Oregon Grape Holly - Ask Extension
Oregon Grape Holly bushes (3) over 20 years old. Before cutting back this spring (after blossoming) they were nearly 6-feet high. One bush has col...
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Oregon Grape Holly #569981
Asked June 13, 2019, 11:33 AM EDT
Oregon Grape Holly bushes (3) over 20 years old. Before cutting back this spring (after blossoming) they were nearly 6-feet high. One bush has colored leaves; no sign of insects; just one bush. This bush does get the brunt of winter winds (have seen dried, dead leaves in the past). Is this something we need to be concerned about?
Jefferson County Colorado
Expert Response
Hello,
Thank you for your question, and I am sorry for the delay - I was out of the office unexpectedly.
From your photos, it appears that the Mahonia is suffering from leave scorch, a common occurrance with our cold windy winters. Some things that you can do to minimize this in the future:
References:
Mahonia aquifolium https://extension.illinois.edu/hortanswers/plantdetail.cfm?PlantID=350&PlantTypeID=8
Fall and Winter Watering https://extension.colostate.edu/docs/pubs/garden/07211.pdf
Pruning Evergreens http://cmg.colostate.edu/Gardennotes/617.pdf
Best regards,
Thank you for your question, and I am sorry for the delay - I was out of the office unexpectedly.
From your photos, it appears that the Mahonia is suffering from leave scorch, a common occurrance with our cold windy winters. Some things that you can do to minimize this in the future:
- Water in the fall and winter by hand, whenever there hasn't been precipitation for 3-4 weeks and morning temps are over 40F
- Do some structural pruning to remove about 1/4 of the internal stems to the ground. This will reduce competition among the branches for water, as well as open up the shrub to improve airflow in general.
References:
Mahonia aquifolium https://extension.illinois.edu/hortanswers/plantdetail.cfm?PlantID=350&PlantTypeID=8
Fall and Winter Watering https://extension.colostate.edu/docs/pubs/garden/07211.pdf
Pruning Evergreens http://cmg.colostate.edu/Gardennotes/617.pdf
Best regards,
