| Company |
| I Must Garden |
| Idaho Seeds (Seeds4u) |
| Idea Spectrum, Inc. |
| IDeal Garden Markers |
| Ideal Poultry Breeding Farms, Inc. |
| Ideas Genie (ideasforgardens.com) |
| Idle Wild Herbs |
| Idlewild Farm, Inc. |
| iGifts2Go |
| ihort (International Horticultural Technologies, LLC) |
| ILLexotics |
| Illinois Paradise Farm & Plant Nursery |
| iLoveOrchid.com |
| Imberhorne Lane Nursery (CamelliasOnline.co.uk) |
| Impecta Handels |
| Imperial Daylilies (imperialdaylilies.com) |
| Impressive Irises |
| In Harmony Herbs & Spices |
| In The Country Garden & Gifts |
| In the Neighborhood Daylilies |
| In2iT Gardens |
| Indian Bayou Daylilies (Hilliard Lawler) |
| Indiana Berry & Plant Co. |
| Indoor Gardening Supplies |
| Indoor Window Gardening |
| Infinite Gardens |
| Ingoldsby Nursery & Floral Shop |
| Ingwersen Birch Farm Nursery |
| Inmobiliaria Oasis de la Campana S.A. |
| Inner Coast Nursery |
| Innovative Growing Solutions (IGS Hydro.com) |
| Inside Out Home and Gardens |
| Inside Passage |
| InstantHedge |
| Institute for Aloe Studies |
| Inter-State Nurseries |
| Interior Gardens |
| Intermountain Cactus |
| Intermountain Native Seeds |
| International Bulb Company |
| International Garden Products |
| International Greenhouse Company (IGC) |
| International Iris |
| International Irrigation Systems |
| International Technology Services, Inc. (bugsandbees.com) |
| Interplex Solar, LLC (Solar Nite Eyes) |
| Interseeds |
| Interstellar Gardens |
| Ion Exchange |
| Iowa Adirondack Company |
| Iowa Grape Vines |
| Iowa Horticulturist Magazine |
| IPM Laboratories, Inc. |
| IPM of Alaska |
| Ireland's Worm and Garden Supply |
| Iris Acre Farm |
| Iris City Gardens |
| Iris Colorado |
| Iris Fan Gardens |
| Iris Haven |
| Iris Hill Farm |
| Iris Hills Farm |
| Iris Madness |
| Iris Mart (c/o Liberty House Company) |
| Iris Nut Garden Plants |
| Iris Oasis |
| Iris of Sissinghurst |
| Iris on Parade |
| Iris Sisters Farm |
| Iris4U Iris Garden (U & I Enterprises) |
| Irises on the Hill |
| Irisgal.com |
| Irish Eyes Garden Seeds |
| Irish Gardens |
| Irish Lilyput Nursery |
| Irish SeedSavers Association |
| Iriswarehouse |
| Iron and Wood Garden Tools by Fisher Blacksmithing |
| Iron Gate Gardens |
| Ironweed Native Plant Nursery |
| Ironwood Estate Orchids |
| Irrigation-Mart.com |
| Irrigo (International Irrigation Systems) |
| Isabel Hibbard's Daylilies |
| Island Dahlias |
| Island Daylily Farm |
| Island Grove Ag Products (Nursery Division) |
| Island's Bamboo Gardens |
| Ison's Nursery & Vineyard |
| IsoWeeder (PlasTech Designs, Inc.) |
| It's About Thyme |
| It's Paradise At Home |
| Italian Seed and Tool |
| Italian Seed Company |
| Itasca Ladyslipper Farm |
| Iverna Herbs |
| Ivies of the World (Point Seminole Fernery) |
| Ivy Garth Seeds & Plants, Inc. |
| Ivycroft Plants |
| Iwasaki Bros., Inc. |
| Izel Plants |
