Q.why won’t root crops grow in my garden
My garden grows great beans and tomatoes, but root crops either go to seed immediately or put nothing underground, like potatoes or radishes.

Most root crops need somewhat cooler temps and loose soil to properly form a bulb. If you are noticing more top growth and little to no bulb formation, it is likely due to a fertilizing/nutrient issue. While a soil test would allow you to know for certain, it may be that you have too much nitrogen and too little phosphorus. Lots of nitrogen will result in plenty of leafy growth but if your soil is lacking phosphorus, there will be poor root growth. I would add some more phosphorus, like bone meal, to the soil and give it some more time. Also, make sure the plants are adequately mulched to keep the soil cooler.