Is ash worth adding?

I was just watching a video from Strain Hunter or something like that. Some of the local growers in Africa were saying they were fertilizing with ash. My guess would be ash from burning fields so likely a lot of plant matter as opposed to ash from trees. What do I know, ash has to be ash right? The plants i'm concerned about are in a fresh potting soil and growing in doors with about 600w equivalent cfl's 18hours daily. I was thinking ash from the bbq oven might be worth adding. Yes, no? It's all natural!

Burning leaves, twigs and grasses produces potash, crude potassium carbonate, which is water soluble and readily available to plants.

Spreading ashes is only useful if you have a potassium deficiency and it's a very imprecise method of supplying nutrients to a potted plant. Also, depending on the fuel source for your bbq, you may well disturb the pH, if not poison your plant.