Question: I planted red and new potatoes in early May. They were planted 6-8 inches deep. The potatoes were sprouted potatoes from our local hardware store. Our soil is heavy clay but the potatoes were planted in purchased hummus which had been worked into the soil to a depth of about 15 inches. Our climate zone is zone 9B. 

[![No potatoes image 1](https://i.stack.imgur.com/A8pEG.jpg)](https://i.stack.imgur.com/A8pEG.jpg)

[![No potatoes image 2](https://i.stack.imgur.com/qXDvJ.jpg)](https://i.stack.imgur.com/qXDvJ.jpg)

As you can see, the potato plants only grew to about 1 ft high. Some of the plants dried up so we started harvesting today (Aug 13). To our surprise, there were no potatoes at all. We watered the potatoes using a drip system (2 GPH) that was set to 15 minutes once per week. However, the summer here has been very hot and whenever the plants looked wilted, we added an additional watering cycle.

Answer: 
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> However, the summer here has been very hot
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This might very well be the reason. Potatoes tend to stop the production of tubers once the soil reaches a certain temperature. Gardeners that plant their potatoes in dark plastic bags and unwittingly put the bags into a sunny spot often have the same problem.

Next year, plant your potatoes as early as possible to get a long growing phase before the summer heat sets in.
In addition to the answers above (*especially* regarding the need to improve the soil) you should be prepared to periodically mound more soil or mulch or straw around the plants as they grow. The tubers actually grow along the stems of the plants, so if you don't cover them up, you may grow larger plants next year, but they still don't produce a crop of any size.

There are loads of resources online that outline "best practices" for growing any vegetable. Have a look and plan for next year.