Knowledgebase

Thuja fertilizer #778253

Asked November 22, 2021, 11:12 PM EST

I planted a row of 8' Thuja (the species which grow 10-15' wide and 30' high) in March at my place in Medford, Oregon Question #1 - I want quick growth. What should I use for fertilizer and when? Question #2 - is it better to water daily during the hot summer say 1 hour with two four gallon per hour drippers, or once a week for maybe 2-3 hrs with the same drippers? Question #3 - A few brown/dead braches are normal, correct? The plants look healthy after a hot summer, but there are a couple of small brown sub-branches per plant. No pattern/random Thanks!

Jackson County Oregon

Expert Response

First of all,we do not recommend that you fertilize any tree to achieve faster growth. What will happen is that you will likely lose the very shape (pointed and columnar) that you chose this plant for. You need to pay attention to the variety or cultivar that you have planted and then look up a good reference to see exactly what care it needs.  (For example, some of the larger varieties that nurseries sell need to be wired around to keep that conical shape.) All trees of this sort need fast-draining soils. Most thuja does well on regular, but moderate water during the growing season. A planting in my neighborhood is watered once a week in spring and summer for about an hour with a low circular sprinkler and is thriving. Once cooler weather and the rains set in, they are not watered at all. Too much water opens the way for root rots, rapid untamed growth, etc.As for the brown needles,we would suggest that you make a simple test to eliminate the possibility of spider mite, which is a common pest of thuja species. Taje a clean white piece of paper, place it under the affected branch, and shake the branch well. If spider mites are present, they will show up on the paper as small reddish dots.A well-stocked nursery will give you information on what sprays to use to eliminate the mites without harming the rest of the tree.Thuja needles also tend to brown in very cold weather. We recently had a sub-freezing night in the Medford area. If the brown branches are recent, cold might be the culprit. Remove the branches if you wish. Good luck with your new trees.

marjorie n. OSU Ext. Master Gardener Replied November 23, 2021, 7:22 PM EST

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