My carrots and radishes are going to seed before the vegetables have even started. My onions never came at all. I did soil testing at the start of the year and added mushroom manure prior to planting.
Your Radish, Carrots and Onions likely bolted due to heat. This is common in Radish, as they prefer cool weather to grow in. The onion and carrot is a bit more usual, though the heat can also trigger them to set seed.
There is nothing a gardener can do to control the weather, harvest the crop that you have now. Baby carrots are delicious and small onions are great to have in the kitchen.
You an search out bolt resistant seeds for next season.