Anything is possible, but I doubt the soil is to blame. I'm sure others will chime in about pest control.

My wife is sure that the cheap bags of soil we purchased at our local home center had the beetle eggs or larvae already skulking in them.

Well, this may or may not be true. But sometimes you get what you pay for. Cheap soil does not mean quality soil.

Go to the following links of these people who have literally created raised bed vegetable gardens, describe them in detail, and use the following growing medium in the frames they constructed:

* 1/3 Peat Moss - available at any garden center or supermarket.
* 1/3 Vermiculite - Buy the coarse grade in large 4 cubic-foot bags at any garden center.
* 1/3 Blended Compost - created from at least five different materials, not just one so as to provide a balanced diet. It is the only source of nutrients these vegetables get from their soil because it's all they need:

Examples Page 1
Examples Page 2
Examples Page 3
Examples Page 4
Examples Page 5

Here is a link that might be useful: Raised Beds Thread for You to Browse

Thanks for the links. I'm happy to see that info. Thankfully the sunflowers and tomatoes aren't too damaged. In fact, we've just begun harvesting seeds out of the dried sunflower heads. Great fun for the kids!

did you just use topsoil? the .98 bags of dirt you can get at Home Depot. Those really dont have any good organic compost (or anything really). I have 4 raised beds , I put in in March. I used bags of compost and bags of garden soil.
>>>>We put in some corn, tomatoes, sunflowers, watermelon, cucumber, pole beans and pumpkin.>>>>
I am by far not a expert and I may be terribly wrong, but I think these plants get way to big for a 4X4 raised bed. Well at least the watermelon , cucumber and pumpkin.

I loved growing sunflowers last year. did you grow any giant ones?

I go to a soil place that has different mixes of soil/compost. I think it's about $24 for a truckload, which would probably fill your 4x4 area.
Remember that watering and the winter rains will result in your new soil to settle. I had to buy another truck load the next year and am ready to buy another 4 yrs later.
I also add compost each year (home made), chicken poop, aged horse poop, goat poop (goat and rabbit can be fresh, horse and chicken need to be aged or composted)
HTH Nancy

Soil is probably THE most important part of having a good garden. Replace half the "cheap soil" with compost. Start your own compost pile.

And those do sound like way too many/big of plants for a 4x4 area, even two of them.