Sweet Potatoes: How to Harvest & Cure

Sweet potatoes are a delicious and healthy vegetable that’s a must-have in my garden. I love growing sweet potatoes because they’re a low-maintenance crop with a gorgeous leaf ground cover, and after harvest, they store well for months so I’ll have homegrown sweet potatoes for fall and winter cooking. The key to a long-storing supply is harvesting them at the correct time, as well as curing them properly. This article provides expert advice and tips on how to harvest sweet potatoes so that you can enjoy this amazing vegetable for months to come.

Sweet potatoes (Ipomoea batatas) are not potatoes at all, in the french fry sense, but rather are members of the morning glory family (Convolvulaceae). This difference is most evident in their leaving habits: potato plants resemble short tomato plants, while sweet potatoes have long vines with heart-shaped leaves, like the trailing morning glory.

I’ve grown sweet potatoes for many, many years, and have learned things about the crop that goes far beyond the typical shortfall of advice you’ll find on the interwebs. Sweet potatoes are an absolute delight to grow, and I love that I can choose varieties other than the standard workhorse, but sort of ho-hum orange Beauregards that you usually find at the grocery store.

Indeed, thanks to growers across the U.S., we have access to tasty varieties, such as Okinawan (or Hawaiian), Murasaki, Hannah, and Satsuma-imo, and more, whose flavor palates range from sweet and creamy to nutty and earthy. And also many colors of the rainbow: white, yellow, orange, red, purple, and pink!

I also want to take a moment here to make a sales pitch for the broader use of sweet potatoes in your cooking repertoire, if you don’t already. I know sweet potato pie and sweet potato casserole spring immediately to mind for most people.

But I love them as a straight-up replacement for standard white potatoes in savory — yes, savory! — preparations. Sweet potato fries. Spicy roasted sweet potato chunks. And my favorite of all: baked sweet potatoes with crispy skin and creamy interior, topped with black beans, salsa, and guacamole. Best WFH lunch ever!

So as you’re preparing to harvest your crop this year, I hope you’ll look at these beautiful vegetables as a dinner option, too.

When are Sweet Potatoes Ready to Harvest?

Some sources might tell you to wait until leaves on the vines turn yellow, darken, or die back. That’s probably great advice in some climates, but in mine, my sweet potato vines grow and grow and grow in a lush green carpet until first frost, which is far too late for well-formed, properly-sized sweet potatoes.

Instead, I follow the maturity dates recommended by the growers. I mark the planting date on my calendar, and count forward and mark the approximate harvest date, too. Since I grow different varieties, they often have very different harvest dates, so I’m careful to note what’s what and when.

If the growing season had less than ideal weather — e.g., drought and high temps — I usually delay harvest until the weather cools and there have been several weeks of restorative rainfall. (That is, not several weeks of constant rain, just a stretch of rain and dry, to give the plants one last chance for a growth spurt.)

It’s a little bit risky, the delay, because sometimes the potatoes were actually ready to harvest on the original date, and the extra time let them grow into monster size, lol (see photo above). But sometimes the delay also means a much larger harvest because all of the potatoes will get time to grow to maturity.

What to Do About the Sweet Potato Leaves?

A healthy sweet potato crop will consist of numerous very long vines that are packed with leaves. They’re essential for nourishing the plant during growth, but at harvest, you have some options for the generous abundance of leaves. Note that sweet potato leaves are actually completely edible to both humans and furry woodland creatures.

1. Pick and consume them. Sweet Potato leaves have a strong, slightly bitter taste, so while you can absolutely (and safely) use them as a salad green, many people use them as a substitute for spinach or kale in cooked recipes. Briefly sauteeing or lightly steaming them removes the bitterness while retaining their considerable health benefits. Or incorporate them into your morning smoothie or green juice.
2. Strip the leaves off the vines for composting. This is a fabulous use for these materials, as they count as the “green” in your green/brown composting balance.
3. If neither of those things interests you — or if you have many, many vines to deal with from multiple plantings, as I do — here’s a suggestion to consider. My area has a large deer population, and deer LOVE sweet potato leaves.

About a week before harvest, I remove the fencing around my sweet potato plot and let the deer have at it. They will strip those vines clean! With the leaves gone, the bed will have much better visibility and it will be much easier to handle the vines, locate the crowns, and figure out where to dig.

Conditions for harvest

Ideally, for a couple of reasons, harvest day should be cloudy or overcast. First, to provide a more pleasant condition for us humans, but also because newly harvested potatoes are a little bit tender and can be prone to sun-scald. But even if the sun is blazing, you can take care to immediately move the sweet potato clusters to a shady area.

Avoid attempting harvest after a good rain, when the soil is particularly wet and muddy. It’s very difficult to extract potatoes in muddy conditions. And super easy to accidentally damage the tubers.

And at the opposite end of the scale — although definitely better than muddy conditions — avoid harvest when the soil is bone dry several inches down and hard as a rock.

Harvest is easiest when the soil is nice and loamy and just ever so slightly damp. And if you can dig into the bed and “shovel” with your fingers, that’s :chef’s kiss:

Of course, perfection rarely happens, so use the guidelines here and your own best judgment to pick the day, if you have the option (sometimes, you don’t and you just have to go for it. Been there, lol.)

Some general advice before getting started

One of the first things I learned about sweet potato growth many, many years ago is that sweet potatoes only form at the crown of the plant (the central stem): one big batch per plant and done.

This is a common and unfortunate misconception.

Sweet potato vines can and often do root at nodes anywhere along their lengths, and if those roots find their way into the soil, they’ll produce a cluster of sweet potatoes. This can happen anywhere along the vine … or it might not happen at all. So, there will be the big primary cluster at the crown, and then sporadic satellite clusters along the vines that branch out from that central stem.

What do I mean by “cluster”? Sweet potatoes grow from the roots of their plants. Unlike, for example, a carrot, which is the product of a single root, a sweet potato plant produces numerous roots, and each root can become a full sweet potato. So, the sweet potatoes produced from a single plant are joined together by the root system and all are attached to the plant.

I often see videos of gardeners at harvest gathering up the masses of vines and pulling them off the ground, to follow the vines back to the crowns. This action unfortunately rips the vines away from the satellite sweet potato clusters. While it doesn’t harm the cluster, it does make it nearly impossible to find from above ground.

I recommend one of two big-picture approaches to harvesting sweet potatoes:

1. Plan to thoroughly turn over the entire sweet potato bed after removing the vines to locate all of the clusters, or
2. Start at the tips of the vines, and begin gently tugging on the vine, looking for spots where the vine has rooted to the ground, and carefully digging around those spots. Work your way up to the crown a little at a time.

Either way, it will be time-consuming, so if you have to spread your harvest out over the day or two days, don’t hesitate to do so. I’d rather take my time than miss sweet potatoes!

Tools

Because you’re digging fairly blindly, one of the priorities should be avoiding damaging the tubers. So, you should pick a digging tool that you’re comfortable with.

Some sweet potato clusters can be quite large and lodged deep in the ground. You’ll likely need a long-handled implement of some sort.

Many gardeners use a spading fork, as it easily penetrates the soil to break up and separate clumps of dried soil. It’s also my tool of choice, although accidents do happen!

You can also use a spade shovel. Or get up close and personal with a hand shovel, which is the best method for avoiding damage to the sweet potatoes, as you can work layer by layer to free the tubers from the ground.

Find the Crown (the central plant)

If you happened to have followed my advice for planting Okinawan Sweet Potatoes, then you will have marked each plant’s crown with a stake at planting time, so now at harvest time, you can easily find the main cluster of sweet potatoes amongst all of the vines and leaves.

But, barring that, you should take a few moments to find the crowns now, before removing vines. It’s very easy to lose track of the crowns and, therefore, the main cluster of sweet potatoes. The vines might drop thin roots along the plant.

The crown will be the only thick plant stem that goes into the ground:

Once locating the crown, you can either dig up those sweet potatoes now, or mark the spot to come back to it later.

Inspect the vines

As mentioned above, your sweet potato vines could have produced satellites of sweet potato clusters anywhere along their lengths. Test the vines by carefully pulling up on them, looking for spots where they’ve significantly rooted to the ground. Either mark these spots with a stake to return to later, or dig each of them up as you go.

Get digging!

You’ve done the legwork, you’ve located the crowns and potential spots for satellite clusters. Now it’s time to dig in!

Mentally visualize what a cluster of sweet potatoes might look like and start digging in a wider berth around where they might be. I’m not gonna lie: there’s a bit of guesswork involved, and I’ve accidentally damaged my share of potatoes when they were growing in unexpected places.

So, it’s better to start wider and slowly work your way in. Once you spy a potato, carefully begin pushing aside the soil to reveal the entire cluster. Then gently tug on the vine to release it from the ground.

How to cure sweet potatoes

It’s important to cure your sweet potato crop so that the tubers will last several months. Curing heals cuts and blemishes, thickens the protective layer of skin, and converts starches to sugars, which optimizes flavor.

Once harvested, separate the sweet potatoes and cut them away from the connecting stems. Carefully brush off excess soil. Do not wash them. Snap off any roots or sprouts. Then load them up and move them to their curing location.

Ideal conditions for curing call for high humidity and sustained temperatures in the 80s (Fahrenheit). I cure my sweet potatoes in my garage. Typical harvest time here occurs in late September, when temps are still in the 80s and 90s. Humidity is always an issue in the Ohio Valley, so I’m never short on humidity!

You can also use a greenhouse. Or imitate a greenhouse set up by stashing your sweet potatoes in plastic bags. Cut several holes in the bags for ventilation and keep them in a very warm location.

Curing should take 1 to 2 weeks.

How to store sweet potatoes

Store the cured tubers in a cool, dry, well-ventilated space in temperatures ranging from 50-60ºF.

Frequently Asked Questions

How can I tell if I’ve left my sweet potatoes in the ground for too long?
Overmature sweet potatoes tend to crack or become too fibrous to be tasty. They can also grow quite large! Regularly inspect your crop as the harvest period approaches, to avoid leaving them in the ground for too long.

What should I do if it rains near my harvest time?
If you can’t avoid harvesting sweet potatoes in wet conditions, try to let the harvested potatoes dry out as much as possible before storing. Don’t wash them before storage.

Why do sweet potatoes need to be cured?
Curing allows the sweet potatoes to heal from any damage that might have happened during harvesting, and it helps to convert starches into sugars, enhancing the sweet taste.

What can I do if my sweet potatoes start to sprout during storage?
If sprouts are small, they can be removed and the sweet potato can still be eaten. However, large sprouts indicate the sweet potato is aging and may have become woody or dehydrated.

Can I eat sweet potatoes immediately after harvest?
Yes, you can eat them immediately. However, they’ll taste sweeter if you allow them to cure, which lets the starches convert to sugars.

How do I know if a sweet potato is bad?
A bad sweet potato will have soft, mushy flesh and a sour smell. If you see any signs of rot or mold, it’s best to discard the sweet potato rather than trying to cut it out.

How should I store sweet potatoes after curing?
Sweet potatoes should be stored in a cool, dark, well-ventilated place. Ideal storage temperature is between 55-60°F. Properly stored, they can last for several months.

I hope this article on how to harvest sweet potatoes has given you helpful strategies for approaching the extraction of these beautiful, hidden garden jewels, and storage advice to enjoy a long winter of delicious cooking!