Not sure if these can be of any value but here are some pictures.

Box 1
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Box 2
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How deep are you planting them?

To get a quick idea of your soil's probable pH, just call your local Cooperative Extension Office, ask for the Master Gardener (see link below). Deserty soils do tend to be alkaline.

Watermelon and lima beans prefer a pH of 6.0 to 6.8, but Texas has a great reputation for watermelons.
If your soil is very sandy, the heat may be drying out the sprouting seeds and killing them. Re-sow, moisten soil well, then try covering your seed bed with a single sheet of newspaper held down with rocks or bricks, and start checking for sprouts after 3 days for watermelon, 5 days for lima beans, 2 to 3 wks for NZ spinach.

Radishes are usually a cooler-weather crop, so try again in fall when the weather is cooler.

There isn't any possibility that bird or animals are digging up the seeds, is there? I lost a whole corn crop to crows and blackbirds once.

Sue

Here is a link that might be useful: U.S. Cooperative Extension Offices

Sorry I'm so late responding. Had some minor surgery which took me away from my beloved computer.

@taz6122 - Not too deep. I think when I first asked a similar question I was given the advice about depth.

@Sue - I'll check the PH , the top level of soil is a mixture of miracle grow garden soil and bagged cow manure soil mix. Not sandy at all from what I can feel. I appreciate the advice and will give it a try.

Since this post I had replanted Limabeans in another box and again in the same box mentioned above and the lima beans in the other box are taking off where the original box I started with only has two which germinated. Next year I'm going to retill that entire box and add fresh soil and maybe that will help.

Could it be that the box is draining so fast that the top layer gets too dry before germination occurs. I would try this: Soak the bean seeds for half an hour, then wrap them in a lightly damp paper towel and put it inside a small plastic bag. Leave the top unzipped so there is air. As soon as they sprout, put them into the bed and see if they will grow. My guess is that you are having a moisture problem.

The problem is clearly not pH. To affect germination pH would have to be way way off the scale. Most likely the seeds are drying out before germination. Water more often or plant deeper.

I agree it is not pH - bagged consumer product soil is just fine in pH. Since the OP hasn't described how the soil felt when they stuck their finger in to see if it was dry, I suspect the soil is too dry. Stick a finger in when you get home. If your finger is dry after a couple samples, then the soil is too dry. Raised beds dry out faster. Mulch.

Dan

Thanks for the feedback, if it's water issues then I'll give some mulch a try. :) What mulch do you recommend ?