Although outdoor wicker furniture is quite durable, it will last longer and keep its good looks for many more years if you give it some protection from the elements. Here are two suggestions that work well and can be done in just a couple of hours.
The first thing to do is to make sure that you're wicker furniture is clean before you apply the treatment. You can't skip this step or else you could end up just trapping harmful dirt and mildew underneath the protective finish. This won't look good and will just lead to your furniture rotting.
Begin by vacuuming your furniture using the soft brush attachment and vacuum cleaner hose. This gets rid of any dust and bits of dirt and food crumbs that are trapped within the wicker fibres.
Make up a mild solution of washing-up liquid and warm water, and use a clean sponge to thoroughly clean the furniture. Rinse off any residual soap suds with a garden hose under low pressure. Note here that a power washer is not suitable for cleaning wicker furniture; the jet of water it produces will be too strong and may damage the wicker.
Wipe away water droplets with a squeegee to avoid evaporation marks, and then allow the furniture to air-dry completely.
Wicker furniture looks great when painted to match your patio colour scheme. You can obtain paints specifically formulated for use on outdoor wicker furniture from good DIY stores.
When the furniture is completely dry, you should use a small, standard paintbrush to apply your chosen paint to the wicker, taking care to cover all the seams and get right into the corners. Paint rollers don't work very well on wicker as the end result tends to be patchy, so always use a brush. Make sure you cover the whole of the furniture including underneath the seat and arms.
Allow the paint to dry completely, and then use a clean paintbrush to apply a coat of marine varnish to fully waterproof the furniture. When the marine varnish has dried, apply a second coat.
If you prefer a completely natural finish, you could just choose to omit the paint and apply three coats of marine varnish instead, allowing each to dry before proceeding to apply the next. Whichever option you choose, you'll need to refinish your furniture every couple of years to maintain the protection.
If you don't want the job of painting or varnishing your outdoor wicker furniture, you could opt to treat it with Tung oil instead. Tung oil dries to form a hard, plastic-like coating, and this makes it perfect for keeping harmful damp out of the wicker fibres. You can buy Tung oil from good DIY stores.
When your furniture is clean and dry, simply use a clean cloth to apply the oil generously to the furniture, making sure that you cover all the seams and crevices. To keep your furniture protected, apply a dressing of Tung oil at the beginning of every new summer season.
You can extend the life of your wicker outdoor furniture and keep it looking good by applying one of the finishes suggested above. All these options are quick, cheap and easy to apply. At the end of the summer, give your furniture further protection by storing it under cover, or putting it in a sheltered spot out of the wind.