DIY Solutions

Discovered during the search for a way to rid Hawaiian islands of an invasive non-native species of frog, caffeine has proven to have a remarkable effect upon slugs. Initially targeting an area where the frogs were found it was noticed that large numbers of slugs were coming to the surface and dying.

Caffeine can be applied as a foliar spray or to the soil directly. It makes plants inedible for slugs and snails. Applied to the soil it causes them to writhe about in response to this toxin and die shortly after application.

Concentrations of caffeine similar to that of a strong cup of coffee is effective. Leftovers from your daytime jolt of coffee can be used as a spray. If you have access to coffee grounds then these can be spread around your plants to form a more lasting control.

Caffeine is also present in cocoa, making the use of cocoa shells particularly effective when freshly applied as a mulch.

Caffeine does have a drawback though, continued use over an extended period can cause concentrations to build to levels toxic to plants. This has been given as the reason why coffee plantations become less productive over time. On a domestic scale the effects may be seen after years of use in reduced growth and yellowing in leaves. This is easily rectified by enriching the soil with organic material. The effect of these caffeine laced creatures on any wildlife that eats them is unknown, assumed to have no effect other than to make them strangely attracted to Danish Pastries.