To get a good picture of Romano-British gardens of antiquity, we must consider their prototypes in Italy. Horticulture in primitive Italy, as in other countries, was at its beginning merely intended for practical purposes. Gradually the Latin word hortus, applied in the days of republican simplicity to a field of vegetables, was stretched, at the time of the luxurious emperors, to denote pleasure gardens of the utmost magnificence. In this latter period, the source of every new form of Roman art, including garden architecture, was Greece, which in its turn had received inspiration from Egypt, Persia, and Assyria.

Egyptian gardens are the earliest of which definite records still exist. Pictures and inscriptions, dating far back into the centuries before Christ, show that most Egyptian dwellings were built around a series of courtyards containing vegetation both useful and ornamental. Originally, a row of trees along the inner wall of the building shaded it and the enclosed quadrangle. Later, the tree trunks gave place to solid columns, and the overhanging branches to projecting rafters, which resulted in a general effect foreshadowing the Greek peristyle (columned porch or colonnade) and monastic cloisters.

Religious significance was attached to almost every feature in pre-Christian gardens, and tree worship was observed in all ancient countries. Among the favorites were the pine, the emblem of Cybele, the oak of Jupiter, the laurel of Apollo, the myrtle of Venus, the poplar of Hercules, and the olive of Minerva. The cypress was also grown in many places. Yew, although common, was not much esteemed; instead, juniper and rosemary were often employed for topiary work. Box, too, was frequently clipped, and then, as now, considered the best shrub for edgings.

The rose, the lily, and the violet were among the most distinguished flowers of antiquity, but the narcissus, anemone, gladiolus, iris, poppy, amaranth, immortelle, verbena, periwinkle, and crocus were also cultivated and admired. Many flowerless plants like basil, sweet marjoram, and thyme were grown for their fragrance, while the acanthus was welcome on account of its beautiful foliage. Ivy covered the walls or was trained to form garlands between trees and columns.