Skyrocket Junipers Dying Inside after One Year

Question: Hi,

I had a massive landscaping project done last year. Including planting 7-8 skyrocket Junipers in my raised garden. The trees are connected to an irrigation line that has 3 drip emitters per tree. My sprinkler/watering schedule is as follows: M, W, F for 15 minutes at 3am, 15 minutes at 5am, and 15 minutes at 8pm. 

The trees have been doing well until recently. I noticed a brown color when I was sitting outside and pulled back some branches to find that each tree - although healthy and with new growth on the outside - is dead and brown inside. 

Is my watering schedule off? Do you have any other ideas? I had the landscaping company come back out as they are still under warranty (1 year), and according to the guy, the soil feels spot on - not too dry, not too wet. He also called the nursery who said don't worry about moving the mulch around (for what it's worth).

Any advice is appreciated. Thank you for reading.

responder: An Ask Extension Expert Replied August 16, 2024, 9:19 PM EDT
response: Brent,  Thank you for your pictures and questions.  We have a few questions for you before we diagnose your juniper issue.  1. Do you happen to have the tags for the trees? If so, please send us a picture.  2. How close are you to the one-year mark of planting?  3. What is the distance between the trees?  4. We noticed that they are planted in an elevated area. What type of medium was used to fill the area that they are planted (behind the retaining/hardscape wall)?   5. How many hours of direct sunlight do they get? 6. Did you fertilize them? If so with what and how much?  We will wait for your responses.   Kindly,  Kerry P Colorado Master Gardener, El Paso County

responder: The Question Asker Replied August 19, 2024, 9:07 AM EDT
response: Hi Kerry,Thanks for partnering with me on this!1. Oops I lied - they are Blue Point Junipers. I've attached pictures of the tag. 2. These were planted 8/1/23.3. They are planted 6' apart.4. The raised garden was in place when I bought the house in 2014. It was just regular fill dirt in there. I think the guys that added into the retaining wall added some more fill dirt, garden soil, and even a little compost if I recall correctly.5. They are planted against the southern property line, so they get most the day worth of direct sunlight. 10-12 hours if I had to guess ? 6. I have not fertilized them. Let me know if these answers are helpful or if you need more info on anything.BrentOn Fri, Aug 16, 2024, 7:19 PM Ask Extension <<personal data hidden>> wrote:

responder: An Ask Extension Expert Replied August 22, 2024, 2:06 PM EDT
response: Hi Brent!  Thanks for the additional information.  In looking at your photos I am thinking that your junipers are doing really well. In the late summer and into the fall evergreens of all types, including junipers will shed some interior needles. They are not able to photosynthesize effectively in the shade of the interior. Also, some needles are shed due to root loss during transplanting/establishing phase which is sometimes slow to appear in evergreens. I would keep an eye on the trees and if the browning becomes excessive to the exterior then there are other issues. New growth is excellent news! I do notice the one juniper at the end might have more browning near the bottom. You might check to see if the branch may have been damaged or broken during planting.  In additon, I appreciate the information on your watering schedule. The one unknown is how much water the emitters are allowing for each of these watering cycles. The emitters are usually 1/2 gallon/hour or 1 gallon/hour. Sometimes, they are marked on the small dripper parts. I would like to suggest that you try your irrigation system on manual with an emitter filling a small bucket to guage how much water your trees are actually getting.  The best advice is that a newly planted tree needs about 10 gallons per inch of trunk diameter at about 4ft above the ground per week. We do not want to overwater or underwater new trees. The emitters should also be spread out under the canopy of the trees to allow deep soaking so the roots spread deep and wide. As different types of soils hold water at different rates it is important to check the soil moisture under the trees regularly to see if the soil feels moist by digging a finger into the soil about an inch or two down.  Please also make sure that the mulch is not touching the base of the trunk. Keeping moisture off the bark of trees prevents rotting and fungal issues.  As the trees become more established you will be able to back off watering significantly.  I have attached some articles on related topics for your information.  Good luck and let us know if you have additional questions or concerns. Pam  Master Gardener El Paso County  https://agsci.oregonstate.edu/sites/agscid7/files/horticulture/osu-nursery-greenhouse-and-christmas-trees/onn011001.pdf https://yardandgarden.extension.iastate.edu/faq/inner-growth-my-arborvitae-turning-brown-problem https://csuhort.blogspot.com/2019/08/when-to-worry-about-evergreen-needle.html#:~:text=Premature%20needle%20drop%20in%20newly,dark%20green%20or%20blue%20hues.