Gerard's Herball drawings of plants and the printer's woodcuts are mainly derived from Continental European sources, but there is an original title page with a copperplate engraving by William Rogers.

[3] He was made an examiner of candidates for admission to the freedom of the company on 15 January 1598 and Junior Warden in August 1597, under the mastership of George Baker.

[6] While studying he developed the tenement garden in the suburb of Holborn, London, which he refers to frequently in his work, and later published a catalogue of the flowers there.

He surrounded himself with influential friends and contacts, including Lancelot Browne, George Baker, and the apothecaries James Garrett, Hugh Morgan and Richard Garth.

Garth, who described Gerard as "a worshipful gentleman and one that greatly delighteth in strange plants" had South American contacts from where he would import rarities.

He also exchanged plants with Clusius and cultivated a certain "Captain Nicholas Cleet of the Turky Company" from whom he obtained specimens from the Middle East.

George Baker describes the garden in his preface to the Herball as "all manner of strange trees, herbes, rootes, plants, floures and other such rare things, that it would make a man wonder, how one of his degree, not having the purse of a number, could ever accomplish the same".

[2] The publisher and Queen's Printer John Norton proposed to Gerard an English translation of Dodoens' popular herbal, Stirpium historiae pemptades sex (1583).

Gerard was not Norton's first choice, the translation having originally been commissioned from Dr Robert Priest,[c][18][19][20][21] a member of the London College of Physicians,[8][22] who had meanwhile died.

[26] In the preface ("To the courteous and well-willing Readers"), Gerard acknowledged Priest's efforts, but claimed the work was his own; "and since that Doctor Priest, one of our London Colledge, hath (as I heard) translated the last edition of Dodonaeus, which meant to publish the same; but being prevented by death, his translation likewise perished: lastly, my selfe one of the least among many, have presumed to set foorth unto the view of the world, the first fruits of these mine own labours"[27]This led to Gerard being accused of plagiarism, and even of being a "crook".

Gerard's lack of scientific training and knowledge led him to frequent inclusion of material that was incorrect, folkloric or mythical, such as the barnacle tree that bore geese (see illustration).

It hired L'Obel as an internationally recognised expert on plants, who as Gerard's friend had unwittingly contributed to his book, to proof the translations, fix the mismatched illustrations and right the textual wrongs.

Although Gerard was an experienced collector and plantsman, he lacked L'Obel's scholarship, as is clear in his dedication to Burghley, where he presents himself as a gardener.

[39] Gerard may be seen as one of the founders of botany in the English language, despite being ill-educated was more interested as a herbalist and barber-surgeon in the medicinal properties of plants than in botanical theory.

[9] His botanical shortcomings were ascribed by critics in his own time,[40] including John Ray, who commented that despite the fact that the book was the standard botany text in the 17th century, it was by an ignorant man whose lack of foreign languages meant he could not have translated the work.

[26] Because it was a practical and useful book, packed with helpful drawings of plants, and because Gerard had a fluid and lively writing manner, his Herball was popular with ordinary literate people in 17th-century England.

Although scholars at the time recognised that it was a pirated work with many limitations,[26] there is evidence of the book remaining in practical use as a medicinal herbal even in the early 19th century.

For example, the herb which produces the deathlike sleep of Juliet or Cymbeline may refer to nightshade, Mandragora or Doronicum, all listed and described in the Herball.

[42] The writer Mark Griffiths has claimed that the drawing of a man on the title page of the Herball depicts Shakespeare, but other scholars dispute this.

The earliest printed works in Renaissance natural history fell into two categories: 1. newly recovered, translated and corrected editions of ancient texts, and 2. herbals based on empirical knowledge of early botanists.

Although Francis Bacon advocated inductive thinking based on observation or description (empiricism) as the way to understand and report on the natural world, the early Renaissance printed herbals were slightly modified adaptations of works by their medieval predecessors.

These somewhat unscientific early scientists generally contented themselves with listing plants and occasionally other things like animals and minerals and noting their medical uses.