Swapping your old lawn timer for a smart controller stops you from watering the grass right before a rainstorm. The physical setup takes less than an hour, and spring is the best time to do it because local water utilities routinely offer rebates to cut down on summer waste.
A solid smart controller runs about $250. If you combine a utility rebate with a zero-interest card window, you can break that total into tiny monthly payments without paying extra in interest.
Keep in mind that an intro APR window is a strict deadline, not free money. If you still have a balance when the 18 months end, the card's standard variable rate applies to whatever is left.