My Basil Leaves Are Burning!

I began with three basil seedlings and one by one slowly they disappeared, leaf by leaf (literally)!  And now sadly I'm down to one basil seedling and by the looks of it it isn't going to be around much longer.  My initial thought was that the sun exposure was too much for these tender leaved little dudes, but I had planted them under a rather tall rose bush that would give them a bit of shade and a bit of shade is what they got.

I looked to my handy dandy growing book, flipped to the basil section,

"Keep the soil moderately moist, but allow it to dry out ever so slightly between watering.  If there is one thing basil doesn't like, it's sitting in cold, soggy soil.  Yet for a sun- and heat-loving plant, it is surprisingly temperamental about light.  It took me years to work out that too much midday sun can burn the leaves, especially when it comes to the soft and tender varieties."  - Gayla Trail, Easy Growing

My suspicions about too much sun burning off the leaves of my basil was somewhat confirmed, I find that when it comes to planting and growing it is often difficult to know exactly what it is that's killing your plant, there are just so many factors that come into play.  Is it the sun?  Is it over-watering?  Is it too moist?  Too dry?  The list goes on.

In efforts to save my last but sickly looking basil seedling I created a kind of biosphere to keep in the warmth while adding more shade.  I used an old plastic strawberry container, wrapped it in saran wrap, poked holes in the wrap for ventilation and placed it so that the basil seedling was enclosed in it.  It was definitely a fly-by-the-seat-of-my-pants idea and I'm not quite sure it'll work in my endeavors to keep the warmth around the basil but we'll see soon enough.  For added shade I threw over an old small bath rug on top of its cage.