Plants in the Weather Records

Jefferson regularly experimented with new trees and crops and with new cultivars of familiar produce. The Garden Book includes 330 varieties of 99 plants over 50 years of records kept at Monticello. Species native to the Americas like the spicebush, the North American azalea, redbud trees, corn, and okra grew alongside European artichokes and guelder-roses, Asian paper mulberry and mimosa trees, and African black-eyed peas. Jefferson requested and received seed and root stock from correspondents in the states and around the globe. Philip Mazzei kept up a regular exchange of plants with Jefferson, Samuel Mitchill forwarded “a few Squash & Melon seeds just arrived from Lima,” and Thomas Appleton sent Maltese cotton and clover seed. From the nursery of William Prince in Flushing, New York, Jefferson ordered seed for the native sugar maple, hoping they promised “us an abundant supply of sugar at home.” Unfortunately, repeated plantings at Monticello failed to produce a sugar bush. Writing to Samuel Vaughan, Jefferson declared, “I have always thought that if in the experiments to introduce or to communicate new plants, one species in an hundred is found useful and succeeds, the ninety nine found otherwise are more than paid for.”

Jefferson’s own weather records contain over 150 notes on “the flowering, leafing, fruiting, falling of different kinds of trees & other vegetables.” In addition, he drew up a chart depicting the seasonal availability of 37 fruits and vegetables in the Washington, D.C., markets during his two terms as president of the United States. This graphic visualization of the arrival and departure of greens, raspberries, peaches, turnips, potatoes, and other fruits and vegetables from 1801 to 1809 gives us insight into what produce may have been served at the President’s House at a particular time of year. Jefferson’s recordkeeping in regard to crops and produce served him not only as a measure of the climate, but also as a way of keeping track of the species that most reliably provided plentiful and long-lasting harvests. In a time of truly seasonal eating, the plants that produced a large quantity over a long period were valued over those that were unreliable due either to their vulnerability to weather or to their natural tendency to produce smaller amounts. Finding varieties that bloomed earlier and lasted longer increased the amount of time they could be enjoyed at the table and the amount available to preserve. Jefferson asserted that “the greatest service which can be rendered any country is to add an useful plant to it’s culture,” an idea he returned to in letters expressing gratitude for the donation of seeds or plant stock to America.

Fruits and Vegetables

Jefferson’s notes on the leafing of trees, ripening of produce, the arrival of peas at the table, and the first killing frost in the fall round out the weather data to create a fuller account of local climates. He believed that the nature of the U.S. climate was “discoverable from the Thermometer, from the force and direction of the winds, the quantity of rain, the plants which grow without shelter in the winter &c.” In a letter to his daughter Maria, 9 March 1791, Jefferson expressed the hope that she would “note every appearance animal and vegetable which indicates the approach of Spring, and will communicate them to me. By these means we shall be able to compare the climates of Philadelphia and Monticello.” He encouraged his correspondents to share their observations with him, requesting phenological information from James Madison, Thomas Mann Randolph, and Giovannini Fabbroni, and directed Meriwether Lewis to make note of the leafing and flowering of plants on the western expedition. Among the categories of data Jefferson advised Madison to note in his daily weather record were the “shooting or falling of the leaves of trees, of flours, and other remarkeable plants.”


Edwin Morris Betts, ed., Thomas Jefferson’s Garden Book, 1766-1824 (Philadelphia, 1944).

Jefferson to Giovanni Fabbroni, 8 June 1778.

Jefferson to James Madison, 16 March 1784.

Jefferson to William Drayton, 30 July 1787.

Jefferson to Thomas Mann Randolph, Jr., 18 April 1790.

Jefferson to Samuel Vaughan, Jr., 27 November 1790.

Jefferson to Mary Jefferson, 9 March 1791.

Jefferson to William Prince, 6 July 1791.

Jefferson to Thomas Mann Randolph, 23 March [1797].

Summary of Public Service, [after 2 Sep. 1800].

Instructions for Meriwether Lewis, 20 June 1803

Philip Mazzei to Jefferson, 28 December 1803.

Philip Mazzei to Jefferson, 27 January 1804.

Jefferson to Nicholas King, 21 April 1805.

Jefferson’s Analysis of Weather Memorandum Book, January 1817.

Samuel L. Mitchill to Jefferson, 21 May 1819.

Thomas Appleton to Jefferson, 23 August 1819.


Garden vegetables Jefferson observed.

Interactive Visualizations

Explore some of the interactive visualizations created from Jefferson's observations.