Answer: Beets are not keto, as they're too high in carbs.
Each serving of beets (1 cup) contains 9.2 g of net carbs. Unfortunately, that's a bit too high to be appropriate for the keto diet.
As a general rule, root vegetables rarely fit the keto diet. They're often too starchy, unlike leafy green veggies, which are mostly keto-friendly.
For a lower carb root vegetable, consider the radish. At only 2.1 g of net carbs per serving, radishes certainly leave beets in the dust.