Step 1: Basic Frame
Cut 4 legs the same length.
Cut 8 side bars to the length you'd like the width of your planter.
Step 2: Frame Assembly 1
The lower side piece shouldn't touch the ground to avoid water, I left around an inch free.
Step 3: Frame Assembly 2
Step 4: Side Panels
Since I was using lots of different pallets here, I attached the boards in a random order to give it that rustic look.
I used nails for the sides as they look nicer and aren't load bearing. Try and re-use the nails you took out of the pallets if they're straight enough
Step 5: Top
Cut these pieces at 45 degrees to make a nice looking top.
Step 6: Done
Instead, I used an old bin to put the plant in. Hopefully whatever you plant will hide a bit of the bin or barrel.
The other pictures show another planter I build from half a leaky water butt.