Wood can last a long time if you care for it properly. This involves cleaning it properly, sealing it and preventing too much moisture from soaking into the wood. When the wood gets wet it will dry out and carry out some of the moisture in between the cell walls inside the wood. This can cause the wood to shrink and warp. Warped wooden gates may not open and function properly. Prevent this from happening by caring for the gate properly.
Use screws rather than nails to put together the wooden gate. The screws will hold the wood together better than nails and will help prevent warping.
Paint the wooden gate with a sealant that will prevent the wood from soaking up water. This sealant will cause the water droplets to form on the surface of the wood without soaking into it. Reseal the wood once you notice that these droplets no longer form.
Wring out a sponge that holds a cleaning solution as much as possible before using it to clean the wood. This will prevent you from applying too much water to the wooden gate.
Don't pressure wash or spray the wooden gate with a hose. This will soak the wood and can damage it. Use pressure-treated wood, which is less prone to warp than plywood or hardwood.