Here is a list of oft-cited journals containing articles pertaining to school gardens.
Nature-Study Review
Nature-Study Review 1, 1905. [pdf: 288 pages]
Nature-Study Review 2, 1906. [pdf: 408 pages]
Nature-Study Review 3, 1907. [pdf: 296 pages]
Nature-Study Review 4, 1908. [pdf: 304 pages]
Nature-Study Review 5, 1909. [pdf: 262 pages]
Nature-Study Review 6, 1910. [pdf: 304 pages]
Nature-Study Review 7, 1911. [pdf: 352 pages]
Nature-Study Review 8, 1912. [pdf: 428 pages]
Nature-Study Review 9, 1913. [pdf: 332 pages]
Nature-Study Review 10, 1914. [pdf: 498 pages]
Nature-Study Review 11, 1915. [pdf: 460 pages]
Nature-Study Review 12, 1916. [pdf: 432 pages]
Nature-Study Review 13, 1917. [pdf: 434 pages]
Nature-Study Review 14, 1918. [pdf: 438 pages]
Nature-Study Review 15, 1919. [pdf: 392 pages]
Nature-Study Review 16, 1920. [pdf: 454 pages]
Nature-Study Review 17, 1921. [pdf: 442 pages]
Nature-Study Review 18, 1922. [pdf: 452 pages]
School Life
School Life: The Official organ [journal] of the United States Bureau of Education, Department of the Interior. 1918-1964, ISSN 1356-9463
This magazine has many articles pertaining to school gardens and the US School Garden Army.
Volumes 1-3, Volumes 4-6, and Volumes 7-9 are available full text online through Google Books. Later volumes are present but not fully accessible.
Putnam, Helen C. 1902. Native plants for the school garden. Education 22.9:561-564.
1,500,000 Enlist in School Farm Army; Government Tells of Big Results from the Work of Country's Boys and Girls.60,000 Arcres are tilled. Accounts for Last Year Show a Profit of More Than $5 for Every Dollar Expended. Hope for 5,000,000 Army. Show Large Profits. Oct 20, 1918. New York Times. p. 85 (1 page).
Alaskan Gardens. June 1918. The Playground 12.3:103.
Childs, Breta W. 1923. The Need for Gardening as an Intermediate Grade Subject in City Schools. Nature-Study Review 19: 79–82.
Garden Army officers and their value. June 1920. The Playground, 14.3:181-183.
Hinsdell, Arthur Bemis. April 1911. School gardens of Saginaw. American City 4:185-7.
Kolbe, Parke R. May 25, 1918. War Work of the Unites States Bureau of Education. School and Society 7.178:606-609.
Ling, Ping. June 1918. School Children and Food Production. The Pedagogical Seminary 25.2:163-190.
School Garden Exhibits; Seventy-Eight Have Gardens, an Increase of Seven Over Last Year. June 18, 1922. New York Times.
The Unites States Volunteer War-garden Army. March 23, 1918. School and Society 7.169:350-351.
MSU access is limited: Recreation. New York : National Recreation Association. Pub History: Vol. 24, no. 10 (Jan. 1931)-v. 58, no. 10 (Dec. 1965)
Kilpatrick, Van Evrie. Vegetables for victory. Recreation, 35 (March 1942): 743-744.
Kilpatrick, Van Evrie. Gardens for recreation. Recreation, 35 (January 1942): 620-621
Young, Paul R. School gardens yield invisible corps. Recreation, 31 (March 1938): 693-695, 734
Loomis, C. Frances. Learning in a garden. Recreation, 31 (March 1938): 696-698
Kersey, Vierling. Children garden and grow. Recreation, 31 (March 1938): 699-700
Shaw, Ellen Edddy. Children's garden work in a botanical garden. Recreation, 31 (March 1938): 691-692
Sullivan, Frederick R. Development of school gardening in Boston. Recreation, 31 (March 1938): 707-709
Davey, Mildred. Children's gardens as a community project. Recreation, 31 (March 1938): 710, 738-739
Bennett, Billie L. Enjoying nature - What does it mean? Recreation, 31 (May 1938): 78, 108, 110
Melchoir, Juanita McDouglad. Garden club as an educational factor in North Carolina schools. Recreation, 31 (March 1938): 711-714
Wellington, Marjorie. Garden Institute of Buffalo. Recreation, 31 (March 1938): 715-717, 739
Gridley, Abbie E. Gardening - A happy occupation for children. Recreation, 31 (May 1938): 67-69
Warren, Gertrude L. Gardening with 4-H clubs. Recreation, 31 (March 1938): 701-702, 734
Jones, Paul H. The Fordson Horticultural Gardens. Recreation, 31 (March 1938):727-728, 741
Welcome to the Battle Creek Public School Garden. Horticultural News, 10:3 (March 1944): 22-23.