Sweet potatoes have become one of the most common vegetables in gardens and kitchens around the world. Originating from South America over 5000 years ago, these tender warm-season annuals require careful timing and conditions to flourish and reach their full potential.
Growing them is possible in practically all the regions and weather conditions, which makes them quite accessible. Today, let us talk about when they should be harvested, but also about other relevant information about sweet potatoes.
Key Takeaways:
- Harvesting should ideally be done in dry weather before the first frosts of fall to prevent disease and damage.
- Curing sweet potatoes at 80-85°F with high humidity (85-90%) for about two weeks is vital for enhancing their natural sweetness.
- A gentle approach is crucial when harvesting sweet potatoes to avoid damaging their delicate skins.
Signs of Maturity
The lifecycle of a sweet potato from slip to tuber is a fascinating process, typically spanning about four to five months. Gardeners eagerly await the late summer and fall, when the first signs of maturity begin to show.
The foliage of the sweet potato plant, lush and vibrant through the growing season, provides the clearest indicator of readiness for harvest as it turns yellow and starts to die back. This natural progression signals that the tubers below have developed their full size and flavor, making it the ideal time to begin the harvest.
Sweet potatoes mature in stages, with the initial three months critical for the development of large, tasty tubers.
| Stage | Duration | Signs of Progress |
|---|---|---|
| Slip Planting | Day 0 | Slips begin to establish and grow. |
| Early Growth | 0-3 months | Visible growth of vines and leaves, establishment of root system. |
| Mid to Late Growth | 3-4 months | Foliage thickens, tubers begin to form and expand underground. |
| Maturity Indication | 4-5 months | Tubers reach full size, enhanced flavor profile. Foliage turns yellow and starts to die back. |
| Harvest | Late summer to fall | Harvested tubers ready for curing and storage. |
These storage roots, unlike common tubers, grow from slips—sprouted shoots planted after the last frost when the soil has warmed to at least 65°F. The plants thrive in full sun, requiring at least six hours of direct light daily, and are sensitive to drought in the early stages of growth.
As the days to maturity range from 85 to 120 days, the gardener’s patience is rewarded with a yield of approximately 15-30 lbs per 10-foot row, depending on the care and conditions provided throughout the season.
Optimal Harvesting Conditions
Harvesting sweet potatoes at the right time and under the right conditions is not just beneficial—it’s crucial for maximizing the quality and longevity of your crop. The ideal harvest time is during a spell of dry weather, preferably before the first frosts of fall make their appearance. This specific timing is critical for several reasons:
- Disease Prevention: Dry conditions help minimize the risk of fungal diseases and rot, which thrive in moisture. Harvesting in dry weather reduces the likelihood of these issues, ensuring that the sweet potatoes are in the best condition when harvested.
- Tuber Quality: The quality of sweet potatoes is at its peak just before the onset of cold weather. The tubers have had ample time to mature and develop their full flavor and nutritional profile.
- Damage Avoidance: Frost can damage sweet potatoes, affecting their texture and taste. By harvesting before the frost, you ensure that the tubers remain undamaged and suitable for storage.
For those growing sweet potatoes in containers, the timeline might be slightly adjusted. Typically, container-grown sweet potatoes are ready for harvest around four months after planting. The key indicator for readiness, much like their ground-planted counterparts, is the yellowing and dying back of the foliage.
This visual cue is a reliable sign that the tubers have reached maturity and are ready to be harvested. It’s important to note that harvesting too early can lead to underdeveloped tubers, which are smaller and less flavorful. Patience and timing are crucial elements in the cultivation of sweet potatoes, whether in the ground or in containers.
| Factor | Ground-Planted Sweet Potatoes | Container-Grown Sweet Potatoes |
|---|---|---|
| Ideal Harvest Time | Before the first frosts of fall | Around four months after planting |
| Weather Conditions | Dry weather | Dry weather |
| Indicators of Maturity | Foliage turns yellow and dies back | Foliage turns yellow and dies back |
| Risks of Early Harvest | Smaller, less flavorful tubers | Smaller, less flavorful tubers |
| Post-Harvest Handling | Cure in dry, high humidity conditions | Cure in dry, high humidity conditions |
Harvesting Technique
The technique used in harvesting sweet potatoes is as important as the timing.
Gentle Extraction
Gently insert the garden fork or spade into the soil at a slight distance from the main stem of the sweet potato plant. This precaution helps avoid piercing the tubers. Lever the soil gently to lift the sweet potatoes to the surface.
If the soil is particularly dense, you may need to work around the plant in a circle, loosening the earth gradually until the tubers can be lifted out with minimal resistance.
Handling and Initial Cleaning
Once lifted from the soil, handle the sweet potatoes with care. Their skins are very delicate at this stage and can be easily bruised or scratched, leading to potential entry points for disease during storage.
Shake off any loose soil gently, but avoid washing the tubers, as moisture can promote rot. If there’s stubborn soil, it’s better to leave it until after the curing process, as the skin will harden and make cleaning easier and safer for the sweet potato.
Curing Process
The curing process is vital for several reasons. It helps heal any minor damage to the skin, reduces the potential for storage diseases, and enhances the sweet potatoes’ natural sweetness. To cure sweet potatoes, space them apart in a single layer in a well-ventilated, dry area with high humidity, ideally around 85-90%.
The temperature should be kept around 80-85°F. This environment can be challenging to achieve in some climates, so alternatives like using a greenhouse, a warm shed, or even a spare room in your house can be considered.
The sweet potatoes should remain in these conditions for about two weeks. During this time, the skin will harden, and the flesh will become sweeter and more flavorful.
Post-Curing Handling
After curing, inspect the sweet potatoes for any signs of damage or disease. Remove any tubers that show signs of rot or damage to prevent them from affecting the rest of the crop during storage.
The cured sweet potatoes are now ready for storage in a cool, dark place where they can be kept for several months.
Storage
After curing, sweet potatoes require careful storage to maintain their quality.
Temperature and Humidity
The optimal storage temperature for sweet potatoes is between 55-60°F (13-16°C). This range is slightly warmer than a typical refrigerator but cooler than room temperature, making locations like basements, cellars, or a cool pantry ideal for storage. The humidity level should also be high, around 85-90%, to prevent the tubers from drying out.
These conditions mimic the sweet potatoes’ natural storage environment in the ground, helping to maintain their texture and flavor.
Light and Ventilation
Sweet potatoes should be stored in a dark place to prevent them from sprouting or developing green spots, which can make them bitter and less palatable. Good ventilation is also important to prevent the accumulation of ethylene gas, which can accelerate spoilage.
A well-ventilated crate, basket, or even a cardboard box with holes can be an excellent storage container.
Preparing Sweet Potatoes for Storage
Now let us take a look at ways to prepare them for storage.
Inspection
Before storing, inspect each sweet potato carefully. Discard any tubers with signs of damage, rot, or disease, as these can affect the rest of the stored sweet potatoes. Only healthy, undamaged sweet potatoes should be stored to ensure the longevity of your harvest.
Cleaning
It’s important not to wash sweet potatoes before storage, as the moisture can promote mold growth. Instead, gently brush off any remaining soil after the curing process. If you must clean them, do so right before cooking, not before storage.
Wrapping
Wrapping sweet potatoes individually in newspaper or brown paper can help maintain the ideal humidity around each tuber and provide a barrier against any potential pests. This method also makes it easier to inspect the sweet potatoes periodically and remove any that start to spoil without disturbing the entire storage setup.
FAQs
Can you eat sweet potato leaves?
Yes, sweet potato leaves are edible and nutritious. They can be cooked and eaten like spinach, offering a rich source of vitamins, minerals, and antioxidants. Ensure they are washed thoroughly before cooking.
Can you eat sweet potatoes straight from the garden?
Yes, you can eat sweet potatoes straight from the garden, but it’s recommended to wash and cook them first. However, uncured sweet potatoes will have a shorter shelf life and may not be as sweet or flavorful as cured ones.
What happens if you don’t cure sweet potatoes?
If you don’t cure sweet potatoes, they may not develop their full sweetness and can be more susceptible to storage diseases and shorter shelf life. Curing helps to heal any surface damage, reduces the risk of decay, and enhances flavor.
Summary
Knowing when to harvest sweet potatoes is crucial for gardeners aiming to achieve the best yield, flavor, and storage life from their crop. The optimal time for harvesting is when the foliage begins to turn yellow and die back, typically occurring in late summer to fall, before the first frosts.
Timing ensures that the sweet potatoes have matured properly, offering the richest taste and nutritional value. It’s also essential to handle the sweet potatoes gently during harvest to prevent damage to their delicate skins, followed by a proper curing process to enhance their sweetness and extend their shelf life.