Step One: Purchase a wicked, Eco-friendly and recyclable, 18 inch (depth) container to do your planting in. Then get your Tim the Toolman grove on and drill some holes into the bottom of it (for your water drainage system to work).
Step Two: Fill the bottom of your tub with rocks, preferably pebble like rocks which can be purchased at any garden centre or if you are really, really bored and have the time, hit a gravel or rocky road and start collecting!
Step Three: This is an optional step but it was suggested by my father, and I think it's a great idea, to add a layer of crumpled newspaper. The newspaper will help absorb excess water. And this newspaper gets extra bonus cool points since it comes from the remains of an old NOW magazine paper.
Step Four: This option is NOT optional seeing as earth is necessary for plants to grow in. What is optional is your choice of dirt. In this case I am using a combination of peat moss (light, fluffy and dusty dirt) with organic potting soil (dark and moist).
Step Five: Start adding your pretty little lettuce plants to the pot. I planted four in total plus a couple of strawberry plants which I learned grow well next to lettuce ... unless of course the Internet lied to me.
Step Six: Proudly display your new lettuce Greens/strawberry garden and take of picture of it. Oh, and it's a good idea to water your plants at this point it just at wee bit.
Lettuce and strawberries do need a sufficient amount of water, especially during the early stages of growth but be sure not to over water your plants. Your new water drainage system will help!
holes + rocks + paper = Happy Plants