What is a seedbed?
A seedbed is a seedbed. Whether in an indoor or outdoor container, in the greenhouse or in the open ground. It is usually used for flowers, but can also serve for herbs and vegetables.
The intention is to plant the plants elsewhere later. A piece of soil (or a container) is prepared with soil that is rather loose and fine in structure. The feed in this soil is just enough for the seed to germinate and make a few first leaves. Not too nutritious.
The loose, fine structure is needed because you have to move the little plants later to their forthcoming permanent place in your garden, planter or larger pot. The roots of those little seedlings are very fragile. In loose soil, the carrots cannot grasp tightly. That makes it very easy to take the plants out of the ground gently. When the seedling grows and has about 4 real petals (which does not include the germ petals), then it's time to take the cutie out of the seedbed and transplant.
You can make your own sowing and soil by mixing some potting soil with some crusher sand (for sale at the hardware store), a little rock flour (don't have to) some vermiculite (keeps the moisture and is available for sale at the garden center) and finally perlite (makes the earth very airy and is also available for sale at the garden center) garden centre).
Can you also sow without first preparing a seedbed?