Harmony Grove, an early botanic garden in Chester County, Pennsylvania, was originated by John Jackson and maintained by successive generations of his family.
- “I herewith send they brush by the bearer, Caleb Harland, being the first opportunity. Mind not the cost until I see thee. I have this request to make, if thou pleases; to save me some seed ot he Geranium, when ripe: also if thou couldst procure me a set or two of Rosemary, I should accept it as a favour, having lost mine the hard winter, and not got any since. Perhaps some slips set in the ground in season, would take root, and be safely moved towards fall.
- “I hope the public peace will add fresh life and vigour to every useful science that may tend to adorn and enrich our country: the propagation of plants being one, and much my delight. I take every help that I receive this way as a kindness."
- The Village Record newspaper (West Chester, Pa.), January 16, 1822, biographical account of John Jackson 
- "JOHN JACKSON, whose death was published in the last Record, was a native of Londongrove and was born where he died; his father was also born and died on the same plantation. His great grandfather was one of the earliest settlers in that neighborhood. There is something very pleasant in the idea, as it shows the general course of happiness and contentment that must have prevailed, to see the son succeeding to the father, generation after generation to the same farm; in eating the fruits planted by a father's hand; In planting fruits with the expectation that they shall be enjoyed by our children, many tender and pleasing recollections and anticipations arise. The object of this notice was one who never courted the public gaze; nor was he ambitious of public business or honor; not that he thought it improper. He held in respect those who preferred public service, but his genius led him another way. A self taught botanist, he took delight in cultivating in his leisure hours a garden, which he stocked with a multitude of indigenous and foreign fruits and flowers. The taste grew with his years, and there are few who have not seen and admired or heard of and wished to see, the garden of JOHN JACKSON. At this time it has a greater variety of rare trees, plants, fruits and flowers than the celebrated garden of Humphrey Marshall ever had. The orange and lemon trees are now bending with their golden honors; and as if in pride, yet blossoming for more. He was always an industrious man & in his latter years spent most of his time in his garden."
- Anonymous, 1828, account of the botanical and horticultural activities of John and William Jackson ("Chester County Cabinet of Natural Science," 1828: 303
- "The next garden in botanical importance [after that of Humphry Marshall] is that founded by the late John Jackson, in the township of London-Grove. Mr. Jackson was a member of the Society of Friends: he was an excellent gardener, and a highly respectable botanist. He was born in London-Grove, the 9th of November, 1748, and died in the same township, the 20th of December, 1821. The garden was commenced in the year 1776 or 1777: it contains about an acre and a half of ground, and is located in a lime-stone valley of extraordinary beauty and fertility. A small green-house is attached to the place: a spring yielding an abundant supply of water, takes its rise near the centre of the garden, and affords an opportunity for the growth of aquatic plants, and some others, which delight in a humid soil. The place presents a numerous collection of foreign and indigenous plants of much interest to the student of botany. Mr. Jackson… also paid attention to mineralogy. His son, William Jackson, the present proprietor of the garden, inherits his father’s love for natural science, and employs himself in making gradual improvements in the establishment.
- Darlington, William, 1849, description of the botanical activities of John and William Jackson (1849: 22, 549-50)
- "The laudable example of HUMPHRY MARSHALL was not without its influence in the community where he resided. His friend and neighbour, the late estimable JOHN JACKSON, was endowed with a similar taste for the beauties of nature; and, in the year 1777, commenced a highly interesting collection of plants, at his residence in Londongrove, which is still preserved in good condition, by his son WILLIAM JACKSON, Esq....
- "JOHN JACKSON, of Londongrove Township, Chester County, was one of the very contemporaries of HUMPHREY MARSHALL, who sympathized cordially with his pursuits. He commenced a garden soon after that at Marshallton was established, and made a valuable collection of rare and ornamental plants; which is still preserved in good condition by his son, WILLIAM JACKSON, Esq. JOHN JACKSON, was a very successful cultivator of curious plants, a respectable botanist, and one of the most gentle and amiable men."
- "Deaths," The Village Record (January 16, 1822), posted by J. D. Thomas, http://www.accessible-archives.com/2012/12/the-pennsylvania-genealogical-catalogue-1822/#ixzz3r66Db4dt Accessed 11/10/2015
- "Chester County Cabinet of Natural Science," The Register of Pennsylvania, 1 (1828), view on Zotero