APL Cultivation is the title used for the series of 90-minute live chat lessons given by Adám Brudzewsky in the APL Orchard chat room. The name was first used for lesson 15 at the end of January 2018, but was since applied retroactively to all such lessons.
The first season consisted of 29 weekly sessions running from 18 October 2017 until 16 May 2018, covering most aspects of basic APL programming. A new series began on 28 November 201, with more in-depth lessons every two-three weeks.
Initially, the lessons were not organised, but were given completely impromptu. However, between lessons 2 and 3, Erik Konstantopoulos bookmarked the first two lessons using Stack Exchange's chat conversation bookmarking feature, and thus established the lessons as a numbered series.