I assumed you checked the other two sparkplug tubes on the drivers side for water too. If not, also check those. Dry any moisture found.
Hosing down an engine with the garden hose, is generally a bad idea, as electrical connectors can get water in them, and cause a short. Water can also corrode the contacts in those connectors. The connectors are generally water resistant, but they don't always seal as well as you would like.
If checking and drying the sparkplug wires and coils doesn't solve the issue, I'd start checking all of the electrical connectors in the engine bay for moisture.
Hosing down an engine with the garden hose, is generally a bad idea, as electrical connectors can get water in them, and cause a short. Water can also corrode the contacts in those connectors. The connectors are generally water resistant, but they don't always seal as well as you would like.
If checking and drying the sparkplug wires and coils doesn't solve the issue, I'd start checking all of the electrical connectors in the engine bay for moisture.