When To Pick Sweet Potatoes

Knowing when to pick sweet potatoes is the key to a harvest that’s both plentiful and delicious. Get the timing right, and you’ll be rewarded with tubers that store well and taste fantastic. This guide will walk you through all the signs, from the clock to the vine, so you can harvest with confidence.

It’s not as simple as just marking a date on your calendar. Sweet potatoes need a long, warm growing season, and they tell you when they’re ready in a few different ways. We’ll cover the visual cues, the timing guidelines, and the perfect harvesting technique to keep your spuds in perfect condition.

This is your main goal. Hitting this sweet spot means your potatoes will have developed their full sweetness and will cure and store properly. Picking to early means smaller yields and less flavor, while waiting to long can lead to damage from cold or pests.

The Three Main Signs of Readiness

Look for a combination of these indicators. Relying on just one might lead you astray.

The Calendar: Most varieties need 90 to 120 frost-free days from planting. Count forward from when you planted your slips. If you’re getting close to that 100-day mark and other signs are there, it’s a good hint.
The Vine Condition: The leaves and vines will start to yellow. This is the plant beginning to senesce, or slow down. It’s shifting its energy from growing leaves to plumping up the tubers underground.
The Skin Set: This is the most important hands-on test. A mature sweet potato has a firm skin that doesn’t scratch or peel off easily. Try gently rubbing your thumb against a tuber’s skin. If it slips or feels thin, it needs more time.

Why Timing is Everything for Flavor

Sweet potatoes don’t just get bigger as they grow; their starches convert to sugars. This process intensifies as the tubers mature and continues during curing. A potato harvested to early will taste starchy and bland, no matter what you do with it later. The cool soil of late season triggers this sugar conversion, which is why a light frost can be okay, but a hard freeze is a disaster.

The Frost Factor: Your Hard Deadline

Sweet potatoes are extremely sensitive to cold soil. A hard frost that blackens the vines is your absolute signal to harvest immediately, even if the tubers seem a bit small. Cold damage below 50°F (10°C) can cause chilling injury, leading to rot in storage and off flavors. If a light frost is forecast but the ground is still warm, you might have a little more time.

What to Do If an Early Frost Threatens

Cover the patch with thick row covers or blankets overnight.
If frost hits the vines but the forecast warms up again, you can wait a week or so for the tubers to mature further, but keep a close eye.
If a hard freeze is coming, harvest right away. It’s better to have smaller potatoes than rotten ones.

A Step-by-Step Harvesting Guide

How you dig is just as important as when. Sweet potato skins are tender at harvest and bruise easily.

Choose a Dry Day: Harvest when the soil is fairly dry. Wet soil clumps and can make the tubers dirty and more prone to disease.
Cut the Vines First: Use pruners to cut the vines away, leaving about 6 inches of stem above the soil. This makes digging much easier and prevents you from tripping over long runners.
Loosen the Soil: Start digging at least a foot away from the main plant stem. Use a digging fork or a spade, and work gently to avoid spearing the tubers. Loosen the soil in a wide circle around the plant.
Lift by Hand: Once the soil is loose, use your hands to carefully unearth the tubers. Pull them up, brushing off excess soil. Never yank on the stem to lift them.
Be Gentle: Treat them like eggs. Avoid dropping, throwing, or piling them high. Any bruise can become an entry point for decay.

Curing: The Non-Negotiable Next Step

You cannot skip this! Curing heals minor wounds, toughens the skin, and converts starches to sugars. It’s what gives sweet potatoes their classic sweet taste.

Sort First: Separate any badly damaged or cut tubers. Eat these first, as they won’t store well.
Find the Right Spot: You need warmth (80-85°F) and high humidity (85-90%) for 10-14 days. A greenhouse, sunny porch, or a small room with a humidifier works. Some people use a space heater and damp towels in a bathroom.
Lay Them Out: Don’t pack them tightly. Place them in a single layer on racks or newspaper, ensuring good air circulation around each potato.
Then Store Cool: After curing, move them to a cool, dark, and dry place (55-60°F). A basement or cellar is ideal. Properly cured and stored, they can last for many months.

Troubleshooting Common Harvest Issues

Cracked or Misshapen Tubers

This is often caused by uneven watering, especially a sudden heavy rain after a dry period. The tubers grow to fast and split. Consistent moisture is key, especially in the last few weeks before harvest.

Very Small Tubers

This usually means the growing season was to short, the plants were overcrowded, or the soil was poor in nutrients (especially potassium). Ensure you plant slips after the soil is truly warm and give plants plenty of space.

Bitter or Stringy Texture

This can be a varietal trait, but it’s sometimes linked to stress from very hot, dry weather. Again, consistent watering helps prevent this issue and leads to smoother flesh.

FAQ: Your Sweet Potato Harvest Questions

Can I leave sweet potatoes in the ground too long?
Yes. Beyond the risk of frost, overly mature tubers can become woody, crack, or be more susceptible to insect damage in the soil. It’s best to harvest in your ideal window.

What if I harvest a few early as a test?
This is a great idea! Gently dig around one plant to check size and skin set. If they’re not ready, carefully cover the roots back up. The plant will be fine.

How do I know when to dig sweet potatoes in my climate?
In shorter-season areas, choose faster-maturing varieties (like ‘Georgia Jet’). You might need to harvest slightly earlier before frost, and the tubers may be somewhat smaller, but they’ll still be good.

Can you eat sweet potatoes right after digging?
You can, but they won’t be very sweet. For the best flavor, you must cure them first. The starchy flavor of an uncured potato is a real disappointment.

My vines aren’t yellowing, but it’s past 100 days. What should I do?
Check the skin set. If the skins are firm and you’re near your first frost date, go ahead and harvest. Sometimes, especially in very fertile soil, the vines stay green longer.

Mastering the art of when to pick sweet potatoes takes a season or two of practice. Pay attention to the days, watch the weather, and always do the thumb test. With careful digging and proper curing, you’ll enjoy your own homegrown sweet potatoes long into winter. The difference in taste from a store-bought tuber is remarkable, making the wait and the effort completely worth it.