The garden has high brick walls which trap heat, giving it a warm micro-climate, and it claims the largest fruiting olive tree in Britain and the world's northernmost grapefruit growing outdoors.

[2] Jealously guarded during the tenure of the Worshipful Society of Apothecaries, the garden became a registered charity[3] in 1983 and was opened to the general public for the first time.

Its seed-exchange programme was established following a visit in 1682 from Paul Hermann, a Dutch botanist connected with the Hortus Botanicus Leiden and has lasted until the present day.

The seed exchange programme's most notable act may have been the introduction of cotton into the colony of Georgia and more recently, the worldwide spread of the Madagascar periwinkle (Catharanthus roseus).

[citation needed] Isaac Rand, a member and a fellow of the Royal Society, published a condensed catalogue of the garden in 1730, Index plantarum officinalium, quas ad materiae medicae scientiam promovendam, in horto Chelseiano.