Clove Story

The research behind the guide

What field trials found about growing garlic, in plain numbers. The guide's steps come from extension services; these are the trial results worth knowing.

Planting date

In an Ontario trial with an average first frost of 13 October, plantings from 30 August to 5 October did about equally well, and many cloves planted after 27 October did not survive. It is one site, so the guide's planting windows follow extension services instead.

Ontario Ministry of Agriculture vegetable specialists, ONvegetables (Travis Cranmer), When is the best time to plant garlic? (January 30, 2024); Ontario Ministry of Agriculture vegetable specialists, ONvegetables (Travis Cranmer), When is the Best Time to Plant Garlic? (August 18, 2026); Colorado State University Extension, Tri River Area, Fall Planting: Garlic in Western Colorado (2025)

Spacing

Cloves set 6 inches apart made significantly more large bulbs than cloves set 3 inches apart. Closer spacing gives more bulbs, but smaller ones.

Colorado State University Specialty Crops Program, The Garlic Project 2004

Mulch

In a Colorado trial, mulched beds grew bigger bulbs than bare ground, while winter survival was about the same either way. On a different site, a trial found better survival under black plastic than on bare soil.

Colorado State University Specialty Crops Program, Garlic Winter Mulch Study, 2002 to 03; Walters, S.A. (2008), HortTechnology 18(2):286 to 289

Foliar feeding

Sprays of fish or kelp fertilizer during bulbing made no measurable difference in a Colorado trial.

Colorado State University Specialty Crops Program, Garlic Fertilization and Foliar Feeding, 2005

Water

In a wet year at 6-inch spacing, 13.3 inches of water from rain and drip did as well as 20.9 inches. The trial did not test going without water.

Colorado State University Specialty Crops Program, The Garlic Project 2004

Scapes

Over three years, removing scapes early gave a bigger total crop than leaving them on. Late removal also gave bigger bulbs, but did not raise the total crop significantly. On poor, sandy soil, removing curled scapes added 15 percent. On rich soil the gain was small. Removal didn't raise weight loss in storage.

Pelter et al. (2005), Acta Horticulturae 688:323 to 326; Guo et al. (2026), HortScience 61(6):1348 to 1357; Rosen & Tong (2001), HortScience 36(7):1235 to 1239; Colorado State University Specialty Crops Program, The Garlic Project 2004

Harvest timing

In an Ethiopian trial, waiting until all the tops had fallen gave the most garlic. Bulbs lifted when 80 percent of the tops had fallen, then cured, lost the least weight and sprouted least in storage. Most extension services judge harvest by green leaves instead, and warn that bulbs left too long split and store poorly.

Desta, Woldetsadik & Ali (2021), The Open Biotechnology Journal 15(1):36 to 45; University of Minnesota Extension, Growing garlic in home gardens; UMass Extension Vegetable Program (tips from Cornell Cooperative Extension), Garlic Harvest, Curing, and Storage; Montana State University Extension, Growing Garlic in Montana (MT199904AG); Iowa State University Extension and Outreach, Growing Garlic in the Home Garden; PlantTalk Colorado, Colorado State University Extension, 1827 Harvesting Garlic; University of Georgia Extension, Garlic Production for the Gardener (C854); Oregon State University Extension Service, Fall is the best time to plant garlic in Oregon (2023, reviewed 2025); Washington State University Extension, Vegetables: Growing Garlic in Home Gardens (FS162E)

White rot

No garlic variety tested resisted white rot, including one sold as resistant. Soil treatments that killed over 90 percent of the white rot in the soil still left heavy losses in the next garlic crop.

Coley-Smith & Entwistle (1988), Plant Pathology 37(2):261 to 264; Clarkson et al. (2006), Plant Pathology 55(3):375 to 386; Davis, Hao, Romberg, Nunez & Smith (2007), Plant Disease 91(2):204 to 208; Elshahawy, Morsy, Abd-El-Kareem & Saied (2019), Heliyon 5(1):e01168; Merriman, Isaacs, MacGregor & Towers (1980), Ann. Appl. Biol. 96(2):163 to 168

Hot water treatment for bloat nematode

Soaking seed cloves at 100°F for 30 to 60 minutes and then at 120°F for 15 to 30 minutes cut bloat nematode but did not clear it. Adding bleach to a 20 minute hot dip helped at 1.05 to 1.3 percent sodium hypochlorite. At 1.75 percent and above it injured cloves. Check the strength on the label. For 6 percent bleach, mix 1 part bleach with 4 parts water. For 7.5 to 8.25 percent, mix 1 part with 6 parts water.

Roberts & Matthews (1995), Journal of Nematology 27(4):448 to 456; Roberts & Greathead (1986), Journal of Nematology 18(1):66 to 73; Dugan, Hellier & Lupien (2007), Journal of Phytopathology 155(7 to 8):437 to 445

Rotation after bloat nematode

In a greenhouse test, bloat nematode taken from garlic did not reproduce on corn, soybean, barley, alfalfa, mustard or carrot. Extension services advise keeping onion-family crops out of an infested bed for about four years.

Poirier et al. (2019), Plant Disease 103(3):456 to 460; Marek et al. (2010), Plant Pathology 59(5):931 to 943; Mouttet et al. (2014), Pest Management Science 70(7):1017 to 1022; Cornell University, New York State Agricultural Experiment Station (June 2015), Bloat Nematode on Garlic; UMass Extension Vegetable Program, Garlic Bloat Nematode; New England Vegetable Management Guide, Garlic: Disease Control; University of Maine Cooperative Extension, Maine Garlic Pest Field Notebook; University of Minnesota Extension, What's wrong with my plant? Garlic: leaves yellow then wilt

Every source

Every variety value on this site is copied from that variety's own page at the supplier named beside it. Growing advice comes from university extension publications, checked a second time against the page cited. Trial results come from the papers listed here.

  1. Alabama Cooperative Extension System. Horticulture Notes: Add Garlic to Your Garden
  2. Ask Extension (eXtension Foundation), answered by an Extension expert. No garlic clusters only single bulbs
  3. Bloem, Haneklaus & Schnug (2011), J. Agric. Food Chem. 59(9):4442 to 4447
  4. Clarkson et al. (2006), Plant Pathology 55(3):375 to 386
  5. Clemson Cooperative Extension, Home & Garden Information Center. Onion, Leek, Shallot, & Garlic (HGIC 1314)
  6. Clemson University Cooperative Extension (copy hosted by UC ANR). Preserving Onions and Garlic
  7. Coley-Smith & Entwistle (1988), Plant Pathology 37(2):261 to 264
  8. Colorado State University Extension, El Paso County. Year Round Gardening: It's Time to Plant Garlic (2018)
  9. Colorado State University Extension, Tri River Area. Fall Planting: Garlic in Western Colorado (2025)
  10. Colorado State University Specialty Crops Program, Garlic Fertilization and Foliar Feeding, 2005
  11. Colorado State University Specialty Crops Program, Garlic Winter Mulch Study, 2002 to 03
  12. Colorado State University Specialty Crops Program, The Garlic Project 2004
  13. Conci et al. (2003), Plant Disease 87(12):1411 to 1415
  14. Conci, Canavelli & Balzarini (2010), Journal of Phytopathology 158(3):186 to 193
  15. Cornell AgriTech, Cornell University. Diseases of garlic (Frank Hay, NOFA Winter Conference 2019)
  16. Cornell Cooperative Extension, St. Lawrence County. Time to plant garlic!
  17. Cornell Plant Disease Diagnostic Clinic. Diseases of Garlic: Various Pests
  18. Cornell Small Farms Program (article by Petra Page-Mann of Fruition Seeds, a seed company; grower opinion). Six Mistakes to Avoid When Planting Garlic & Shallots (2019)
  19. Cornell University CALS, Horticulture Section (Steve Reiners). Plan on Garlic This Fall (2020)
  20. Cornell University, Long Island Horticultural Research and Extension Center. Garlic rust
  21. Cornell University, New York State Agricultural Experiment Station (June 2015). Bloat Nematode on Garlic
  22. Crowe, Hall, Greathead & Baghott (1980), Phytopathology 70:64 to 69
  23. Davis, Hao, Romberg, Nunez & Smith (2007), Plant Disease 91(2):204 to 208
  24. Desta, Tena, Amare & Ferrante (2021), The Scientific World Journal 2021:7351873
  25. Desta, Woldetsadik & Ali (2021), The Open Biotechnology Journal 15(1):36 to 45
  26. Dugan, Hellier & Lupien (2007), Journal of Phytopathology 155(7 to 8):437 to 445
  27. Elshahawy, Morsy, Abd-El-Kareem & Saied (2019), Heliyon 5(1):e01168
  28. Guo et al. (2026), HortScience 61(6):1348 to 1357
  29. HortScience abstract via phtnet.org. Low-temperature storage of garlic for spring planting (Volk, Rotindo and Lyons, HortScience 39:571 to 573, 2004), abstract
  30. Iowa State University Extension and Outreach. Growing Garlic in the Home Garden
  31. Iowa State University Extension and Outreach, Yard and Garden. When and where should I plant garlic?
  32. Iowa State University Extension, Yard and Garden. It's only February, but my garlic is coming up. What should I do?
  33. Iowa State University Extension, Yard and Garden. How to Calculate Fertilizer Rates for the Garden
  34. Iowa State University Extension, Yard and Garden. How do I grow and care for garlic?
  35. Johnny's Selected Seeds. Garlic growing guide (seed company, practical arrival point only)
  36. Liu et al. (2024), J. Agric. Food Chem. 72(17):10117 to 10126
  37. LSU AgCenter. Garlic in the Garden
  38. LSU AgCenter, Livingston Parish. Growing Garlic (2015)
  39. Marek et al. (2010), Plant Pathology 59(5):931 to 943
  40. Melo Filho et al. (2006), European Journal of Plant Pathology 116(2):95 to 101
  41. Merriman, Isaacs, MacGregor & Towers (1980), Ann. Appl. Biol. 96(2):163 to 168
  42. Montana State University Extension. Growing Garlic in Montana (MT199904AG)
  43. Montana State University Extension. Growing Garlic in Montana (MT199904AG)
  44. Mouttet et al. (2014), Pest Management Science 70(7):1017 to 1022
  45. NC State Extension, Lee County Center. Growing Garlic in the South (2022)
  46. NC State Extension, Pamlico County Center. Let's Plant Some Garlic
  47. NC State Extension, Pender County Center. Time to Plant Onions and Garlic
  48. New England Vegetable Management Guide. Garlic: Insect Control
  49. New England Vegetable Management Guide. Garlic: Disease Control
  50. New England Vegetable Management Guide. Garlic: Weed Control
  51. New England Vegetable Management Guide (New England land-grant extension). Garlic
  52. New Mexico State University Cooperative Extension. Garlic Production in New Mexico (Guide H-234)
  53. New Mexico State University Cooperative Extension. Garlic Production in New Mexico (Guide H-234)
  54. North Dakota State University Extension. Plant Garlic This Fall (2011 news release)
  55. North Dakota State University Extension (Carrie Knutson). Growing Great Garlic (slides)
  56. Ohio State University Extension. Growing Garlic in the Garden (HYG-1627)
  57. Ohio State University Extension (Ohioline). Growing Garlic in the Garden (HYG-1627)
  58. Ontario Ministry of Agriculture vegetable specialists, ONvegetables (Travis Cranmer). When is the Best Time to Plant Garlic? (August 18, 2026)
  59. Ontario Ministry of Agriculture vegetable specialists, ONvegetables (Travis Cranmer). When is the best time to plant garlic? (January 30, 2024)
  60. Oregon State University Department of Horticulture. Garlic (Oregon Vegetables commercial production guide)
  61. Oregon State University Extension. Garlic for the Home Garden (FS 138, archived and marked out of date)
  62. Oregon State University Extension Service. Fall is the best time to plant garlic in Oregon (2023, reviewed 2025)
  63. Oregon State University Extension Service. Fall is the best time to plant garlic in Oregon
  64. Oregon State University Extension Service, Food Hero. Garlic (Fall), Quick Garden Tips
  65. Pelter et al. (2005), Acta Horticulturae 688:323 to 326
  66. Penn State Extension. Growing and Using Garlic
  67. Penn State Extension. Growing Garlic: Fall Planting
  68. PlantTalk Colorado, Colorado State University Extension. 1827 Harvesting Garlic
  69. Poirier et al. (2019), Plant Disease 103(3):456 to 460
  70. Roberts & Greathead (1986), Journal of Nematology 18(1):66 to 73
  71. Roberts & Matthews (1995), Journal of Nematology 27(4):448 to 456
  72. Rosen & Tong (2001), HortScience 36(7):1235 to 1239
  73. Rutgers NJAES Cooperative Extension. FS1233: Growing Garlic in the Home Garden
  74. South Dakota State University Extension. Planting Garlic
  75. Sow True Seed. How Much Seed Garlic Do I Need? (seed company, practical sizing only)
  76. Texas A&M AgriLife Extension, Travis County. In Austin's October Vegetable Garden (2023)
  77. Texas AgriLife Extension Service. Garlic (production sheet), Dr. Joe Masabni
  78. Texas AgriLife Extension Service (Joe Masabni). Garlic (crop production sheet)
  79. The Scientific World Journal. Duration of Low-Temperature Storage, Clove Topping and Gibberellic Acid on Emergence, Yield and Yield Components of Garlic (Desta, Woldetsadik, Mohammed and Tena, 2022)
  80. UC Davis Vegetable Research and Information Center. Garlic (Home Vegetable Gardening)
  81. UC Marin Master Gardeners, UC ANR. Garlic (grow sheet)
  82. UC Master Gardener Program of Contra Costa, UC ANR. Garlic, Love It or Leave It (2024)
  83. UC Master Gardeners of Tulare and Kings Counties, UC Cooperative Extension. Grow Your Own Garlic 2020 (UC Master Gardener newspaper column)
  84. UC Statewide IPM Program. Rust: Onion and Garlic Pest Management Guidelines
  85. UC Statewide IPM Program. Thrips: Onion and Garlic Pest Management Guidelines
  86. UC Statewide IPM Program. White Rot (home and landscape)
  87. UC Statewide IPM Program. White Rot: Onion and Garlic Pest Management Guidelines
  88. UC Statewide IPM Program. Fusarium Basal Rot: Onion and Garlic Pest Management Guidelines
  89. UC Statewide IPM Program. Integrated Weed Management, Onion and Garlic (Pest Management Guidelines)
  90. UC Statewide IPM Program. Cultural Tips for Growing Onions and Garlic
  91. UC Statewide IPM Program (UC ANR). Cultural Tips for Growing Onions and Garlic
  92. UCCE Master Gardeners of Tuolumne and Calaveras Counties, UC ANR. Planting Garlic (Wendy Kubow)
  93. UConn Extension. Garlic Cultivation in Connecticut
  94. UF/IFAS Extension Pasco County. Growing Garlic in Florida (2026)
  95. UF/IFAS Extension, Horticultural Sciences Department. Garlic, Allium sativum L. (HS597). Copy hosted by growables.com; the EDIS page no longer resolves
  96. UF/IFAS Gardening Solutions. Garlic
  97. UMass Amherst Center for Agriculture, Food, and the Environment (Home Lawn and Garden). Growing Garlic: Getting Started
  98. UMass Extension Center for Agriculture with University of Maine Cooperative Extension. Growing Garlic
  99. UMass Extension Vegetable Program. Alliums, White Rot
  100. UMass Extension Vegetable Program. Garlic Bloat Nematode
  101. UMass Extension Vegetable Program (tips from Cornell Cooperative Extension). Garlic Harvest, Curing, and Storage
  102. UNH Cooperative Extension. Growing Garlic in New Hampshire
  103. UNH Cooperative Extension. Growing Garlic in New Hampshire
  104. Universidade Estadual de Maringa (peer-reviewed journal). Periods of weed interference in garlic crop (Guerra et al. 2024), Acta Scientiarum Agronomy 46:e68403
  105. University of Arizona Cooperative Extension, Yavapai County. Backyard Gardener #160: Garlic (2024)
  106. University of Arkansas Division of Agriculture Cooperative Extension. Home Gardening Series: Garlic (FSA6085)
  107. University of California Agriculture and Natural Resources. Garlic: Safe Methods to Store, Preserve, and Enjoy (ANR Publication 8568)
  108. University of California ANR. Garlic: Safe Methods to Store, Preserve, and Enjoy (ANR Publication 8568)
  109. University of Georgia Cooperative Extension. Production and Management of Garlic, Elephant Garlic, and Leek (Circular 852)
  110. University of Georgia Extension. Garlic Production for the Gardener (C854)
  111. University of Idaho Extension. Beware Signs of White Rot in Garlic and Other Allium Crops (BUL 955)
  112. University of Illinois Extension. Growing Great Garlic
  113. University of Illinois Extension. Growing Garlic info sheet (updated September 2020)
  114. University of Illinois Extension. Overwintering potted plants
  115. University of Maine Cooperative Extension. Bulletin #2063, Growing Garlic in Maine
  116. University of Maine Cooperative Extension. Garlic IPM Newsletter No. 9, June 12, 2025
  117. University of Maine Cooperative Extension. Maine Garlic Pest Field Notebook
  118. University of Maine Cooperative Extension. Bulletin #1206, Blue Mold of Garlic
  119. University of Maine Cooperative Extension, funded in part by Northeast SARE (USDA NIFA). Growing Healthy Garlic: Curing and Disease Issues (Steven B. Johnson presentation transcript)
  120. University of Maryland Extension. Growing Garlic in the Home Garden
  121. University of Maryland Extension. Growing Garlic in a Home Garden
  122. University of Maryland Extension. Fertilizing Vegetable Gardens
  123. University of Maryland Extension. Types of Containers for Growing Vegetables
  124. University of Maryland Extension. Growing Vegetables in Containers and Salad Tables
  125. University of Minnesota Extension. What's wrong with my plant? Garlic: leaves yellow then wilt
  126. University of Minnesota Extension. What's wrong with my plant? Garlic: spots, streaks or blotches on leaves
  127. University of Minnesota Extension. Growing garlic in home gardens
  128. University of Minnesota Extension. What's wrong with my plant? Garlic: undersized or no bulb developed
  129. University of Minnesota Extension. What's wrong with my plant? Garlic: holes in cloves or bulb
  130. University of Minnesota Extension. What's wrong with my plant? Garlic: bulb rotten from the base up
  131. University of Minnesota Extension. Growing garlic in home gardens
  132. University of Minnesota Extension. Growing garlic in home gardens
  133. University of Nebraska-Lincoln Extension. Garlic Production in the Home Garden (G2221)
  134. University of New Hampshire Extension. Growing Garlic in New Hampshire [fact sheet]
  135. University of Tennessee Extension. Garlic for the Tennessee Vegetable Garden (D 75, 2019)
  136. University of Tennessee Institute of Agriculture (UT Crops). Home Garlic
  137. University of Tennessee Institute of Agriculture News (UT Extension). Garlic in the Garden
  138. University of Vermont Extension. It's Time to Plant Garlic! (2023)
  139. University of Vermont Extension. It's Time to Plant the Garlic (Master Gardener intern article)
  140. University of Wisconsin-Madison Division of Extension. Garlic, Allium sativum
  141. US EPA, Code of Federal Regulations (govinfo.gov). 40 CFR 180.175 Maleic hydrazide; tolerances for residues
  142. US EPA, Code of Federal Regulations (govinfo.gov). 40 CFR 180.1 Definitions and interpretations (commodity table)
  143. USDA SARE project report, University of Minnesota. On farm evaluations of novel methods to increase garlic marketable yield (ONC22 to 115)
  144. Utah State University Extension. How to Grow Garlic in Your Garden
  145. Utah State University Extension. Garlic in the Garden
  146. Utah State University Extension. Selecting and Using Inorganic Fertilizers
  147. UVM Extension Agricultural Engineering, hosted by SARE. Postharvest Garlic Trials (slides)
  148. Walters, S.A. (2008), HortTechnology 18(2):286 to 289
  149. Washington State University Extension. Vegetables: Growing Garlic in Home Gardens (FS162E)
  150. Washington State University Extension. Vegetables: Growing Garlic in Home Gardens (FS162E)
  151. Washington State University HortSense. Onions, Garlic: Onion maggot
  152. Washington State University HortSense. Onions, Garlic: White rot
  153. West Virginia University Extension. Growing Garlic (WV Garden Guide)
  154. WSU Extension, Skagit County Master Gardeners. Gearing Up for Garlic Planting Season (2025, Laura Kuhn)