Horticulture/Lichen

Uses
Lichen are mostly used to add a feeling of age to a place (because of how slowly they grow), and are an indicator of clean air (because they are vulnerable to air pollution). They can also add gentle or striking colors in unlikely places.

They are particularly well-suited to:
 * rock gardens
 * stone walls
 * stone borders
 * roofs
 * tree bark (either living or dead – lichen doesn’t damage trees)

Because lichen can survive for long periods without water, they are well-suited to xeriscaping.

Cultivation
How to grow lichen: if an environment is conducive to lichen, it will eventually grow. If it is not, then it is difficult to force it. Naturally, it will grow very slowly, on the order of millimeters per year, but with nutrients it can grow much faster – you don’t need to wait centuries to have lichen-covered walls.

If there is lichen in the area, or you have reason to think that it could grow (say, it used to grow), you can encourage the grow as follows:
 * Put nutrients on porous rock, and it’ll grow rapidly.
 * Add ground up lichen, and it’ll grow instantly.
 * Yogurt and sugar water work as nutrients.

Specific recipes:
 * lichen slurry/milk shake
 * 1:50 lichen to yogurt, such as 10 ml ground up lichen + 500 ml natural yogurt


 * spray sugar water weekly
 * 1:40 sugar to water, such as 5 ml sugar + 200 ml water or 100 ml sugar + 4L water.
 * Even w/o adding lichen, one should see results after a month or so.