It is okay for them to have food at this age, but not as much. Thye really should be utilizing their roots. If you straight folier feed to avoid the soil the roots cannot mature and grow. Underdeveloped root systems can cause the plant delays that are not recognizable right now, but may show up later in deminished bud development. These plants like to work, especially their roots and they will be lazy if you don't make the plant use em.
If they are showing signs of a deficiency at this time, like nitrogen, feed them 1/3 dose of veg/grow nutirents through the soil and the roots. Also, if you are sure your soil is not quality and is having a negative effect on the plants, then I reccomend transplanting to healthy soil. At this age it will never hurt to switch things up. GL