There are a lot of options when it comes to outdoor planters, from simple terracotta to modern ceramic to classic carved stone. One material people sometimes overlook, for fear that it won't be able to withstand the weather or won't age well, is wood. Wooden containers work in almost any garden setting -- and though wood does tend to age and deteriorate when exposed to the elements -- proper sealing can keep your wood planters looking beautiful.
Choose the type of sealant you want to use. Plant safe sealers exist, but must be reapplied regularly. An easier option is a commercial-type sealer, which will last longer. But if you go this route, it's important to line your planter to protect the soil inside from the harsh chemicals.
Apply the sealer to your planter. Cover both the outside and the inside, and remember to coat the bottom as well. Make sure to cover pockets, knots and corners to prevent leaks into the wood.
After applying a coat or two, let the sealer dry for 24 hours. Then test a small area by wetting it with a few drops of water. Wait a few minutes to ensure that the sealer is working and the water isn't being absorbed
If you went with the plant-safe sealer, your planter is ready. But remember that you'll have to reapply the sealer in a few months, so lining the inside may be helpful when it comes time to recoat the inside of the planter. To create a liner, follow the steps below.
Commercial sealer is recommended so that the planter is easier to empty and reseal somewhere down the road. You can use plastic plant liners from a garden supply centre, or if you can't find any to fit your planter, you can cut pieces of heavy duty plastic drop cloths.
To use drop cloths, cut a piece of plastic large enough to cover the inside of your planter. Cut a few holes in the bottom of the liner for drainage. Line the planter with the plastic and hold the liner in place for the time being with clothespegs or binder clips. Trim the lining so that it reaches just the top of the planter. Line the bottom of the planter with stones, which will help prevent your drainage holes from getting clogged.
Fill with soil. Keep the level of the soil about 2.5 cm (1 inch) below the liner to prevent water or soil from spilling over. Remove the clips.
Commercial-grade sealers should last a season or two before needing to be reapplied. And when that day comes, the plastic liner will help you transfer the plant out of the planter while you reseal.