Do dahlias have extensive root systems? Dahlias thrive in full sun and should be planted in full sun. A pH of around 6.5 should be present in the soil, yet they appear to flourish in my soil, which is thick clay with about one shovel depth of decent soil on top of it. If you are weeding or digging around the dahlia plants, be cautious since their roots are shallow.
How deep do you plant Dahlia bulbs?
Dahlias should only be buried to the point where the old stem is directly above the soil surface, unlike many other bulbs, which should be planted at a depth of 3-4 inches deep. Even though the tuberous root cluster should be buried, it is important to leave the old stem exposed since here is where the new root will develop.