Q: My lawn company wants to do deep liquid fertilization on trees and shrubs. Is this a good time of year for this?
A: I am not a fan of deep root feeding if the injection is more than a few inches deep. Tree and shrub roots grow in the top twelve inches of soil. Putting fertilizer deeper than the roots makes no sense. Fertilizing should be done in response to a soil test. Has your company shown you the soil test they are basing their application on? Finally, fertilization is best done when the plants can use the nutrients, typically in spring or early summer. Fertilizer applied this late in the season could harm plants because they can’t absorb it readily and because drought has stressed them already. I found a good shrub fertilization summary at Home & Garden Information Center .