That's an excellent question! Caring for your wooden park bench is key to making it last for years. There's no single universal schedule, as it depends heavily on your local climate and the type of wood. However, a good general rule is to inspect and likely re-oil your bench once a year.
For benches in harsh, sunny, or very wet climates, you might need to do it every 6-9 months. In more sheltered, mild conditions, you could stretch it to every 18-24 months. The best approach is to watch for the signs your bench is thirsty: the wood will look dry, faded, or grayish, and it will no longer repel water (water will soak in instead of beading up).
Use a high-quality outdoor wood oil, like teak oil or a dedicated hardwood oil. Start with a clean, dry bench. Apply the oil generously with a brush or cloth, following the wood grain. Let it soak in for the time recommended on the product, then wipe off any excess. The best time for this job is in mild, dry weather.
Sticking to this simple routine will preserve the wood's natural beauty, prevent cracking and splitting, and ensure your bench remains a comfortable and welcoming spot for everyone to enjoy.