Why would a gardener be interested in grafting vegetable plants?
Grafting, in general, is a common method for propagating plants by carefully joining cut plant parts so they grow together as one plant. Many plants can be propagated from seed or from cuttings that put out new roots. Others — like apples — don’t “grow true’” from seed or root easily from cuttings and must be grafted. Every apple you’ve ever eaten is from a grafted apple tree (unless you’ve eaten crabapples), for which a small branch cut from a desirable apple tree was then grafted onto the trunk of an apple variety with desirable roots.
The reason why many fruit trees are grafted is because they do not grow true to seed. Only by grafting the scion wood (a cutting of a branch) from the original tree onto another rootstock (the base another tree with roots) can you ensure that you get the same fruit each time.
Seedling grown trees
If a fruit tree is not true to seed, the seedlings will be different from the parent, and they will often take many years longer to fruit, in some cases, well over ten years. That can be disappointing if you wait that long only to find that the fruit tastes nothing like the parent tree’s fruit!