If you’re planning your Tennessee garden, knowing when to plant sweet potatoes is the first step to a great harvest. Getting the timing right is crucial for this warm-season crop, and this guide will cover the optimal planting times for success across the state.
Sweet potatoes love heat and are very sensitive to cold. Planting them too early in cool soil can stunt their growth or even kill the young plants, called slips. Planting too late shortens their growing season, which they need to produce those tasty tubers you’re after. Let’s break down the perfect schedule.
When to Plant Sweet potatoes in Tennessee
For most of Tennessee, the ideal window for planting sweet potato slips is from early May through mid-June. The single most important rule is to wait until the soil is warm—at least 65°F at a 4-inch depth—and all danger of frost has passed.
Air temperatures should be consistently warm, both day and night. A good visual cue is when the oak leaves are about the size of a squirrel’s ear. Here’s a more detailed regional breakdown:
- West Tennessee (Zones 7b-8a): The warmest region can often start planting in late April to early May. The soil warms up quicker here along the Mississippi.
- Middle Tennessee (Zones 7a-7b): Aim for early to mid-May. Watch the weather for any late, unexpected cold snaps.
- East Tennessee (Zones 6b-7a): The higher elevations mean a later start. Mid-May to early June is safest here to ensure the soil is adequately warm.
Why Timing is Everything for Sweet Potatoes
Sweet potatoes are not just frost-sensitive; they languish in cool soil. Planting into soil below 60°F can lead to “soil sickness,” where the slips fail to root properly and just sit there. This delays growth and makes plants more vunerable to disease.
Conversely, planting by mid-June ensures they get 90 to 120 frost-free days they need to mature. The long, hot summers of Tennessee are actually perfect for them once they get going. The vines thrive in the heat, and the tubers swell in the warm soil of late summer and early fall.
Preparing Your Garden for Planting
Good preparation makes all the difference. Start a few weeks before your planned planting date.
- Choose a Sunny Site: Select a spot that gets full sun—at least 6 to 8 hours of direct sunlight daily.
- Loosen the Soil: Sweet potatoes need loose, well-draining soil to form nice-shaped roots. Till or dig the area to a depth of 10-12 inches.
- Amend the Soil: They prefer a slightly acidic to neutral pH (5.8-6.5). Avoid high-nitrogen fertilizers, which promote leafy vines instead of roots. Mix in compost or a low-nitrogen, phosphorous-rich fertilizer.
- Form Raised Rows or Hills: Mound the soil into rows about 8-12 inches high and 3 feet apart. This improves drainage and warms the soil faster, giving your slips a head start.
How to Plant Sweet Potato Slips Correctly
You can buy slips from a garden center or grow your own from a sweet potato. When you’re ready to plant, follow these steps:
- Harden Off Slips: If your slips were grown indoors or shipped, acclimate them to outdoor conditions over 5-7 days.
- Water Before Planting: Give the slips a good drink an hour or two before putting them in the ground.
- Plant Deeply: Make a hole in the prepared hill. Bury the slip so that only the top leaves are above the soil. Roots will form along the buried stem.
- Space Them Out: Plant slips 12-18 inches apart within the row. This gives each plant room to spread.
- Water Thoroughly: After planting, water them in well to settle the soil and eliminate air pockets.
Caring for Your Growing Sweet Potatoes
Sweet potatoes are relatively low-maintenance once established. For the first few weeks, keep the soil consistently moist to help the roots establish. After that, they are quite drought-tolerant, but deep watering during very dry periods will improve yeild.
- Weeding: Weed carefully early on. Once the vines spread and cover the ground, they will shade out most weeds.
- Feeding: If needed, a side dressing of a potassium-rich fertilizer (like potash) in mid-summer can benefit tuber development.
- Avoid Overwatering: Too much water, especially late in the season, can cause the roots to crack or rot.
When and How to Harvest in Tennessee
Your sweet potatoes are ready to harvest about 90-120 days after planting, typically from late September through October. The key sign is when the leaves and vines begin to yellow and wither. Always harvest before the first fall frost, as frost can damage the tubers.
- Use a garden fork to carefully loosen the soil beside the hill.
- Lift the primary crown of tubers gently to avoid bruising or spearing them.
- Shake off excess soil, but do not wash the roots at this stage.
Curing and Storing Your Harvest
This final step is essential for sweet, storable sweet potatoes. Curing heals minor wounds and converts starches to sugars. For about 10-14 days, keep the harvested roots in a warm (80-85°F) and humid place, like a porch or garage. After curing, store them in a cool (55-60°F), dark, and well-ventilated place. Properly cured and stored, your Tennessee-grown sweet potatoes can last for many months.
Common Problems and Solutions
Even with perfect timing, you might encounter a few issues. Here’s what to watch for:
- Deer & Voles: Deer may eat the vines; fencing is the best deterrent. Voles can tunnel and eat the tubers; keep areas clear of heavy mulch near harvest.
- Root-Knot Nematodes: These microscopic pests cause knobby, damaged roots. Rotate your sweet potato bed each year to help prevent them.
- Fungal Diseases: Proper spacing for air flow and avoiding wet foliage can prevent most fungal problems like leaf spot.
FAQ: Sweet Potato Planting in Tennessee
Can I plant sweet potatoes from the grocery store?
You can sprout them for slips, but it’s not always reliable. Store-bought potatoes are often treated to prevent sprouting. For best results, buy certified disease-free slips from a garden supplier.
What if a late frost is forcasted after I plant?
Be prepared to cover your newly planted slips with row cover, cloches, or even old blankets if an unexpected cold night is predicted. It’s a common Tennessee spring challenge.
Can I grow sweet potatoes in containers?
Yes! Use a large container (20-gallon or bigger) with excellent drainage. Plant 1-2 slips per pot and ensure it gets plenty of sun. This is a great option for smaller spaces.
How long do sweet potatoes take to grow?
Most varieties need 90 to 120 frost-free days from planting to reach full maturity. That’s why hitting that May to early June planting window is so important in Tennessee.
By following these guidelines for when to plant sweet potatoes in Tennessee, you’ll give your garden the best chance for a productive and flavorful harvest. With a little patience at the start to wait for warm soil, you’ll be rewarded with a bounty that stores well and tastes of your own summer’s effort.