To be honest, I’m amazed they look as good as they do. I'm astonished a nursery would think it a good idea to transplant trees that big in full leaf in mid summer. And they should not have amended the soil. All you can do is water like crazy and cross your fingers. Do not wait for the soil to dry out. Daily would not hurt. The larger the tree the more water they need and the more likely they are to suffer on transplanting. If you buy more trees in future you would do better to buy them much smaller and to plant when they are dormant.

If you can post pix of the base of the trees we can see if they have been planted correctly.

And I would counter that drip is not necessarily the "best" option. Any type of low emission irrigation will work equally as well - a garden hose on a slow trickle, a soaker hose or drip, provided there are enough emitters utilized and the watering duration is long enough. You just need a slow delivery of water sufficient to reach root depth.

How often and for how long will depend entirely on your soil conditions and weather. The rule of thumb is 1.5 - 2 inches of water per week for new plantings and best delivered all at once but again, that depends entirely on local soil and weather condition. Or testing that the soil at root depth (base of the rootball) remains consistently moist - not wet

welcome to the forums..

where are you.. big city name .. z6 is about half the US and VERY divergent .

what are the night temps ....

NEVER water a transplanted tree with drip irrigation.. unless you are going to leave that zone on for 6 to 8 hours ...if you mean you hand grip has a drip setting.. well i just dont know what that means ;...

trust your seller.. i presume he has a vested interest due to his warranty.. so. do what he told you ... period ..

you screwed yourself all up.. when you went the WWW and got conflicting info.. that frankly has nothing to do with your trees.. in your yard.. planted by that dude.. so what good did it do you other than stressing the beegeebees out of you???

based on what i figure you invested .. would you consider tree gators ... ask your seller what he thinks ..

ken

https://duckduckgo.com/?t=ffcm&q=tree+gators&iax=images&ia=images

Something I didn't see in the opening post was whether the crew removed burlap from the root balls when planting. That's important, because leaving on the burlap (especially if it's synthetic or treated) prevents or inhibits root spread into the surrounding soil, leaving trees vulnerable to soil moisture fluctuations and making them unstable (I have a vivid memory of seeing the aftermath of a thunderstorm with high winds on a neighbor's property. Two maples planted on his front lawn were completely blown over, even though they'd been there for a few years. The burlap was intact around the root balls).

"Today, I dug down to the edge of the root balls approximately 6 inches and noticed the soil is moist, but not wet. I scooped up a bit of soil and balled it in my hand. When I pulled up the amended soil, it crumbled and didn't stay formed. But when I pulled up soil with clay, the clay stayed densely packed in a ball."

You did well to check soil moisture at root level - a much better way of regulating watering than following a set schedule, which does not take into account rainfall and other climatic variables, as well as soil conditions. As long as the soil at that level is remaining moist (not soggy) between waterings, you should be in good shape.

As for amending soil in tree planting holes, there are different schools of thought about that, but many experts think it's fine to amend to a mild degree, especially if the surrounding soil is problematic. You just don't want to have excellent tilth in the planting hole and hard-packed clay adjacent to it, which could lead to puddling of water in the hole and roots not spreading out into adjacent earth like they should.