There are a few signs by which you can tell that a soil is rather unsuitable for growing your autoflower. If the autoflower soil is light and not dark brown, it most likely has insufficient nutrients and is therefore not suitable for growing. Furthermore, you can do a smell test. If the soil smells unpleasant, this can be an indication that the soil is too acidic and in this case you should rather not use it for your grow. Another indication for bad soil is to use your hand. Take some soil in your hand and form a ball. If the ball sticks together well and does not fall apart when squeezed gently, the soil is too heavy for growing autoflowering plants. Instead, the soil should be airy and fall apart easily when squeezed.