Where do these planting months come from?

Each range is a stored planting window for this crop and climate. A month that is not listed has no stored window. It is not a recommendation to skip planting.

Why can the same season appear more than once?

When two sources give different months for the same season, both ranges are listed. They are not averaged, and the gap between them is not filled in.

How are grower notes different from official windows?

Farmer field notes are labelled Farmer field experience, with the month they were noted. They are not official department windows, and they are not yet verified against official sources.

When to plant Tomato in Colombo

When to plant Tomato in Colombo. Stored windows: March; August. Ranges from different sources are not averaged.

Unverified — based on HORDI Crop - Tomato, Department of Agriculture Sri Lanka, accessed 2026-10-20: https://doa.gov.lk/hordi-crop-tomato/; confirm for your microclimate.

Stored planting windows

March
Transplant
Farmer field experience. Using 75–90 stored days. Plant in Mar, first harvest about 75–90 days later (around May–June). Calculated from the stored day count and the planting month. It is not a separate harvest calendar.
HORDI says the suitable nursery period is the middle of March. The grid marks all of March because a month is the finest step. The same page gives an optimum elevation of 1000-2000 m and also says the crop can be grown in almost all agroclimatic zones except the up-country wet zone. Colombo is not named.
Unverified — based on HORDI Crop - Tomato, Department of Agriculture Sri Lanka, accessed 2026-10-20: https://doa.gov.lk/hordi-crop-tomato/; confirm for your microclimate.
August
Transplant
Farmer field experience. Using 75–90 stored days. Plant in Aug, first harvest about 75–90 days later (around October–November). Calculated from the stored day count and the planting month. It is not a separate harvest calendar.
HORDI says the suitable nursery period is the end of August. The grid marks all of August. Transplanting is 14-18 days after sowing. No maturity day-count is stated.
Unverified — based on HORDI Crop - Tomato, Department of Agriculture Sri Lanka, accessed 2026-10-20: https://doa.gov.lk/hordi-crop-tomato/; confirm for your microclimate.

Season ranges

Two or more season ranges are stored. They are not joined. A month is marked only when it falls inside a stored range.

Yala is stored from more than one source, and the months do not match. Yala (FAO) is Mar–Aug. Yala (National Drought Plan) is Apr–Sep. Both ranges are shown. They are not averaged.
Maha is stored from more than one source, and the months do not match. Maha (FAO) is Sep–Feb. Maha (National Drought Plan) is Oct–Mar. Both ranges are shown. They are not averaged.

Rainfall seasons

First inter-monsoon: Mar–Apr (Rainfall)
Climate of Sri Lanka, Department of Meteorology, accessed 2026-10-20: https://meteo.gov.lk/index.php?option=com_content&view=article&id=94&Itemid=310&lang=en
Southwest monsoon: May–Sep (Rainfall)
Climate of Sri Lanka, Department of Meteorology, accessed 2026-10-20: https://meteo.gov.lk/index.php?option=com_content&view=article&id=94&Itemid=310&lang=en
Second inter-monsoon: Oct–Nov (Rainfall)
Climate of Sri Lanka, Department of Meteorology, accessed 2026-10-20: https://meteo.gov.lk/index.php?option=com_content&view=article&id=94&Itemid=310&lang=en
Northeast monsoon: Dec–Feb (Rainfall)
Climate of Sri Lanka, Department of Meteorology, accessed 2026-10-20: https://meteo.gov.lk/index.php?option=com_content&view=article&id=94&Itemid=310&lang=en

Agricultural seasons

Yala (FAO): Mar–Aug (Agricultural)
Improvement of plant nutrient management for better farmer livelihood, food security and environment in Sri Lanka, J.D.H. Wijewardena, Department of Agriculture, hosted by FAO, accessed 2026-10-20: https://www.fao.org/4/ag120e/AG120E12.htm
Maha (FAO): Sep–Feb (Agricultural)
Improvement of plant nutrient management for better farmer livelihood, food security and environment in Sri Lanka, J.D.H. Wijewardena, Department of Agriculture, hosted by FAO, accessed 2026-10-20: https://www.fao.org/4/ag120e/AG120E12.htm
Yala (National Drought Plan): Apr–Sep (Agricultural)
National Drought Plan for Sri Lanka, Ministry of Environment, September 2020, accessed 2026-10-20: https://www.unccd.int/sites/default/files/country_profile_documents/NDP%20of%20Sri%20Lanka-Final%20Report-Sept%202020.pdf
Maha (National Drought Plan): Oct–Mar (Agricultural)
National Drought Plan for Sri Lanka, Ministry of Environment, September 2020, accessed 2026-10-20: https://www.unccd.int/sites/default/files/country_profile_documents/NDP%20of%20Sri%20Lanka-Final%20Report-Sept%202020.pdf

Jan

Northeast monsoon, Maha (sources disagree)

Feb

Northeast monsoon, Maha (sources disagree)

Mar

First inter-monsoon, Yala (FAO), Maha (National Drought Plan)

Apr

First inter-monsoon, Yala (sources disagree)

May

Southwest monsoon, Yala (sources disagree)

Jun

Southwest monsoon, Yala (sources disagree)

Jul

Southwest monsoon, Yala (sources disagree)

Aug

Southwest monsoon, Yala (sources disagree)

Sep

Southwest monsoon, Maha (FAO), Yala (National Drought Plan)

Oct

Second inter-monsoon, Maha (sources disagree)

Nov

Second inter-monsoon, Maha (sources disagree)

Dec

Northeast monsoon, Maha (sources disagree)

Methodology

Where do these planting months come from?: Each range is a stored planting window for this crop and climate. A month that is not listed has no stored window. It is not a recommendation to skip planting.
Why can the same season appear more than once?: When two sources give different months for the same season, both ranges are listed. They are not averaged, and the gap between them is not filled in.
How are grower notes different from official windows?: Farmer field notes are labelled Farmer field experience, with the month they were noted. They are not official department windows, and they are not yet verified against official sources.

Tomato crop page · Planting calendar for Tomato in Colombo