We prefer Martins Premium Potting Mix but there are a few brands out there that are equally good. Expect to pay around $12-$15 per 30 litre bag for a good quality mix. Make sure you use a Potting Mix rather than any other sort of mix as they designed to drain freely and contain moisture beads and fertalizer to get things off to a good start.
We can tell you the volume in litres on all our pots and they generally do require that much potting mix to fill them, it will seem a lot but it does pack down.
You can seal the inside of the pot but it is not strictly necessary. If you don't seal the inside you may get some moisture coming through to the outside of the pot which may affect the appearance of the pot. In some cases this matters, in other cases it doesn't. If it would matter to you then seal the inside of the pot with an all purpose pot sealer. Something like Yates Pot-a-Seal is fine.
More information on sealing pots is in our Sealing Outdoor Pots section.
Think about how the pot will drain. Both the pot and the plant need water to be able to flow through freely. If the mix becomes overloaded with water then the plant will suffer, and the pot can be weakened.
Pot feet are often a good idea as they will raise the bottom up 15 - 20 mm to allow any water to drain through and also prevents water pooling and excessive marking of tiles / decking / concrete underneath. Your local hardware store should be able to supply these, or check with us as we can often supply them also. Also read our section on Leaching In Pots
You are expecting this plant to live in the pot for some time! The more soil in the pot the more moisture the soil will retain and the more the roots of the plant will spread out. This creates a healthy root system which in turn creates a healthy plant.
Now for the fun part, planting!!
Place some mesh over the drainage hole at the base of the pot. A piece of geo-fabric or even a piece of fly screen mesh about 15cm square to cover each drainage hole. You can usually buy small quantities off a roll at a hardware store.
Open the top of the bag of potting mix and tip sufficient in to fill the pot to the base of where the plant will sit. Pack the soil down as you go and keep testing your plant (still in it's plastic pot) until the top of the plastic pot sits level with the top of your new pot.
Once you are happy that your plant is going to sit at the right height remove the plastic pot from your plant and sit the plant in place. You can usually do this over the new pot so that any lost soil falls into the pot rather than all over the ground. The plastic pot should be relatively easy to remove by simply squeezing the sides then sliding the plant out. The soil should remain in place as long as you are relatively gentle when removing the pot. You shouldn't need to disturb the roots unless the plant has been in the plastic pot for some it. If this is the case then gently tease the roots out while the plant is sitting in the new pot.
Fill around the plant with more potting mix and pack it down as you go. A soil scoop is ideal for this job but if you don't have one use a cup or a small jug. Using something to scoop the soil out and tip it into the pot means less mess. You can use your hands, you should probably be wearing gloves, but this is usually messier.
Top the pot with pebbles if you are using them, otherwise use pine bark or some other mulch to retain the moisture then water well. When watering a potted plant you should water the soil rather than the plant. If you ensure all the soil in the pot is moist then this encourages the roots to spread out looking for moisture which creates a healthier plant.