Dwarf Hinoki Cypress browning - Ask Extension
My 4 year old dwarf hinoki cypress appears to be turning brown, more than in the past. I know some browning is natural but this seems extreme. It get ...
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Dwarf Hinoki Cypress browning #674208
Asked August 07, 2020, 7:57 PM EDT
My 4 year old dwarf hinoki cypress appears to be turning brown, more than in the past. I know some browning is natural but this seems extreme. It get plenty of sun and I tried to keep it watered through this heat but possibly not enough. As you can see (pictures) it is against the brick house facing southwest and does get very hot. It does get some shade from a nearby tree. Suggestions?
Anne Arundel County Maryland
Expert Response
Unfortunately this Hinoki is already dead and may have been declining for some time as evergreens don't always show foliage symptoms of distress right away. Foliar browning for Hinoki is only natural when it occurs on the innermost part of the branches in small scattered locations, not when affecting branch tips or large sections such as this. (Some varieties bronze a bit in the winter, but such browning is less pronounced and temporary, limited to cold weather.)
Overly-wet soil or under-watering are suspect merely because Hinoki are not commonly affected by pest insects or diseases (aside from root rot) that would cause this degree of damage. Root loss from moisture issues will cause catastrophic death of foliage since the leaves have lost their supply of water. As the symptoms can be nearly identical, we cannot tell whether this plant received too much water or too little. Reflected heat from the wall may be stressing it, but being on a corner, it should have enough air circulation to not be too adversely affected. Likewise, the partial shade from the nearby tree should also help in regards to heat build-up.
Was any weed-killer used in the area? (We cannot tell if the planting beneath it are native Violets or perhaps Chameleon Plant (Houttuynia), a very invasive weed that often requires herbicide to control.) Otherwise, approximately one root zone soaking per week (in hot, dry weather) is about average for most landscape plants needing supplemental water. This depends on soil type, sun exposure, and drainage, so is only a guideline.
When you remove it, a look at the roots may indicate whether drought or root rot was a factor. Roots that are tough and intact likely got too dry at some point; roots that are mushier, easy to pull apart (the outer sheath will pull off of the stringy inner core), and might smell sour/musty likely stayed too wet at some point.
When you replant, you can add compost to the planting hole if the soil there is heavy and compacted. (If it is very sandy instead, compost will still be useful.) This improves drainage and helps to keep enough oxygen in the soil. Mix the two soil types together well when using amendments like this. The site is probably fine for a Hinoki if there is no other source of water (such as from a downspout drain) that keeps the soil wet. Situating the trunk of a new plant further from the wall would be beneficial, however, as this one is sited quite close and is more limited in root space.
Miri
Overly-wet soil or under-watering are suspect merely because Hinoki are not commonly affected by pest insects or diseases (aside from root rot) that would cause this degree of damage. Root loss from moisture issues will cause catastrophic death of foliage since the leaves have lost their supply of water. As the symptoms can be nearly identical, we cannot tell whether this plant received too much water or too little. Reflected heat from the wall may be stressing it, but being on a corner, it should have enough air circulation to not be too adversely affected. Likewise, the partial shade from the nearby tree should also help in regards to heat build-up.
Was any weed-killer used in the area? (We cannot tell if the planting beneath it are native Violets or perhaps Chameleon Plant (Houttuynia), a very invasive weed that often requires herbicide to control.) Otherwise, approximately one root zone soaking per week (in hot, dry weather) is about average for most landscape plants needing supplemental water. This depends on soil type, sun exposure, and drainage, so is only a guideline.
When you remove it, a look at the roots may indicate whether drought or root rot was a factor. Roots that are tough and intact likely got too dry at some point; roots that are mushier, easy to pull apart (the outer sheath will pull off of the stringy inner core), and might smell sour/musty likely stayed too wet at some point.
When you replant, you can add compost to the planting hole if the soil there is heavy and compacted. (If it is very sandy instead, compost will still be useful.) This improves drainage and helps to keep enough oxygen in the soil. Mix the two soil types together well when using amendments like this. The site is probably fine for a Hinoki if there is no other source of water (such as from a downspout drain) that keeps the soil wet. Situating the trunk of a new plant further from the wall would be beneficial, however, as this one is sited quite close and is more limited in root space.
Miri
