Hey Bill,

Thanks for reaching out to the Colorado State University Extension Master Gardener Help Desk. Pinyon Pines are generally one of the most drought resistant evergreens so it does seem odd that it would be water stressed. CSU has more info about their hardiness here, but it seems like it would need minimal additional watering after it has been established. It could be something as simple as hot/ windy conditions mixed with the stress of getting established. A quick way to check is the screwdriver test. Push a medium sized screwdriver into the soil around your trees. If it goes in easy and come out clean, no watering is needed. If it goes in easy and comes out with mud or clay on it, you are most likely overwatering. If it doesn't go in at all, your tree probably needs a drink or your soil is super compacted. Based on the pictures, it doesn't seem to be too widespread, but I'll also include a fact sheet about common issues for Pinyons. 

I would also highly recommend mulching around the base of your trees. Just make sure the mulch isn't too thick over the new root ball and isn't touching the bark at the base of the tree. Either could lead to issues down the line. Here is another resource for mulching around new trees. 

Let us know if you have any other questions,

Brody K.

Colorado Master Gardener Apprentice

I would do the screwdriver test to see. It's hard to tell unless you are getting feedback and it is possible that you could be overwatering. Soil that isn't well draining plus 20 gallons of water a month may be causing some issues, but it's hard to tell without testing. If you are still not sure, they do sell moisture meters at garden centers and hardware stores and you could use those to get a more precise reading on the situation. 

Hello, 

Thank you for contacting us about your Pinyõn Pine watering questions. Pinyõn Pines are adapted to 9 to 14 inches of annual precipitation. As you mention, they are sensitive to overwatering and prefer a drier soil that drains well. If you have irrigation in the area that you have planted the trees, you might want to adjust the irrigation. 

In order to get the tree established, you mentioned that the trees were just planted, you will want to water more frequently. It is recommended to deep soak this tree as soon as it is planted and then weekly for the first year. A one-hour trickle that saturates the root is appropriate, each week. This amount should be adjusted based on your rainfall and irrigation. 

For mulch, you will want to keep the soil moist but let it dry between watering. Mulch will also help provide some buffer to freezing temperatures in the fall in order to prolong root development. Mulch should be 3-4 inches deep over the root area. 

https://planttalk.colostate.edu/topics/trees-shrubs-vines/1748-pinon/ 

Thank you, 

Rustie R. 

Colorado Master Gardener Apprentice