Hi Eddie,

We see a few potential reasons causing the plants to struggle. Summer planting probably isn't one of them (well-trained landscapers install in summer all the time) but could exacerbate a plant's stress, particularly revolving around soil moisture.

The use of landscape fabric may hamper soil drying by trapping moisture during wet periods, similarly slow water percolation into the soil, and might decrease oxygen availability to plant roots, which is vital for their health. Eastern Arborvitae are not highly tolerant of saturated soil or poor drainage. Depending on how much water is being applied and how often, the plants might have been over- or under-watered. Ideally, you should feel the soil several inches deep and water only when the soil is becoming relatively dry to the touch at that depth. Tree and shrub monitoring is usually around six inches down, but for plants this young, you can probably start with checking four inches down. Soil type, site drainage, sun exposure, and other factors all influence how often watering will be needed, but as a very round guideline, slightly-older plants would probably need a thorough watering about once every week or so in hot, dry weather. New installations might need one or two waterings a week if the soil isn't compacted clay.

We suggest removing the landscape fabric and just using mulch alone to insulate soil, minimize erosion, and suppress weeds. Weeds can also become a problem on top of landscape fabric that has been in place awhile, so it's not actually a great long-term weed barrier for annual and perennial weeds. Fabric left in place long-term can also become intertwined with the roots of desirable plants, making its eventual removal necessary but difficult to impossible to do without damaging them.

The degree of dieback here suggests root death, either from poor root health at the start or due to soil moisture conditions. While you could trim out the brown growth and see how the plants fare (only if they have multiple main stems), it would be more practical to replace them. Exposure to dog urine may not be helping, but it's not the core issue here.

With all that said, it would be normal for a (healthy) plant to not show much above-ground growth after installation, since they devote energy to root establishment first so they can support more top growth. In general, with trees and shrubs at least, the older the plant installed, the longer this establishment phase takes. Shrubs this young should establish fairly quickly, but that could still take a year or more depending on how smoothly the process goes.

If you are wary about replanting now, you can wait until late summer to early autumn (around late August into September) to try again. Nurseries usually restock aggressively at that time, though the selection available might not compare to the peak of spring depending on what the wholesalers had in stock. Don't install evergreens too late in autumn because they need time to put on good root growth before dealing with winter freezes depriving them of moisture in the shallower soil layers.

Miri

Thank you once again for the detailed reply!

I cut off the brown branches up to the trunk and am going to water less. The soil has a fair amount of clay making it difficult to water so I have a soaker hose water it for 1 min every 10 minutes 4 times every 4 days. If it doesn't get better by next Spring I'll replant it.

Thanks again!

Clay soil watering is the same (in overall pattern) as that of other soil types, in that it should be soaked well when watering is needed but not watered at all when the monitoring point (a few inches down in this case) isn't dry enough when checked. You can't do much about rain, of course, so this will alter your monitoring schedule, but not all rain events soak the soil to the same degree, if at all (torrential rains tend to flow off the soil surface more than they soak in). The watering pattern you describe sounds both too frequent and not long enough in duration each session (though it's hard to tell how long it's running total each day, so it could be grossly over-watering).

The duration needed will depend on the volume of water applied and the water pressure, so you will need to experiment, but you want an irrigation session to soak in to the depth you're monitoring at least. As an example using an oscillating sprinkler, that could entail an hour or more of watering once every week or two. Drip irrigation usually takes as long or longer to deliver a comparable amount of water to a root zone. Instead of watering for that short of a period several times a day/week, try saturating the plant in one session (only on one day) and not watering again for around a week, or however long it takes to become relatively dry to the touch again at that 4-to-6-inch depth.

Miri

Oh ok! I like that plan. Next time I water I'll see how long it takes to become saturated 4-6" deep. The problem I run into is the water pools up in the ring I made around the tree so I have to let it deep in before watering it more.

Thanks again for the advice!

You're welcome.