When to Harvest Sweet Potatoes for the Best Flavor—and How to Do It

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Timing is everything when it comes to these delicious tubers.

Key Takeaways

• Sweet potatoes are ready to harvest after about 90 to 130 days in the ground.
• Getting this timing right is very important, as harvesting too early or too late can impact sweet potato flavor.
• Keep an eye out for signs that your sweet potatoes are ready to harvest, like yellowing leaves or drooping stems.

Growing sweet potatoes requires patience, but the results are well worth it. In particular, it can often be challenging to know when you should harvest them, since these starchy tubers grow underground. Thankfully, there are a few telltale signs you can watch out for. Here, we asked experts about their tried-and-true methods for harvesting sweet potatoes.

Meet Our Expert

• Jennifer Holston , garden coach and home hydroponics specialist
• Jane Gates , owner and principal designer at Gates & Croft Horticultural Design

Related: How to Plant Sweet Potatoes in Your Backyard, According to Experts

Signs They're Ready to Harvest

Before you go digging up your sweet potato tubers, look for signs of ripeness. "[These vegetables] grow with long, sprawling vines, so it can be tricky to know when it’s time to harvest," admits Jane Gates, owner and principal designer of Gates & Croft Horticultural Design.

Yellowing Leaves : "Keep an eye on yellowing leaves, particularly lower leaves. This is how your sweet potatoes announce they’re ready to be cropped," Gates says.

Mounding Soil: "If you pull the foliage to the side, you'll find that there's a bit of a mound—this is where the potatoes have started pushing the soil up a bit as their tubers form," says Gates.

Drooping Stems : Another thing to watch for are stems that begin to droop and turn yellow, says gardening coach Jennifer Holston.

Check the Neighbors: Holston also suggests finding an outlier sweet potato to examine. "Locate a sweet potato crown closest to the edge," she says. "Move 20 inches away from that crown and the sweet potato patch in the general direction the vine’s headed. Carefully lift a little of the soil at the 20-inch mark using a gardening fork or a hand trowel—no more than 10 inches deep." Then, use your hands to search the soil for sweet potatoes. If none turn up, you can gradually move closer to the crown until you locate one. "If it's small for the variety, delay harvest until right after the first light frost —or before the first hard frost," Holston adds.

When to Harvest

Timing is everything when it comes to harvesting. "Most slip-grown sweet potatoes [are ready to] harvest after 90 to 130 days in the ground," says Holston. "Mark your calendar about a week to two weeks after each variety's recommended harvest date, and dig on that date."

She suggests adding time to help account for less-than-ideal growing conditions like drought, excessive rain, or lack of sun.

It's important to get this timing just right, as it can impact your crop's overall flavor. "Sweet potatoes harvested too early are small, starchy, and less sweet than their mature counterparts," Holston warns. "Late-harvested sweet potatoes become woody, have a shorter storage life, and may sustain frost damage."

There are other potential problems that can arise from delaying a harvest, too. "If you leave tubers too long after the leaves yellow, you might end up with a few giant sweet potatoes and a handful of runts, rather than a full crop of nice-sized, tender tubers," says Gates.

How to Harvest

Time to actually pull those tasty tubers out of the ground! Here's how the experts get it done.

Remove Foliage

It's generally easier to work if all the vines and leaves aren't in the way. In small beds, they can be snipped away with pruners, but if you grew a large amount of sweet potatoes, you could simply mow the foliage away.

Just keep in mind that if you remove the leaves a few days before harvesting, then the skins of the sweet potatoes may toughen up even more.

Mark Your Crowns

Next, mark your sweet potato crowns. "I use sticks and gently place them in the ground," says Holston. "Be careful not to skewer your sweet potatoes! Vine segments begin at the crown—sweet potatoes grow along the vines in clutches."

Start at the Edges

Holston recommends lifting the soil at the edges of the patch first. "This method reduces damage to sweet potatoes and ensures none are left behind," she says. "Once you find a sweet potato or a clutch, harvest the potatoes along the vine to the crown. Repeat until all vines are harvested."

Don't Dig Too Deep

Be careful not to overly disrupt the tubers. "Lift soil no more than 10 inches deep," says Holston. "A very common mistake is digging too close to the roots and bruising or damaging the tubers, reducing their storage quality."

Go Easy

There's no hurry—you've waited all summer, so don't ruin your crop at the last moment with a hasty harvest. "Be patient and gentle while lifting or digging sweet potatoes," says Holston. "They’re easily damaged by tools."

Some experts suggest using your hands to harvest the potatoes to avoid damaging the tubers.

Consider Timing

The weather can have an impact on the efficacy of your harvest. "It’s easiest harvesting on a cloudy day when the soil is moist but not wet," says Holston.

How to Store

Curing sweet potatoes is an important element of the harvesting process, and can help these vegetables achieve the best possible flavor.

"Many fruits and vegetables taste best on harvest day—but not sweet potatoes," says Holston. "Curing them for 7 to 10 days post-harvest turns starches to sugars, ensuring the 'sweet' in your potato."

You'll want this curing process to take place in an environment that has high humidity and temperatures between 80 and 85 degrees Fahrenheit.  After this initial curing is complete, continue curing them for six to eight weeks in a cooler location (perhaps 55 to 60 degrees). Throughout this process, remove and discard any tubers of poor quality.

Related: Should You Refrigerate Sweet Potatoes?

Common Mistakes

There are some pitfalls that can cause your sweet potatoes to die before you even get a chance to harvest them. Here are a few errors that gardening experts often see.

Incorrect Soil

Since sweet potatoes literally grow underground, soil quality is even more important than with other vegetables. "[They] like a light, airy soil mixed with compost to a depth of about a foot," says Gates. "Make sure your soil drains well. Sweet potatoes like slightly moist soil, but they will rot if it becomes too wet."

Root Competition

Roots from competing plants can be disruptive. "Choose a spot to plant or to grow sweet potatoes that isn't near a lot of roots from trees, or the aggressive roots of grapevines," says Gates. "Sweet potatoes don't fare well with root competition. It's easy to forget that too much company underground can distort or even limit tuber production."

Read the original article on Martha Stewart