API & MCP

Everything a person can do on Sowing and Planting Calendar, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://hearthsowingcalendar.usefulweb.site/api/v1/calculate – run Sowing and Planting Calendar
GET https://hearthsowingcalendar.usefulweb.site/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Sowing and Planting Calendar

Turns your last spring and first autumn frost dates into a sowing and planting calendar for up to 40 vegetables and herbs: indoor sowing, planting out, sowing outside with successive sowings, autumn planting and the harvest window, plus a calendar file with every date.

Inputs of Sowing and Planting Calendar
Field	Type	Default	Description
`crops`	multiselect (tomato, pepper, eggplant, potato, cucumber, zucchini, squash, melon, sweetcorn, bush-bean, pole-bean, pea, broad-bean, lettuce, spinach, chard, beet, carrot, parsnip, radish, turnip, onio	["tomato","lettuce","carrot","bush-bean","garlic"]	Crops
`lastFrost` (required)	text	"04-20"	Last spring frost (MM-DD). Month and day, for example 04-20. The Frost Dates Finder gives it for Germany and the United States.
`firstFrost` (required)	text	"10-15"	First autumn frost (MM-DD)
`year`	integer	2027	Season (year of the spring frost)

Example request

Berlin, typical frost dates, five crops

curl -X POST https://hearthsowingcalendar.usefulweb.site/api/v1/calculate -H 'content-type: application/json' -d '{"crops":["tomato","lettuce","carrot","bush-bean","garlic"],"lastFrost":"04-08","firstFrost":"11-02","year":2027}'

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

Streamable HTTP endpoint: https://hearthsowingcalendar.usefulweb.site/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: hearth_sowing_calendar
Local stdio connector: node src/mcp-stdio.ts --tool=hearth-sowing-calendar

{
  "mcpServers": {
    "hearth-sowing-calendar": { "type": "http", "url": "https://hearthsowingcalendar.usefulweb.site/mcp" }
  }
}