Minnesota’s short growing season means potatoes must go in as soon as the soil is workable in spring. Knowing exactly When To Plant Potatoes In Minnesota can make the difference between a hearty harvest and a disappointing yield. This guide walks you through everything you need to know, from soil temperature to frost dates.
Understanding Minnesota’s Growing Zones
Minnesota spans USDA hardiness zones 3a to 5a. Your specific location determines when the ground thaws and warms up enough for planting.
Northern Minnesota (zones 3a-3b) has a shorter window. Southern Minnesota (zones 4b-5a) can plant a bit earlier. Always check your local frost dates before putting seed potatoes in the ground.
Last Spring Frost Dates By Region
- Northern Minnesota: May 15 to June 1
- Central Minnesota: May 1 to May 15
- Southern Minnesota: April 20 to May 5
Potatoes can tolerate light frost, but hard freezes will kill the tops. If you plant too early, you risk losing the foliage to a late freeze.
When To Plant Potatoes In Minnesota
The ideal time to plant potatoes in Minnesota is 2 to 4 weeks before the last expected spring frost. For most of the state, this falls between mid-April and early May.
Soil temperature matters more than the calendar date. Potatoes need soil temperatures of at least 45°F (7°C) at planting depth. If the soil is too cold and wet, seed potatoes will rot before they sprout.
Soil Readiness Check
- Dig down 4 inches in your garden bed.
- Grab a handful of soil and squeeze it.
- If it crumbles easily, it’s ready. If it forms a muddy ball, wait a few days.
- Use a soil thermometer to confirm 45°F or warmer.
In southern Minnesota, you can often plant by April 15. Central Minnesota usually starts around April 25. Northern Minnesota may need to wait until May 5 or later.
What If You Miss The Window?
Don’t worry if spring gets away from you. You can still plant potatoes in early June for a fall harvest. Just choose early-maturing varieties that finish in 70 to 90 days.
Choosing The Right Potato Varieties
Not all potatoes perform well in Minnesota’s climate. You want varieties that mature quickly and resist common diseases.
Early Season Varieties (70-80 Days)
- Red Norland
- Yukon Gold
- Dark Red Norland
- Caribe
Mid Season Varieties (80-100 Days)
- Kennebec
- Russet Burbank
- German Butterball
- All Blue
Late Season Varieties (100-120 Days)
- Russet Norkotah
- Butte
- Purple Viking
For northern Minnesota, stick with early or mid-season varieties. Southern gardeners can experiment with late-season types if they have a long enough fall.
Preparing Seed Potatoes For Planting
Seed potatoes are small potatoes or pieces of larger potatoes grown specifically for planting. Grocery store potatoes may carry diseases and are often treated to prevent sprouting.
Cutting And Curing
- Buy certified disease-free seed potatoes from a garden center or online supplier.
- Cut large potatoes into pieces about 1.5 to 2 ounces each. Each piece should have at least one “eye” (sprout).
- Let cut pieces cure for 1 to 3 days in a cool, humid place. This allows the cut surfaces to form a protective callus.
- Small seed potatoes can be planted whole.
Chitting (Optional But Helpful)
Chitting means pre-sprouting your seed potatoes indoors before planting. It gives them a head start in cold soil.
- Place seed potatoes in an egg carton or shallow tray with the eyes facing up.
- Keep them in a bright, cool room (50-60°F) for 2 to 4 weeks.
- Plant when sprouts are about 1/2 to 1 inch long.
Chitting is especially useful in northern Minnesota where the growing season is short.
How To Plant Potatoes In Minnesota
Proper planting technique sets your potatoes up for success. Follow these steps for a strong start.
Step 1: Choose The Right Location
Potatoes need full sun (at least 6 hours daily) and well-drained soil. Avoid low spots where water pools after rain. Wet soil leads to rot and disease.
Step 2: Prepare The Soil
Loosen the soil to a depth of 8 to 10 inches. Remove rocks, clumps, and weeds. Mix in 2 to 4 inches of compost or well-rotted manure.
Potatoes prefer slightly acidic soil with a pH between 5.0 and 6.5. If your soil is too alkaline, potatoes are more susceptible to scab disease.
Step 3: Dig Trenches Or Holes
You have two main planting methods:
- Trench method: Dig a trench 4 to 6 inches deep. Place seed potatoes 12 inches apart. Cover with 3 to 4 inches of soil.
- Hill method: Dig individual holes 4 inches deep. Place one seed potato in each hole. Cover with soil.
Rows should be 2 to 3 feet apart to allow room for hilling later.
Step 4: Plant At The Right Depth
Plant seed potatoes 4 inches deep in heavy clay soil, or 6 inches deep in sandy soil. Deeper planting protects against late frosts and keeps tubers from turning green.
Step 5: Water Well After Planting
Give the soil a good soaking after planting. Then wait until the sprouts emerge before watering again. Overwatering before emergence can cause rot.
Caring For Your Potato Plants
Once your potatoes are in the ground, they need consistent care through the growing season.
Hilling (Mounding Soil)
When the plants are 6 to 8 inches tall, mound soil up around the stems. This prevents tubers from being exposed to sunlight, which turns them green and toxic.
- First hilling: When plants are 6-8 inches tall
- Second hilling: 2 to 3 weeks later
- Third hilling (if needed): After flowering
Each time, add 3 to 4 inches of soil around the base of the plants. Leave only the top few inches of leaves exposed.
Watering
Potatoes need about 1 to 2 inches of water per week. Consistent moisture is critical during tuber formation, which starts about 6 weeks after planting.
Uneven watering causes knobby or misshapen tubers. Use drip irrigation or soaker hoses to keep foliage dry and reduce disease risk.
Fertilizing
Potatoes are heavy feeders. Apply a balanced fertilizer (10-10-10) at planting time. Side-dress with additional fertilizer when plants are 6 inches tall and again when they flower.
Too much nitrogen produces lush foliage but small tubers. Stick with a balanced approach.
Pest And Disease Management
Common potato problems in Minnesota include:
- Colorado potato beetles: Hand pick adults and larvae. Use row covers for small plantings.
- Flea beetles: Apply diatomaceous earth or neem oil.
- Late blight: Avoid overhead watering. Remove infected plants immediately.
- Scab: Maintain soil pH below 6.5. Plant resistant varieties.
Rotate your potato patch each year to reduce soil-borne diseases. Don’t plant potatoes in the same spot for at least 3 years.
When To Harvest Potatoes In Minnesota
Harvest time depends on the variety and when you planted. Most potatoes are ready 70 to 120 days after planting.
New Potatoes (Early Harvest)
You can dig new potatoes about 2 weeks after the plants finish flowering. These are small, thin-skinned, and perfect for boiling.
Gently dig around the base of the plant and remove a few tubers. Leave the plant in place to continue growing.
Full Harvest
Wait until the vines turn yellow and die back. This signals that the tubers have reached full size and the skins have thickened.
- Stop watering 2 weeks before harvest to toughen the skins.
- Use a garden fork to gently lift the tubers from the soil.
- Let potatoes sit on the ground for a few hours to dry.
- Brush off loose soil, but don’t wash them until you’re ready to eat.
Harvest Timing By Region
- Northern Minnesota: Late August to mid-September
- Central Minnesota: Late August to early October
- Southern Minnesota: September to mid-October
Harvest before the first hard frost in fall. A light frost won’t hurt the tubers underground, but a hard freeze can damage them.
Storing Potatoes For Winter
Proper storage keeps your harvest fresh for months. Follow these steps for best results.
Curing
Cure potatoes for 10 to 14 days after harvest. This heals minor cuts and thickens the skins for longer storage.
- Keep at 50-60°F with high humidity (85-90%)
- Place in a dark, well-ventilated area
- Don’t wash before curing
Long-Term Storage
After curing, move potatoes to a cool, dark, humid location. Ideal conditions are 40-45°F with 80-90% humidity.
Good storage options include:
- A root cellar
- An unheated basement
- A garage that stays above freezing
- A cool closet
Check stored potatoes regularly and remove any that sprout or rot. One bad potato can spoil the whole batch.
Common Mistakes Minnesota Gardeners Make
Avoid these pitfalls for a better potato harvest.
Planting Too Early
Impatience leads to rot. Wait until soil reaches 45°F, even if the calendar says it’s time.
Planting Too Deep Or Too Shallow
Too deep and the sprouts struggle to emerge. Too shallow and tubers turn green. Stick with 4 to 6 inches.
Skipping Hilling
Hilling is not optional in Minnesota. Our short season means tubers form close to the surface. Hilling protects them from sun and frost.
Overwatering
Potatoes need moisture, but soggy soil causes rot. Water deeply but infrequently, especially in clay soils.
Ignoring Pest Problems
Colorado potato beetles can defoliate plants in days. Check your plants weekly and act fast if you see pests.
Frequently Asked Questions
Can I Plant Potatoes In Minnesota In July?
Yes, but only early-maturing varieties like Red Norland. You’ll harvest in late September or October before the ground freezes.
What Is The Best Potato Variety For Northern Minnesota?
Yukon Gold and Red Norland are reliable choices. They mature in 70-80 days and tolerate cool soil.
Do I Need To Fertilize Potatoes In Minnesota?
Yes. Potatoes are heavy feeders. Apply a balanced fertilizer at planting and again during the growing season.
How Deep Should I Plant Seed Potatoes In Clay Soil?
Plant 4 inches deep in heavy clay. Deeper planting in clay can cause rot because the soil stays wet longer.
Can I Grow Potatoes In Containers In Minnesota?
Absolutely. Use a 10-gallon pot or grow bag. Fill with loose potting soil and follow the same planting and hilling steps.
Final Tips For Success
Planting potatoes in Minnesota is all about timing and preparation. Start with certified seed potatoes, wait for the right soil temperature, and hill your plants regularly.
Keep an eye on the weather. A late frost in May can damage young plants, so be ready to cover them with row covers or straw if needed.
With a little planning, you can enjoy fresh, homegrown potatoes from late summer through winter. The key is knowing exactly When To Plant Potatoes In Minnesota and following through with consistent care.
Happy gardening, and enjoy your harvest.