Minerals like potassium are often found alongside caffeine when it
occurs in plant sources like coffee beans, and that could help the
plant grow faster. But the caffeine itself would be unlikely to
have any affect on the plant's rate of growth.
I tested it and the plant grew at normal rate but the leaves
were more wrinkly and browner
Caffeine does not do anything to a plant directly. But caffeine is
used by many plants as an natural insecticide which paralyzes any
poor insect unlucky enough to start eating the plant. Larger
mammals and primates like humans find it has a minor stimulant
effect but in higher doses it acts like the intended insecticide
effect, causing tremors, extreme anxiety, muscle problems,
tachycardia, and sometimes death. Yup, caffeine is just a
insecticide that is mildly stimulating. Kind of how they used to
use strychnine as a stimulant.
Although you can use either a thin or thick layer of coffee
grounds, make certain you do not cover the grass to the point that
water is repelled. Watch out for gophers that might be attracted to
your coffee grounds fertilizer. On the plus side, earthworms will
also be drawn to your unique fertilizer.Since earthworms have the
ability to eat enough in a 24-hour period to equal their body
weight, your lawn will benefit.