Think about it this way. When sun is low, tall plants will cover sun for the lower plants behind them. When sun is low? In the morning and afternoon. Most important is morning sun. So plant the way your lowest plants closer to the side where sun rise. And arrange plant types by height this way. In afternoon, most east plants will be in the shade of taller plants , but it is not bad - afternoon sun is hot and not that important to the plants. When sun is high the shadows are short, and basically just under the plant, so for mid day it doesn't matter how you plant. I hope this helps. So for your descriptions it would plant from left to right tomatoes, melons , cucumbers(if they are not on trellis, otherwise they should be to the left of melons) I hope this helps.

Galinas, thank you so much for breaking it down to 4th grade level. The program is right then. Tomatoes to the left of melons and cucumbers. I am trellising everything on this bed on a 4 x 25 bamboo teepee thingamajig. Help me with the last sentence. "...cucumbers (if they are not on trellis, otherwise they should be to the left of melons)". I am assuming that the "they" is the cucumbers. So trellised cucumbers should be left of melons, thereby giving me from left to right, tomatoes, cukes, melons. Correct? Thank you again!!!

In general, low plants should be on the south side, and tall plants on the north, if you're trying to maximize absorption of sunlight. Afternoon sun is just as important to plants (from the point of view of photosynthesis) as morning sun. If your plants do tend to get highly stressed from afternoon sun, then I suppose it makes sense to bias the shading to then. But if not, then don't worry about it.

In many places one tends to get sun preferentially in the morning or afternoon. Might want to give that some thought as well.

What I mean, if you use trellis for cucumbers, but not on melons(as melons better grow flat, that up) then cucumbers will be higher and melons will be lower. If you use trellis for melons as well, and height will be the same for cucumbers and melons , then plant the way you have easier access to cucumbers - you will access cucumbers much more often then melons.