Hi Clay_Tucson,

It sounds like you're dealing with very compacted soil or a restrictive layer of some kind. The most common remedy is to dig one or two drainage 'chimneys' in the hole with the hope that it will break through the compaction and allow water to drain away from your trees roots.

The chimneys only need to be 3 or 4 inches in diameter. Don't place them under the rootball but rather off to one side.

Here's a link to a publication by the University of Arizona with a diagram.

Here is a link that might be useful: Planting Guidelines

Thanks aztreelvr, Yep, I came home from work today and the water STILL hasn't budged. How deep should the chimney's be? Will the roots still be able to penetrate that compact soil/restrictive layer? Do you recommend I go rent a jack hammer (I'd only do this if it was completely necessary for the health of the mesquite)? Thanks

That's pretty bad drainage. I would guess the issue is clay soil because caliche and/or hard pan wouldn't be responsible for keeping water in the hole. The water would still soak into the soil horizontally. So if you did have the chimneys it doesn't sound like the water would make it to them.

My personal thinking is you could dig a 10' wide hole and amend the soil but you'd still have a hole that didn't drain, nothing would really be solved. I'm a "it is what it is" kind of person. A mesquite has the best chance of finding its own way, they do this for a living. So I never add anything for natives, and a mesquite, hybrid or not, is close enough for me.

If it helps at all I grew thornless mesquite from seed this summer in a bucket with no drainage.

Tree roots will drown in soil that remains saturated so you'll need to fracture the restrictive layer, whether it's hardpan from compacted soil or caliche. How deep you dig your chimney may vary as caliche layers range in depth. Hopefully yours is shallow. I'd suggest you use a pick or long, heavy, metal rod to do this. The fact that there are trees growing in your neighborhood may be a good sign that you can dig through it without too much trouble.

Good luck.

Here is a link that might be useful: Managing caliche in home yards

Sounds good, I'll get my hands on one of those steel rods...Any idea how deep I should go (if it's not draining) before I say, "enough is enough" and just plant it? THANKS to both of you for your help.

I was watering my newly planted mesquites today and thinking about drainage. If you dig a hole and fill it with amended soil I can see the water soaking in fast and filling the hole with water. I don't amend soil for natives. So when I see standing water in the watering pan for a few hours the roots aren't actually in standing water. Soil of a uniform type can't really collect water in one spot subsurface.