Zone 4 · Root Vegetables Growing Guide

When to Plant Sweet Potato
in Zone 4

Tropical vine that needs a long hot summer. Plant slips (rooted cuttings), not seeds. Incredibly productive in hot climates — one plant can yield 4–6 large sweet potatoes.

Plant outdoors
Jun 1 – Jun 15
Start indoors
Direct sow
Last Frost
~May 1
Days to harvest
90–120 days
Difficulty
Medium
Wrong season — Zone 4
Harvest window: Sep – Oct

Planting Calendar

In Zone 4, Sweet Potato should be planted outdoors Jun 1 – Jun 15, after the average last frost date of approximately May 1.

Marginal zone. Use slips and black plastic mulch. Choose 90-day varieties like Beauregard.

Care Guide

Sunlight
Full sun · 6–8 hrs/day
Watering
Moderate
Spacing
12–18 inches
Soil
Sandy, well-draining, loose
Days to maturity
90–120 days
Soil pH
5.5–6.5
plant tip · Zone 4

Marginal zone. Use slips and black plastic mulch. Choose 90-day varieties like Beauregard.

Feeding Schedule

How often
once at planting
Feed type
low nitrogen
Key timing
at planting only

Too much nitrogen produces lush vines at the expense of tubers. Minimal feeding is best — rich soil at planting is enough.

Companion Planting for Sweet Potato

What you plant next to sweet potato makes a real difference — some plants actively help, others compete or attract pests.

Grows well with
  • Beans
  • Burdock
Keep away from
  • Squash
  • Tomatoes
  • Sunflowers

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Common questions

In Zone 4, direct sow sweet potato outdoors Jun 1 – Jun 15 after your last frost date of approximately May 1. Marginal zone. Use slips and black plastic mulch. Choose 90-day varieties like Beauregard.
Zone 4 has an average last spring frost of approximately May 1 and a first fall frost around Oct 1. These dates vary by specific location — use your ZIP code in the plant app for precision based on the nearest NOAA weather station.
Good companion crops for sweet potato include Beans, Burdock. Avoid planting near Squash, Tomatoes, Sunflowers, which can compete for nutrients or attract pests.
Sweet Potato typically takes 90–120 days from transplant or direct sow to harvest in Zone 4. Expected harvest window: Sep – Oct.

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Sweet Potato in other zones
Crop Guides