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Academic field-trial guide · Moncada · Valencia

Growing sweet potatoes in Moncada · Valencia

An IVIA experiment at Moncada compared sweet potato planting on 19 May, 17 June and 11 July. In that 2005 trial, marketable yield and root size were strongest in the May planting and declined with delay.

Valencian Community · IVIA trial location

Growing for a home garden? See the general sweet potato guide.

Sweet potato field rows prepared for planting

Regional crop context

Sweet potatoes in Moncada · Valencia

The Ministry-hosted field study compared cultivars, planting dates, commercial yield and root size at a named Valencia research site.

These are cultivar-specific experimental dates from 2005, published in 2006. They describe the Moncada trial, not every Spanish climate or current grower practice.

Step 1 of 7 · Assess

Check the field and production system before ordering slips

Use the trial to compare cultivar and planting-date trade-offs. Confirm market specifications, slips, irrigation and harvest capacity before selecting the field date.

6 topics still to verify· planning aid only, not a suitability score

Local crop-planning checks

Walk low spots after rain. Confirm the bedder can make stable rows and that water can leave the field.

Not reviewed

Check previous sweet potato, grass or pasture history, nematode results, wireworm pressure and known disease patches.

Not reviewed

Confirm variety, slip quantity, delivery date, setter capacity, water at planting and a plan for keeping slips shaded before setting.

Not reviewed

Match variety and expected root size to the buyer’s fresh-market or processing specification, delivery timing and grading equipment.

Not reviewed

Confirm curing-room volume, airflow, pallet-bin handling and storage space before planting the acreage.

Not reviewed

Map the crop sequence and equipment-cleaning route so infested soil and plant material do not move between fields.

Not reviewed

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Need a field-specific review? Run a coordinate-level farm audit for localized conditions.

Read the field history before selecting slips

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

Choose a transplant window in Moncada · Valencia

The trial dates were 19 May, 17 June and 11 July. The month strip shows the Moncada reference point’s 1996–2025 climate means.

Early trial planting

19 May · trial date

The earliest tested date produced the strongest commercial yield and root-size results in the Moncada experiment.

Main trial planting

17 June · trial date

The June treatment had lower commercial yield and root size than May; results varied by cultivar.

Late trial planting

11 July · trial date

The July treatment was slightly below June overall, although one early cultivar performed better under the late date.

Early plantingMain plantingLate planting

Historical regional climate

Monthly soil and air temperature context

1996-01-01 to 2025-12-31

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

April 06

10th percentile

Median soil-warming date

April 25

median year

Late soil-warming date

May 09

90th percentile

  • Early · 10th percentile
  • Main · median
  • Late · 90th percentile
  • 77–86°F root range
  • Cooler or warmer than the root range

June: regional monthly means

Modeled soil temperature
26.0°C · 0–7 cm model layer
Mean air temperature
23.6°C

Months whose historical mean soil temperature reaches the 65°F reference: May, June, July, August, September, October. Months in the 77–86°F root-development range: June, July, August. 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 39.55°N, 0.40°W. 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.

Set the field date from a real soil 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.

Match the date to variety maturity

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

Build an aerated bed and keep the crop sequence clean

The study gives a 1.1 × 0.4 m trial layout. Prepare a loose, drained root zone and align the bed with the farm’s irrigation, planting and digging equipment.

The bed does several jobs

  • Improves aeration and drainage around developing roots.
  • Warms the crop zone for a warm-season transplant.
  • Gives the setter and digger a consistent row to follow.

Keep bed height and shape consistent with soil texture, water movement and the equipment used on the farm.

Cross-section of a crowned sweet potato bed with arrows showing surface runoff moving down the shoulders.
A crowned, loose bed gives developing roots an aerated zone and can shed surface water down its shoulders. Shape the row for field soil, drainage and equipment; schematic, not to scale.

Set fertility from the field test

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

Plant slips, not seed, and calculate the stand

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.

Sweet potato slip set diagonally with its shoot and leaves above the soil, at least three buried nodes, new roots and a 3–4 inch depth mark.
Set the slip so at least three nodes sit below the soil while the growing tip and leaves remain above. The 3–4 inch (7.6–10.2 cm) depth is a practical guide; node position is the key. Leaf shape varies by cultivar. Water after transplanting.

Regional starting pattern

Between rows
110 cm · trial pattern
Within row
40 cm · trial pattern
Transplant depth
3–4 in (7.6–10.2 cm), with at least three nodes covered

The Moncada study used 110 cm between rows and 40 cm between plants. The calculator defaults to that tested pattern and bounds planning changes.

Planting calculator

Estimate slips for your field

Spacing-based count

Estimated slips

22,727

at 110 × 40 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

Protect the establishment period and the root grade

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.

Get water onto the slip at planting

Water immediately after setting and maintain enough moisture for root establishment. Track rainfall and soil moisture; avoid keeping beds saturated.

Keep the field clean while the crop closes rows

Scout early and maintain a weed-free start through canopy closure. Choose current control methods for the farm’s production system.

Scout below the canopy as well

Wireworms, flea beetles and root-knot nematodes can downgrade roots. Keep field history and scouting records tied to each harvest lot.

Keep tools and planting stock clean

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

Dig at the planned size, cure quickly and protect the skin

The trial measured commercial yield and root size across the tested dates and varieties. Use cultivar maturity and target grade to set harvest.

A tractor lifting sweet potatoes during field harvest
At harvest, protect the skin and move roots promptly to curing; equipment and handling systems vary by region.

Harvest period

Use cultivar maturity and trial planting date to plan harvest

Plan by variety, market size, planting date, field condition and frost risk.

Cure

80–85°F · 85–90% RH

A crop-level curing reference is 7–10 days with airflow; use the facility and buyer protocol for the harvested lot.

Store

55–60°F · about 85% RH

Maintain stable temperature, humidity and ventilation after curing.

Step 7 of 7 · Reference

Evidence behind the Moncada · Valencia guide

View references (5)
  1. 1. MAPA / IVIA — Fechas de plantación de boniatoPublished 2006; field experiment in 2005

    Moncada planting dates of 19 May, 17 June and 11 July; commercial yield and root-size outcomes by cultivar; 1.1 × 0.4 m trial spacing.

  2. 2. Szarvas et al. — The effect of plant density on the yield of sweet potatoPublished 23 May 2019; three field seasons in southeast Hungary

    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.

  3. 3. Washington State University Extension — Sweetpotato Production PracticesPublished January 2026

    Crop-level soil-temperature context, bed preparation, equipment-led row spacing and the relationship between plant density and root size.

  4. 4. University of Missouri Extension — Growing Sweet PotatoesReviewed March 2026; originally published September 2017

    Crop-level transplant establishment, slips, frost sensitivity and raised-bed practice. Missouri calendar dates are not applied to other regions.

  5. 5. Texas A&M AgriLife — Sweet Potato commercial crop profileOlder technical profile; undated PDF

    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.

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