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Arborvitae Thinning at the Bottom #925671

Asked March 09, 2026, 10:43 AM EDT

Hi, I noticed one of our Arborvitae trees getting quite thin at the bottom. The one next to it looks like it's going that direction too. What could that be and is there something I can do? Thank you, Kim

Kalamazoo County Michigan

Expert Response

Hello!

Thinning at the bottom is often due to arborvitae not receiving enough sunlight at the bottom when the tree is pruned in an egg shape (longer branches in the middle shade out the bottom branches, which then die off). Pruning arborvitae in a pyramid shape prevents that problem. Other causes of browning at bottom include waterlogged soil, too-dry soil, and road salt. The photos you attached do not show any browning or thinning at tips or close to the trunk through the tree, so there's no reason to suspect fungus or pests, especially in this cold season; also, the thinning is not at deer-browsing height.

While you can't regrow the branches that dropped, regular adequate watering through the growing season and pruning in a shape that allows sunlight to the lowest branches is a good practice with arborvitae.

 

Thank you for your question!  Replied March 09, 2026, 8:58 PM EDT
Thanks for your time and reply.  I appreciate it. I'm glad to hear that you don't suspect fungus or pests.  We don't see any deer around our neighborhood.  

We've never pruned the trees.  They've just grown in that shape so I'm not sure how we'd be able to prune in a pyramid shape because the bottom has never been very wide.  I suppose with the weather the way it's been the problem could be the fact that it's water logged. So much snow that melted and then a lot of rain. That part of the yard is at the bottom of a slope.  In that case, I'd be hesitant to water too much during the growing season. Any further advice would be appreciated.

Kind regards,
Kim

On Mon, Mar 9, 2026 at 8:58 PM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied March 09, 2026, 9:20 PM EDT

Hello there!

If we talk about watering, it may still be necessary to water during the growing season, based on how much rainfall we get naturally. In a drought, the shrubs will still need moisture. Of course, if the soil is waterlogged now, no purpose in watering. 


Thank you for your question!  Replied March 12, 2026, 8:33 AM EDT

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