Learning how to grow sweet potatoes is surprisingly easy – just a few plants provide a plentiful harvest. Sweet potatoes need a long warm growing season, are heat-tolerant and drought-resistant, and have very few pests or diseases. All of this makes them perfect for growing in the low desert of Arizona (yay!) Here are eight tips for how to plant, grow, and harvest sweet potatoes.
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8 Tips for Growing Sweet Potatoes
1. Plant sweet potatoes at the correct time
Plant sweet potatoes 2-3 weeks after the last spring frost, when the soil temperature is at least 65℉.
In the low desert of Arizona:
- Begin making sweet potato slips indoors from January through April.
- Plant sweet potato slips outdoors from March through June.
2. Prepare soil correctly before planting sweet potatoes
Sweet potatoes need well-draining slightly-acidic soil. Amend clay soils heavily with compost. Soil should be worked to a depth of at least 8-10 inches. Sweet potatoes can also be grown in raised beds or large containers. Plant in an area with full sun and/or afternoon shade in the low desert.
3. Plant sweet potato slips
Sweet potatoes aren’t grown from seed like many other vegetables. Rather, they are started from slips – rooted sweet potato shoots grown from a mature sweet potato. Grow your slips from sweet potatoes or purchase slips.
Looking for more information about how to grow sweet potato slips? This article about how to grow sweet potato slips will help.
Most varieties of sweet potatoes do well in the long growing season of the low desert. In higher elevations or places with shorter growing seasons, choose from quickly-maturing varieties such as ‘Beauregard’ and ‘O’Henry’.
Plant rooted slips deeply, burying slips up to top leaves. Space sweet potato plants 12-18 inches apart. Water well and feed with a starter solution high in phosphorus (if your soil lacks phosphorus) to ensure the plants root well.
4. Allow vines to grow for larger sweet potatoes
Occasional small harvests of greens to eat is fine, but do not prune back vigorous vines for the best-sized harvests. The size of the sweet potatoes is determined by the amount of sunlight the leaves receive. More sunlight and leaf surface area that receives sun means larger sweet potatoes.
If space is an issue, consider growing vines vertically up a trellis to allow sunlight to reach the leaves and produce larger sweet potatoes.
Check longer vines occasionally and lift them up to keep them from rooting in the soil along the vines. Additional rooting will take energy away from the main tubers and instead create many undersized tubers.
In this article, learn more about using cover crops during summer to improve garden soil.
5. Water deeply, less often
Deep watering is crucial for sweet potatoes during hot dry periods. However, it is important to let soil dry out somewhat between waterings. Sweet potatoes tolerate dry conditions better than soggy ones.
6. Harvest sweet potatoes at the right time
Here are a few things to look for before harvesting sweet potatoes:
- The longer a crop is left in the ground, the higher the yield.
- Sweet potatoes may be ready to harvest between 90-120 days after planting.
- Harvest when tubers are at least 3 inches in diameter.
- Harvest sweet potatoes before the first fall frost.
- When the leaves and vines begin turning yellow, production is slowing down. Leave them in the ground a little longer for the largest tubers.
- Once the top growth has died down, remove foliage and harvest.
7. Harvest sweet potatoes correctly
Once you have decided to harvest the sweet potatoes, cut back vines and loosen soil around the plant with a spade fork. Carefully find the primary crown of each plant, and use your hands to dig up the tubers. Shake off any excess dirt, and handle tubers carefully to prevent bruising. Keep harvested sweet potatoes out of direct sunlight. Do not wash sweet potatoes until ready to use for longest storage life.
8. Cure and store sweet potatoes correctly for the longest storage life
To cure sweet potatoes, set potatoes in a single layer (not touching) in a warm (about 80℉) humid area for 10-14 days. Curing allows cuts and bruises to heal and helps the starches inside the sweet potatoes convert to sugars.
HOT CLIMATE SWEET POTATO CURING TIP:
Put the sweet potatoes in a single layer in a plastic grocery sack (cut a couple of holes in the bag for ventilation) to trap moisture in a warm spot INSIDE your house. Outside temperatures may not be the right temperature for sweet potatoes to cure properly.
The curing process is complete if the skin remains intact when the sweet potatoes are rubbed together. Sprouting will occur if potatoes are cured too long. After curing, throw out or immediately use any bruised potatoes.
Store cured sweet potatoes in a cool (about 55-65℉ if possible) dry area for the longest storage.
HOT CLIMATE SWEET POTATO STORAGE TIP:
If stored above 70°F, the storage life of sweet potatoes is shortened considerably. When outside temperatures are cool, store sweet potatoes in the garage in a box with individual potatoes wrapped in newspaper. Once temperatures heat up, bring the box inside to your coolest room. Check potatoes often and use any right away that show signs of sprouting or rotting.