Start with a pot
This square contemporary planter is all the craze right now. It's made of a specially spun fiberglass material and designed to look like a rustic cement block but is much stronger and only weighs a couple of pounds. Look for the "Asian Ceramics" brand at your local garden center or nursery.
Cover the hole with a screen
Your pot must have a drainage hole at the bottom, otherwise water will sit at the bottom, mold and grow disease. Cover it with a piece of used screen. If you don't have screen, just use a rock that is slightly bigger than the hole to cover it up which will stop soil from seeping but still allowing extra water through.
Cover the screen with rocks - optional
This isn't necessary but rocks help hold the screen in place when you start packing it with soil and also helps a with drainage so that the hole doesn't get clogged with soil over time.
Fill with potting soil
Use a high quality potting mix. The better soil you use, the better your plants will look. I used Miracle Gro Moisture Control Potting Mix. Never use soil from your garden because it could have insects and diseases in it.
Pat the soil down
Pat the soil down. Leave room for your plant. I'm planting an agapanthus and I want to make sure that the top of the root ball (the dark brown part) isn't higher than the rim of my pot.
Finish filling soil
Again, make sure you leave room a couple of inches from the top. Most people fill it right up to the top which doesn't leave any room for mulch or water.
Mulch will help add a nice decorative finish to the plant. I used a black bark because it will give a nice contrast from the light pot. Mulch also serves a practical purpose by keeping the soil cool when it gets too hot.
Again, again, again!
Leave some space from the top of the pot so that the water doesn't leak out when you water it.
Add a rock
A rock can add dimension to a simple contemporary planter. Plus the rock's round shape helps visually soften the sharp corners of the pot.
Water (with a twist)
Your initial watering should be spiked with some Superthrive which will give it vitamins and nutrients and ultimately the best possible start.
Remember, whenever going for a contemporary or modern style planter, less is more. Keep it simple. This agapanthus doesn't look like much now but in just a couple months it will send up it's blue powderpuff flower and look stunning!