Answer: In a raised bed situation, it is important to add ample organic matter to the soil mix. I would suggest adding good quality compost to the existing dirt and sand. The total volume should be roughly one third compost. This would be better than topsoil and peat moss.
If you are unable to get compost, then you could use peat moss and/or other organic material such as well rotted autumn leaves for that organic third of the mix. This should give you a soil mix that holds both water and air to provide a healthy environment for the roots.
Unfortunately, most vegetables really need sun all day or for a bare minimum of six hours including the hour of noon. In less sun, they tend to be leggy and weak and do not bear a good crop. Since you already have the box, you might try growing a few of the slightly shade tolerant vegetables such as peas, spinach, lettuce and other greens. If you truly want to grow tomatoes, try cherry tomatoes. As far as herbs, again most prefer full sun. You might try parsley, chives, mints (in a container sunk in the ground to prevent invasive roots) and basil.
Good luck with your garden this summer!
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