What are grafted Gardenias?

Grafted gardenias are grown on the Gardenia thunbergia root stock which is resistant to root knot nematodes. As this rootstock is also generally more vigorous, grafted plants are more long-lived, more disease-resistant, and the plants have better color than non-grafted plants. If you live in an area where gardenias are typically more difficult to grow, grafted gardenias, which tolerates poor soils and more readily takes up soil nutrients, are the better the option.