Bede

Your branches are a paradise of pomegranates, etc. Because the early Church, which was at Jerusalem, produced many people for God from water and the Spirit, it is rightly said that the sacred garden, assisted by the irrigation of the divine fountain, emitted a paradise, not of any kind of trees, but of pomegranates with the fruits of apples. The pomegranates, which bloom with a blood-red color, signify the triumphs of those in the Church who, after the general washing of the sealing fountain, are also baptized with their own blood. …

Commentary on the Song of Songs ↗

Bonaventure

For the soul is a paradise in which Scripture is planted, and it has marvelous aspects of sweetness and beauty. Hence in the Canticle: My sister, my spouse is a garden enclosed, a garden enclosed, a fountain sealed up. Thy plants are a paradise of pomegranates. The soul is a garden in which there are sacramental mysteries and spiritual meanings, where a fountain of spiritual outpourings gushes forth, but it is enclosed, and the fountain is sealed up, for they are not visible to the impure, but to those whom God knows to be His. …

Collations on the Hexaemeron, Collation 17 ↗

Robert of Tombelaine

What does holy Church send forth, if not holy words together with holy works, by which she begets and nourishes her children? When she leads some all the way to martyrdom and instructs others in holy conduct — sending the former, red with the blood of martyrdom, to the eternal homeland, while presenting the latter, living in holy works, to their neighbors as an example of holiness — what else does she send forth but pomegranates and the fruits of fruit trees? …

Commentary on the Song of Songs, Chapter 4 ↗