When to Harvest Sweet Potatoes

Sweet potatoes an easy crop to grow if you’re in a warm climate. They are my favorite thing to grow and we love to harvest sweet potatoes when they are HUGE! However, this guide will help you to know when to harvest sweet potatoes at whatever size is your favorite.

It’s important to plant at the right time and to know when to harvest sweet potatoes.

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Count out Days to Maturity and Use that as a Guide to Know When to Harvest sweet Potatoes

One of the clues that will help you know when to harvest sweet potatoes is the variety. Each variety has an average “days to maturity” or time when the crop is mature and ready to harvest. 

For example, I grow Beauregard sweet potatoes. The days to maturity for a Beauregard sweet potato is 90 days. Since I planted the sweet potato slips at the beginning of June, they should be ready for harvest around the first week of September, 90 days after planting.

This is a rough estimate date and not an absolute. A cold climate may need more time to achieve maturity.

Here are a few of the most popular varieties of sweet potatoes and their days to maturity:

• Purple Majesty 100 days
• Luminance 85 days
• Covington 90 days
• Murasaki 105 days
• Beauregard 90 days
• Mahon Yam 90 days
• Bayou Belle 90-100 days

You can harvest sweet potatoes AFTER they reach the normal days to maturity if you want larger sweet potatoes. Last year, I was busy with a lot of other garden projects and neglected the sweet potatoes even after I knew they were ready. 

We harvested about 25 days after they were at maturity. 

Is Flowering a Sign Sweet Potatoes are Almost Ready?

I remember when I first started growing sweet potatoes, I read that flowering was a sign they are nearly ready for harvest. I have found that to be true with caveats. Unfortunately, from what I hear, not all sweet potato vines bloom so this may not be a reliable method of telling when a harvest is ready.

Personally, mine bloom every year I grow them. I have many flowers some years, and few flowers in other years. The flowers are more likely to bloom in a hot and humid climate like mine.

I usually wait a few more weeks after they bloom to harvest the sweet potatoes. Sweet potatoes are in the morning glory family and the flowers look like a morning glory in a trumpet shape. 

The Beauregard sweet potato blooms are lavender color with a dark purple center.

Leaves of the sweet Potato Vines are yellowing at the stem

One more clear sign that sweet potatoes are at maturity is if the leaves are starting to yellow or turn a more bronze color where the main stem comes out of the ground. 

If you would like to see a real life version of what this looks like, you can check out the video of my sweet potato harvest. 

The leaves will NOT yellow and die like regular potatoes.  The vine will still be living even at maturity.

Check if the area is bulging up

Another more visible sign is if the soil is bulging where the main stem meets the ground. You may even be able to see sweet potatoes poking up! Mine usually poke up a few inches above the surface of the soil and the rest of the potatoes are buried below ground.

Remove the Soil or Pull them out

The most obvious way to tell sweet potato plants are ready for harvest is pulling them out of the ground! If you don’t have many plants, the better option would be to remove some of the soil around the main stem of the plant.

You’ll be able to view the size of the sweet potatoes and if you aren’t happy with it, you can always cover them back up with soil and let them keep growing.

When to Harvest Sweet Potatoes with a short growing season

If you have a short growing season or a cooler climate you will need the ENTIRE frost free time to grow those sweet potatoes. Sweet potatoes love heat, so I recommend starting them in a high tunnel or building a low tunnel that is protected. 

Any additional heat and humidity is usually beneficial, especially if you live in more of a desert area with cold nights. 

You’ll need to harvest sweet potatoes before the soil temperature drops below 50ºF. Any temperatures below this will damage sweet potatoes. If a frost is imminent or temperatures are chilly (near frost), harvest before the weather hits.

Damage to sweet potatoes at harvest is more likely when the soil is wet. Sometimes sweet potatoes will cure over these spots. However, the more gentle you can be with the harvest, the more quality the sweet potatoes will be.

If the sweet potatoes are not damaged they are less likely to rot in storage.

Conclusion

Here are the ways to check if a sweet potato plant is mature and the roots are ready for harvest:

1. Count out Days to Maturity and Use that as a Guide to Know When to Harvest
2. The leaves start to yellow or turn a bronze color where the main stem meets the ground.
3. The soil is bulging up and sweet potatoes may be visibly poking out of the ground at the main stem.
4. Remove soil around them to see if they are ready, or if you have enough plants dig them up at check!
5. In cold climates, the full growing season is needed to reach maturity. In that case you must harvest before soil temperature drops below 50ºF so there is no damage to the potatoes.