Trial planting
16 May · 2019 trial dateThe state research trial transplanted on 16 May using treatment variants that included mulch film and protective covers.
State field-trial guide · Gülzow-Prüzen · Mecklenburg-Western Pomerania
Mecklenburg-Western Pomerania’s state research institute tested sweet potatoes at Gülzow-Prüzen, with the 2019 crop planted on 16 May and harvested in September. Marketable yield varied with treatment and pest damage.
State research station · Gülzow-Prüzen trial field
Growing for a home garden? See the general sweet potato guide.

Regional crop context
Repeated state field trials establish experimental growing potential at this site. The reports also document variable marketable yield, pest damage and misshapen roots, so trial success is not a commercial-profit guarantee.
The dates and climate point refer to the Gülzow-Prüzen trial field, not the whole state. The 2019 trial included soil-warming and protective treatments.
Step 1 of 7 · Assess
Treat Gülzow-Prüzen as experimental evidence. Before commercial acreage, assess pest history, marketable-root grading, slip quality, irrigation, and the availability of warming covers and harvest capacity.
6 topics still to verify· planning aid only, not a suitability score
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Need a field-specific review? Run a coordinate-level farm audit for localized conditions.
Root-knot nematodes, wireworms and other soilborne pests affect marketable roots. Soil sampling, clean planting material, crop rotation and equipment sanitation are the first decisions; chemical treatment depends on current field results and product labels.
Step 2 of 7 · Plan
The state trial recorded planting on 16 May. The month strip marks May as the trial month and pairs that evidence with 1996–2025 climate context at Gülzow-Prüzen.
The state research trial transplanted on 16 May using treatment variants that included mulch film and protective covers.
Historical regional climate
Green tiles are months whose mean soil temperature is in the 77–86°F root-development range; all other tiles are neutral and show the value. Early, main and late badges mark the 10th, median and 90th-percentile dates for reaching 18.3°C for 4 consecutive days. Bar height shows the mean.
Early soil-warming date
June 05
10th percentile
Median soil-warming date
June 23
median year
Late soil-warming date
July 15
90th percentile
Months whose historical mean soil temperature reaches the 65°F reference: July, August. Months in the 77–86°F root-development range: none in the available record. These are monthly regional averages, not planting dates or a frost check.
Open-Meteo · era5_land · 1996-01-01 to 2025-12-31 · Reference point 53.81°N, 12.11°E. Soil-temperature values are modeled at 0–7 cm model layer; the 65°F (18.3°C) transplant reference comes from a 4-inch field measurement. Use the regional calendar above with a current field reading.
Sweet potato slips establish best after frost risk has passed and the soil is at least 65°F (18.3°C) at 4 inches. That is a field measurement; the climate strip above shows regional history.
Use the regional crop duration and expected fall cutoff to choose a variety and harvest date. Confirm market grade, digging capacity and curing space before planting.
Step 3 of 7 · Prepare
The northern trial used raised beds or potato ridges, irrigation and soil-warming treatments. These methods affect the seed-zone climate and should be considered when comparing the trial to a bare-soil climate average.
Keep bed height and shape consistent with soil texture, water movement and the equipment used on the farm.

Base pH and fertilizer rates on representative soil tests. Avoid excess nitrogen, which can favor vine growth over marketable storage-root sizing.
Step 4 of 7 · Establish
Sweet potatoes are established from vegetative vine cuttings called slips. Buy clean, healthy slips in the target variety and quantity, and keep them shaded and moist until planting.

The northern German trial reports ridge/bed methods; the calculator uses the published European field-trial envelope of 80–100 × 20–30 cm as a crop-level starting point.
Planting calculator
Estimated slips
39,216
at 85 × 30 cm
Estimate = field area ÷ row-by-slip spacing. Keep values within the published bounds, then match the starting pattern to equipment and target root grade. Headlands and replant allowance are not included.
Step 5 of 7 · Manage
The first weeks determine how evenly slips establish and how the crop competes. Protect the crop from early weed competition and scout for wireworms, flea beetles and root-knot nematodes. Use field history, clean planting material and equipment sanitation to reduce avoidable risk.
Water immediately after setting and maintain enough moisture for root establishment. Track rainfall and soil moisture; avoid keeping beds saturated.
Scout early and maintain a weed-free start through canopy closure. Choose current control methods for the farm’s production system.
Wireworms, flea beetles and root-knot nematodes can downgrade roots. Keep field history and scouting records tied to each harvest lot.
Use certified or otherwise clean slips, avoid carrying soil on slips, and clean equipment after infested fields to limit movement of nematodes and soilborne disease.
Step 6 of 7 · Harvest
The 2019 trial harvested on 11 September after about 118 days. Plan for the tested maturity and inspect roots for pest injury before grading.

Harvest period
Plan by variety, market size, planting date, field condition and frost risk.
Cure
A crop-level curing reference is 7–10 days with airflow; use the facility and buyer protocol for the harvested lot.
Store
Maintain stable temperature, humidity and ventilation after curing.
Step 7 of 7 · Reference
Gülzow-Prüzen trial site, 16 May planting, warming treatments, 11 September harvest and marketability limitations.
European field trial comparing 80 × 20, 80 × 30, 100 × 20 and 100 × 30 cm row-by-plant spacing. Used as a crop-level spacing reference, not a local calendar.
Crop-level soil-temperature context, bed preparation, equipment-led row spacing and the relationship between plant density and root size.
Crop-level transplant establishment, slips, frost sensitivity and raised-bed practice. Missouri calendar dates are not applied to other regions.
Shared crop-level reference for curing and storage conditions. Its Texas planting calendar is used only on the Texas page.
Photo authorship and licence information are recorded centrally. View photo credits.