How to Start Sweet Potato Slips

Here's how to grow sweet potato slips in soil or water.

Growing sweet potatoes in your garden is easy and rewarding. The best way to plant sweet potatoes is to start with slips, which are short stems with a few leaves and a few roots that grow from a sweet potato. You can easily grow slips in soil or water with a few basic supplies and a little patience. Use this step-by-step guide to start sweet potato slips that you can plant in your garden.

Tuber or Not Tuber

Unlike most veggies, sweet potatoes are not started from seed; neither are they started from whole tubers or chunks of the tuber like potatoes. That’s because sweet potatoes are not tubers—which are modified stems—but a different type of storage organ called a tuberous root.

sweet potato in water with green sprouts

Miyeon Lee/ Getty Images

When to Start Sweet Potato Slips

Aim to plant your sweet potato slips in the ground about three weeks after your area's last frost date in spring, when the soil has completely warmed up. Sweet potatoes are quite sensitive to cold, so you don’t want to rush this. It will take 6-8 weeks for the slips to develop, so count back about about 10 weeks before your last expected frost and that’s the time to start your slips.

If some of your slips are ready a bit before planting time, it’s easy to hold them in a jar of water for a few week (they will continue to make roots). Plus, sweet potatoes will keep producing new slips over a period of a few weeks, so this gives you some flexibility.

What You’ll Need to Make Slips

  • Sweet potato: Make sure it’s healthy and hasn’t been treated or waxed to prevent sprouting or you will have frustrating results. Your best bet is to buy organic. A single sweet potato will usually produce 10 to 20 good slips, so if you want to plant more than that in the garden, you will need additional starter sweet potatoes.
  • Sand or potting soil
  • Container with drainage hole. It should be large enough to lay the sweet potato on its side but needn’t be very deep—3 or 4 inches will do.
  • Clean straw to help retain moisture. This isn’t absolutely necessary, it can help encourage the shoots to develop.

How to Grow Sweet Potato Slips in Soil

  1. Wash the sweet potato(es) thoroughly.
  2. Moisten your potting soil or sand and fill your container.
  3. Set your sweet potato(es) lengthwise in the pot so that the lower half is buried with soil (or sand).
  4. Water to seat the soil around the sweet potato. Keep the soil moist but not soaking wet. A mister can come in handy here.
  5. If you are using straw, cover the sweet potato and soil surface with a light layer.
  6. Place the pot in a warm, sunny room. 
  7. After about a month, you should start to see shoots sprouting from the tuberous root. Most will come out of one end—the sprouting end. You may see roots develop from the opposite end.
  8. Once the shoots are 5-6 inches long, remove them—just break them off where they come out of the sweet potato—and place them in a jar of water in a sunny window or under grow lights until you’re ready to plant. The slips will continue to develop roots in water and the original sweet potato will continue to produce slips for a few weeks.

Starting Sweet Potato Slips in Water

Slips can also be started by submerging a part of the sweet potato in water, but this method usually takes a bit longer.

  1. Examine the sweet potato and determine which is the sprouting end—it will have more nodes or “eyes” than the opposite end. If you can’t tell, put the sweet potato in a warm room for a few days—the nodes should become more apparent.
  2. Push three or four toothpicks into the sweet potato to hold the sprouting end above the water. 
  3. Set the lower end (the rooting end) in a jar of water and wait for your slips to form. It may take several weeks.
  4. Detach them and place them in water where they will develop roots.
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