Yes, 80% of our clients grow in soil or soil-less mixes. The application mixing rates on our feeding calculator or on the brochures are designed so everything is mixed in water first but then fed to your plants whether in soil, water culture, true hydroponics etc. 

Typically, you want to feed the plants between 2-4 times a week depending on how large they are and how fast they are growing and you want the soil to be moist but not dripping out the bottom for more than a few seconds. Allow the soil to dry out in between feeds. 

We recommend 500 ml to 1 litre per 2 gal pot up to a 1-2 litres per 5 gal pot per feeding.