In Jain Dharma, there is no widely established scriptural prescription to plant a tree directly with cremation ashes. Traditional funeral rites focus on honoring the departed and disposing of the remains in a respectful way, but planting a tree using the ashes themselves is not a standard or canonical practice found in the Jain Agamas. If a family wishes to memorialize, many people choose to plant a tree separately as a living memorial and keep the ashes disposed in a respectful manner (for example, in water or in a sanctioned burial/immersion), rather than mixing ashes directly with the tree’s planting material. Different Jain communities (Digambar vs. Shwetambar) may have their own local customs, so you may want to consult your local Jain temple or guru for guidance that aligns with your tradition.