Bounties attract serious brainpower to the challenge.
This idea was inspired by this creative contribution by Juran.
The idea is to have a flower pot made of wax or other solid, flammable material with the wick circularly twisted inside it like a coil to allow slowly burning the whole thing like a candle and melting the wax to expose the soil in which the plant is placed.
Such pot would be placed in a hole dug in the ground where it is supposed to be planted. The hole should be made bigger than the dimensions of the pot to allow enough oxygen to reach the pot-candle for it to burn well.
Here are a couple of pictures to help imagine better how such a candle-pot would look like and how the burning of it would work:
The twisted wick could simply be embedded in the walls of the wax pot similar to that shown in the first picture, it doesn't have to be surrounded by a wax tube like in the second picture.
The very bottom of the pot could be made of paper or a thin layer of some other biodegradable material. Or it could be removable and a person would take it off before putting the pot in the hole.
A hole could also be made deeper than the height of the pot for its walls to protect the candle from being blown out by the wind. For additional protection from the elements, a transparent cover could be placed above the hole with holes in the sides of it to allow the oxygen to pass.
Why do this:
A unique and beautiful way to plant something.
The fire element adds an additional ritualistic component to the planting experience therefore it could enrich the situations where the plant is planted for/during special occasions, especially funerals, but also might be wedding, baptism, or just simply planting a tree with your kid, etc.
The ingredients of the burning material could perhaps be formulated in a way that the combustion products would additionally fertilize the soil and help the plant to grow better.
Depending on the size of the pot, such a candle would burn at least a few days till the wax totally melts/evaporates. The burning time can be reduced by making the walls of the pot as thin as possible. The specific formulation of the burning material could also be made to speed up the burning if desired. After the pot-candle stopped burning, the "gardener(s)" come and remove the rain/wind cover, fill up the hole with additional soil, and water the plant.