The Vine Cross is known in heraldry as a Foliated Cross or erroneously, an Ivy Cross. Curiously, it is not a common Christian symbol. We feel it should be seen more, and here's why:
In John 15:1-3, Jesus calls himself the vine, and that Christians are the branches of that vine. Even those of us without 'green fingers' know that it's the branches that bear fruit. Jesus (the vine) mediates between God and man.
And we also know that fruit will grow if, and only if, the vine has roots which can deliver moisture from a rich soil. In our analogy, the root of the vine resembles the Holy Spirit. The root is unseen, but we know it is there because the plant flourishes and bears fruit.
If we think of God being like a gardener, nourishing the vine, then if a branch bears no fruit (if we have not loved as we should), the gardener cuts it away. It is good for nothing and damned to be consumed by the bonfire. However, if the branch bears fruit then the gardener is pleased. The fruit is harvested and as a result, the branch is in a stronger state to produce yet more fruit.
There are many of us human branches yet we all share the same vine and the same root. The branches travel in different directions; some have high positions, some low. Some are old branches and some are young. Some grow in the sunshine, overlooking the beautiful garden and others find themselves in the shade, facing the compost heap. Yet we all share the same vine and the same root. And the same Gardener tends to each branch with the same love, knowing that branches can be weak. God loves us all, whatever our position may be.
And the grapes? These are the products of our Christianity; whatever God has called us to produce.