Question
Something's been bothering my hubby & I for years. We have a fairly successful organic veggie garden behind our garage (best spot for light). Due to the constraints of the size of our lot, the garden starts immediately at the back foundation wall of the garage, and extends ~20'x20' at a slight downward angle. At one corner of the garden (immediately against the wall), tomato plants regularly whither and die without producing. The plant immediately next to it will be sickly, but not as bad. Thereafter, the plants are normal and healthy. This year we switched to bell peppers. The entire row of peppers was very small and stunted, although they did produce. The same plants, a few rows down, were far more robust. We add compost (our own) and peat to the soil (lots of clay) every year. We double dig the soil every year. Can you give any suggestion as to what could be causing this failure?

Answer
Actually the answer is really simple....not enough water.  The cement absorbs water, acting like a sponge....we had the same problem in a garden we lined with bricks.  Nothing along the edges did very well, and one day we realized it was heat retention and lack of water.  I would get a non-toxic sealer, and pull the dirt back, and seal the cement with a couple of coats.  This will prevent them from absorbing water.  Plants next to them will still need a bit more water because the cement also retains heat and will dry out the soil, but this a great place to grow heat lovers like tomatoes and cucumbers. Just be sure to the area more water than the rest of the garden.