Phlox develops effectively without the addition of compost. Adding fertilizer and matured compost to your planting beds will give all the supplements significant in developing healthy plants. Utilizing chemical fertilizer won't make the plants spread any quicker. However, it might make the stems become leggy. This distracts energy that is required for development and disease opposition. In the fall, after cutting the stems, add a thick layer of fertilizer to secure the plants over the winter. It will also break down into supplements that they can absorb in the spring.