Gardening, n.
The art of occupation of laying out and cultivating gardens; horticulture.
Shades of meaning
Fernald has no entry of its own for gardening; he lists it under agriculture.
Where he writes about it:
Farming refers to the cultivation of considerable portions of land, and the raising of the coarser crops; gardening is the close cultivation of a small area for small fruits, flowers, vegetables, etc., and while it may be done upon a farm is yet a distinct industry. — from agriculture
Gardening in general, kitchen-gardening, the cultivation of vegetables, etc., for the household, market-gardening, the raising of the same for sale, floriculture, the culture of flowers, and horticulture, the culture of fruits, flowers, or vegetables, are all departments of agriculture, but not strictly nor ordinarily of farming; farming is itself one department of agriculture. — from agriculture