We have received multiple queries about dying Inkberry in recent years (as planting them has become more popular), and while we haven't reached a conclusive diagnosis and one diagnosis may not apply to all of them, we have a few theories. While this species is known to tolerate fairly wet soils in wild habitats, there may be some inconsistencies with garden soils, or perhaps differences in plant genetics between cultivars and wild plants, that make them much more susceptible to dieback in our home landscapes. Perhaps it's soil acidity level or the makeup of the microbial community in the soil within their root zones; we don't know for certain yet.

We do know that Inkberry is one of the holly species vulnerable to Black Root Rot (Thielaviopsis). Like most root rot pathogens, this is a naturally-occurring organism in our soils that can't practically be eradicated, but it won't necessarily attack and kill plant roots without the plant first being under stress and/or the environmental conditions being conducive to the fungus thriving. In this case, stronger soil acidity helps to weaken its virulence, and soils near home foundations often is closer to alkaline than hollies prefer. Soils that don't drain well can also allow this pathogen to persist and infect roots, since roots can be stressed by the reduced oxygen access from soggy conditions. Sometimes soils in foundation beds is more compacted than other parts of the yard, though this can be remedied somewhat by using organic matter like compost as a soil amendment to loosen its texture. The linked publication goes into more detail about this particular type of root rot. Fungicide use won't be effective after symptoms appear, nor would we recommend drenching the soil as a preventative attempt.

A laboratory soil test may help you determine if the soil is suitable for acid-loving plants like Inkberry or if acidity (pH) adjustment would benefit them. Or, perhaps a different evergreen less exacting in its soil requirements would be a better fit. We have few locally-native species that are evergreen, low-growing, and sun-loving, but species native a little to our south or which are non-native but non-invasive might be good alternatives. While soil testing doesn't screen for pathogens, it can also tell you if any particular nutrient levels are deficient and how organically-rich your soil presently is. (Organic matter content will be shown as a percentage. Surprisingly little is needed for good soil conditions.)

For future plantings, it's best to monitor the soil by touch before watering to avoid over-saturating roots. Feel the soil about six inches deep next to the root ball, and only water when it's becoming somewhat dry to the touch at that depth. While keeping a moisture-loving species wetter would hypothetically be not very risky, there are complicating circumstances that might increase its vulnerability to an array of root rot pathogens or other infections, so it's safer to avoid this extreme unless the plant is truly a wetland-type species. It's possible the more diverse genetics of non-cultivar Inkberry would be more adaptable, but in that case you'd lose-out on the more consistent features of cultivars like known mature height. (Pruning Inkberry down to size does not result in a good look over the long term because they don't fill back in nearly as well as other holly types or similar-statured evergreens like boxwood.)

If you are open to alternatives, we can suggest a few, but more information would be needed about the site conditions and your desired aesthetics. (How much of that strong summer sun does that are receive? Do deer visit? What's the maximum height/width, unpruned, that the space would accommodate? Do you want the plant to be evergreen?)

Miri