What Is Wrong With My Japanese Red Pine Shrub, And What Can I Do To Address The Problem?

Question

Purchased and planted two japanese red pine shruba in late 3/20, along two dwarf mogo pines. The two mugo pines and one of the two red pines have taken hold and are a verdant, dark green in color; but the largest of the two red pines is laboring (yellowing out with some brown spots). In the attached photo, you can see the two red pines — with the one on the left taking hold and the one on the right in trouble. All four shrubs are planted in similar soil and environment — a back yard of crushed rock which gets plenty of sun, in Sedona, AZ. Checked with the nursery where I bought the plants, and they first surmised that I had not given the plant enough water and then that the laboring shrub had been over watered! How do I check for over or under watering?? Thanks.

Answer 1

I would suspect overwatering before underwatering. Unfortunately, with the soil covered in rock it will be hard to tell when it needs water, visually. You will need to check with a meter. This article will help:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm