crowns are establishing faster than others and those spears have already grown well above the soil line. This is okay – some are just slower to snap out of their stay in cold storage than others and will catch up eventually.

Leveling Out the Furrow
Now that the soil level is where it should be, the next step is to cover the bed with mulch to suppress any weeds that might begin to grow. Keeping your asparagus bed free of weeds will not only save you a lot of labor, but support nutrient and moisture availability to the crowns. We use straw to mulch our bed, but other materials that allow water to percolate through, such as composted leaves, can also be used. Leave a couple inches of soil surface open around the line of spears down the center, of the bed, or keep the mulch layer thin in this area, especially if there are any crowns with spears that have not yet emerged above the soil line.

See photos below:

Your asparagus bed is now well set until fall — but keep an eye on it, and keep the soil moderately moist throughout the hot summer months.

In the fall, when the fronds have died back, cut them off at soil level, and be sure to remove all the debris, to eliminate potential habitat for asparagus beetles. Fall is also the time to add more compost, if needed, and to freshen up the mulch for the winter ahead.