How to plant sweet potato slips in your vegetable garden

Knowing when and how to plant sweet potato slips in your garden is the first step to success with this crop. You can start your own slips or buy some already rooted from a local garden center or online supplier. However because they can be difficult to source, learning to grow your own slips is a useful skill. In this article I’ll guide you through the process of making your own sweet potato slips and show you when and how to plant them outdoors to get a strong start to the growing season.

Why you should grow sweet potatoes in your garden

I love growing – and eating – sweet potatoes. This member of the morning glory family is a fairly hands-off crop and produces long vines with attractive heart-shaped leaves. The plants offer a dual harvest of tender young leaves and shoots along with the sweet roots. Growing sweet potatoes in your garden or in large pots isn’t difficult but it does require a long growing season. You’ll need months of warm weather because most varieties need at between 90 and 120 days to go from planting to harvest.

And speaking of variety, you’ll find there are hundreds of sweet potato options with varied flesh colors including orange, white, and yellow. Picking a variety that grows well in your region is a key to success and popular sweet potato varieties include Beauregard, Georgia Jet, Vardaman, and Superior.

What are sweet potato slips?

The first step in learning how to plant sweet potato slips is to understand the planting process. Sweet potatoes aren’t grown from seed potatoes planted in the ground, but rather from slips. Slips are sprouts that emerge from the buds of last year’s sweet potatoes and are removed when they’re 6 to 10 inches in length. These rooted cuttings are then planted in garden beds or containers. 

How to make sweet potato slips: 2 easy methods

You may be able to find sweet potato slips locally at a garden center in spring or you can order them from a mail order company. But you can also make your own slips from a sweet potato. If you still have a sweet potato from last year’s harvest you can use that or my trick is to pick up a couple of locally and organically grown tubers from a farmers market. 

Each sweet potato produces a dozen or more slips and it takes about 6 to 8 weeks for the slips to grow to a harvestable size. Therefore aim to start this process 6 to 8 weeks before you need to plant the slips in your garden. Here are two ways to make sweet potato slips:

Method 1 – Planting in potting mix

• Fill a seeding tray or container with several inches of damp potting mix.
• Cut the sweet potato in half, lengthwise.
• Nestle each half into the potting mix and cover with another inch of growing medium. 
• Cover with a plastic dome or piece of plastic wrap and place in a sunny window or under a grow light.
• If you have a seedling heat mat, use it to speed up the process. 
• The sprouts will grow in 2 to 3 weeks and be ready to snap off a few weeks after that.

Method 2 – Growing in water

• Look at your sweet potato to determine which is the rooting end and which is the sprouting end. The sprouting end has more ‘eyes’ and is usually blunt, while the rooting end is more tapered.
• Stick 3 to 4 toothpicks or short wooden skewers into the sweet potato around the mid point. 
• Place it, rooting end down, in a jar or glass of water. There should be enough water to submerge the bottom two inches of the sweet potato tuber. 
• Change the water every few days. The slips will start to grow in 3 to 4 weeks. 

The best site to grow sweet potatoes

Plant heat-loving sweet potatoes in a spot with full sun and good soil. The root tubers grow best in loamy soil which is fertile and well-drained. Because raised beds warm up early in spring and offer excellent drainage I grow my sweet potatoes in raised beds. If growing in in-ground garden beds, it’s a good idea to pre-warm the soil with black plastic mulch before planting. The black plastic sheeting can be left in place all season long to retain heat and reduce weeds. Just tuck the slips in holes in the mulch – more on this below.

How to plant sweet potato slips: 4 easy steps

Once the last frost date has passed and the soil has warmed to 70 degrees F (20 degrees C), it’s time to plant. Here is a step-by-step guide on how to plant sweet potato slips:

1. Harden off the slips before planting to acclimatize them to outdoor growing conditions. Do this by placing the rooted shoots in full shade and gradually introducing them to increased light over 4 to 5 days. You can place the slips in jars of water or if they’re still attached to the tuber, move the sprouted tuber outside.
2. Prepare the bed by creating hilled rows, called berms. After amending with compost or rotted manure, I rake or hoe the soil into long 8 to 10 inch tall mounds that are about 12 inches wide. These run the length of my raised beds. If using a black plastic mulch to keep beds warm and weed-free, apply it to the soil surface now.
3. Plant each rooted slip 12 inches apart in the berm of soil. To plant the slips in plastic mulch, cut a hole in the plastic and tuck the plant in the soil. Each slip should be planted so the roots and bottom half of the stem are buried under the soil. There should be at least two sets of leaves above ground.
4. Water the soil to help the slips settle in. I don’t use plastic mulch in my garden, but I do apply an organic straw mulch around the slips after planting. As with plastic mulch, this holds soil moisture and reduces weed growth. 

How to plant sweet potato slips in pots

If you’re short on garden space you can still enjoy a crop of sweet potatoes by planting the slips in a pot, fabric grow bag, or other type of container. Understanding how to plant sweet potato slips in containers gives is the first step to healthy plants and large harvests.

Choose a large sized pot or planter and make sure there are drainage holes. The exception to this is fabric grow bags which don’t need a drainage hole as they’re free draining. A 10 gallon container is fine for one plant and a 20 gallon container will hold three plants. Don’t plant too many in a pot as overcrowding impacts root tuber formation and growth. 

Fill the pot with a blend of high quality potting mix and organic matter like compost or aged manure. I use approximately two-thirds potting mix and one-third manure. Plant the slip in the soil so that the bottom half is buried under the dirt and there are still several leaves above ground. Water well and keep the container in a sunny site to promote vigorous growth.

Growing tips

Now that we know how to plant sweet potato slips, let’s look at caring for the plants. Here are three tasks to help ensure a good harvest. 

• Fertilize. A month after transplanting the slips, I side dress the plants with an organic vegetable fertilizer. Avoid high nitrogen fertilizers which promote leafy growth at the expense of root tubers.
• Irrigate. Water deeply every week if there has been no rain. This helps encourage tuber formation. Reduce watering in late summer as too much moisture can cause the roots to split. Container grown sweet potatoes need to be watered more often than garden plants. 
• Weed. Using a hoe, Cobrahead, or your favorite weeding tool, remove weeds as they sprout to eliminate competition for sun, moisture, and nutrients. 

Harvesting sweet potatoes 

As noted above, sweet potatoes are a long season vegetable and need around 90 to 120 days in the garden before harvesting. The sweet potato harvest takes place around the last frost date when the leaves start to yellow or are killed off by a light frost. Use a digging fork to carefully lift the tubers and then cure them for several weeks. Get all the details on harvesting and curing sweet potatoes in our detailed guide.

Now that you know more about how to plant sweet potato slips, you may wish to read more about growing sweet potatoes, as well as other tubers and root crops:

• How to freeze sweet potatoes
• Pro tips for growing sweet potato plants
• Growing potatoes in raised beds
• Two methods for planting beets