First, it helps to understand what we mean by clay soil. This type of soil has a structure made of very fine particles which sit closely together, meaning that air and water cannot easily move through the soil. This is what makes it ‘heavy’ and it can lead to poor drainage.
The biggest problem with clay soil is that it gets waterlogged. This can slow the growth of plants and even cause the roots to rot.
Clay soil is also heavy to dig and slow to warm up in spring. But these issues are outweighed by the potential clay soil has to be the foundation for a wide range of plants.