Growing seedlings is a serious matter. It is necessary not only to prepare high-quality planting material and cultivate the soil, but also to calculate the optimal depth for sowing.
If the depth is chosen incorrectly, the seedlings may be weak or not appear at all.
The thing is that if the seeds are planted too deeply, they will simply experience a lack of oxygen, which means that they will no longer have the strength for normal growth.
Too shallow a planting depth is also not a guarantee of success. It should be taken into account that if the seeds were planted too shallowly, they will suffer from a lack of moisture. A thin layer of soil dries quickly, which means that you should not count on uniform moisture.
Optimal depth for seeds
Here you need to look at the size of the seed material. The larger it is, the deeper the hole should be.
It would be a good idea to take into account the soil characteristics. For example, if the soil is light, the seeds can be placed deeper.
The optimal depth for tomatoes is from 1 to 1.5 cm, as for peppers, you should not place the seeds deeper than 2 cm. If we are talking about cucumbers, then 1.5-2 cm is enough. If the seeds are very small, then you can not sprinkle them with soil.