Plants, in general, represent knowledge, ideas, and intellectual concepts -- things of the mind. Plant the best and most beautiful of those in one place, give them plenty of water (truth from the Lord about day-to-day things), plenty of sunlight (the Lord's wisdom) and warmth (the Lord's love), tend them to keep the weeds (false ideas) out, and you get a garden. So it makes sense that a garden in the Bible represents the intellect, where with proper care we can nurture the best and most useful ideas and ways of thinking.

(Referenties: Arcana Coelestia 98, 100, 1588; Heaven and Hell 111)

100. That 'a garden' means intelligence and 'Eden' love, is also evident in Isaiah,

Jehovah will comfort Zion, He will comfort all her waste places, and will make her wilderness like Eden and her desert like the Garden of Jehovah. Joy and gladness will be found in her, confession and the voice of song. Isaiah 51:3.

Here 'wilderness', 'joy', and 'confession' are terms used by the prophet to express the celestial things of faith, that is, things that belong to love. But 'desert', 'gladness', and 'the voice of song' express the spiritual things of faith, which in turn are matters of the understanding. The former relate to 'Eden', the latter to 'a garden'. For throughout this prophet dual expressions for the same thing are constantly occurring, with one expression meaning celestial things, the other spiritual. For more about what the garden in Eden means, see at verse 10 below.