Q.Hard Carrot Cores
I planted a 5 x 8 foot raised bed with carrots in early (Sept. ) fall. I rested one-eighth-inch plywood on the sides of the bed to shade the seed, and it came up well. I uncovered it as soon as the majority had germinated. I have harvested (thinned) all season. Recently, I pulled all of the rest, intending to blanch and freeze. Some of the larger tops had split carrots, and some of the carrots had hard cores. What am I doing wrong? I live in the Sacramento Valley in Davis.

Certified GKH Gardening Expert
This happens when the soil is not loose enough. I would guess that your soil is either clay heavy or rocky, which makes it hard for the roots to grow downward well. If your soil is clay, try amending it. This article will help with that: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-improve-clay-soil.htm
If your soil is rocky, it would be a good idea to create a root vegetable bed, where the rocks have been sifted out or where the soil has been replaced with clean topsoil.
This article may also help: https://www.gardeningknowhow.com/edible/vegetables/carrot/fix-deformed-carrots.htm