If the trees are in containers I'd keep them there until fall or next spring when they stand a much better chance of surviving, whatever the soil conditions. Planting in full growth in hot weather is always going to be fraught even in perfect soil.

Was this agricultural land before your house was built? I'm wondering if you've hit the 'hard pan', which can occur naturally but also results from years of ploughing.

Floral, I’m very sorry for the late reply. I’m catching up on GW today.

It was not agricultural. I believe much of this clay was brought in during the current construction. There was an existing building which was torn down, but the footprints between old and new are not exact.

We have been having very cool, cloudy, moist weather for three weeks! It’s been amazing. I’m considering holding them until next spring, but only if I can find a bigger pot to put them in. I’ve been delaying planting them only due to fear of this clay. It’s been amazing weather, and I hate that I missed it.

I did return the weeping cherry. Less than three weeks after I bought it the leaves on one branch began to darken and die, and then it spread to the next branch. I purchased it five weeks ago and the nursery was reluctant to take it back, which means I’ve also found a nursery which won’t get as much patronage from me in the future. Comparatively, another semi-local nursery, a bit more expensive, proudly told me their 1-year guarantee and provided literature when I purchased a tree-form Japanese Willow.

Do you have any suggestions on what to do when I do plant them in this clay, be it this year or next? I’m still more than apprehensive! I know for the DW crabapple I’m going to try to build up the loam/compost/peat so it sits more on than in the clay layer.

" I believe much of this clay was brought in during the current construction. "

This is pretty unlikely. New soil is rarely brought in for construction - rather, existing topsoil is scraped off and hauled away. Even if soil was imported for some reason, it would be fill dirt and not just clay. It is far more likley that the clay is just the composition of the subsoil and tilling has just aggravated the condition (tilling is the usual reason hardpan forms in the first place).

When working with a slow draining, clay based soil, you want to plant high in either a raised bed, a berm or by individually siting plants with at least half the rootball above grade, then mounding good soil up to the top of the rootball. Never amend a planting hole in clay! Instead, do as previously described and save any needed amendments to be used as a mulch or topdressing only.

You might also want to look into Permatill. I know that Tony Avent uses it in his remarkable Botanical Gardens.

with bad draining clay ... you plant high... which allows the plants to put their roots down into the clay.. without you drowning them ... until fully established ..

congrats is perc'ing to find out this future problem...

plant half the pot or BB in the ground.. and half above.. and then mound above the soil line with a good draining soil ..

clay is a very good growing medium... as evidenced by the fact that EVERY ball and burlap is made of clay.. sand doesnt work.. trust me on that...

but the growers have decades of dealing with clay.. and it doesnt involve digging cauldron like holes and amending the soil... i give you props for trying to do a whole planting bed.. but as you found.. the tiller has limits....

im sorry.. i cant find the right term.. to link you to a good reference ...

btw.. july is not really tree planting time.. unless done professionally. and with large warranties ... you might be best off.. collecting your material.. and planting in the next proper planting season.. which for you is around mid sept... when days are warms.. but no

nights are cool.. less stress on the person planting.. and the tree..and in fact.. the best time to plant.. would be when the leaves turn color.. and dormancy is approaching ... the tree will have two root growing season... before the heat of next summer.. if maine really gets that hot anyway.. lol ... refer to the link for general tree and shrub planting... proper timing is section one.

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

Hey @deanna in ME Barely zone 6a, more like 5b I second and third what ken and 'gg' have written ie plant high. I have taken this advice for the past several years for shrubs, trees and even perennials with great success i.e. much less loss of life from year to year. (But still my partner comments as I am planting the plant in question that isn't in the hole properly)

“perfect soil for building a pond.” Oh, rober, you are on to something. Husband would love a pond but would do 0% to maintain, so our ideal pond site is a dream only. You are right, though.

Your responses are a HUGE help. I had refilled all planting holes with the original clay chunks and matter up to the clay line and then planted above that creating the smallest of incline where required to reach the top of the rootball. There is likely to be some settling since I had disturbed the clay, but if half -in/half-out works, then my holes should be good! For all subsequent bushes I did keep new holes above the clay and build very slight slopes of soil/compost/peat to reach the top of the root ball. Based on your responses, that should work.

Also, I traded in some bushes for Japanese Willow ’Hakuro Nishiki’. It is supposed to handle standing water (like from the clay) well, and it actually coordinated with the building wonderfully.

I’ve added enough extra stuff to have probably 8” of soil. everything is going in well so far.

I am going to pot up the trees in larger pots now and wait to plant them until I know I can keep them above grade on the slope and have the better amended soil stay put and not wash away.

Ken, the only reason I would plant now is because we are having a loooooong stretch of unseasonably cool and moist weather. We are on our fourth week of temps in the 60s, continually coudly days, and gentle rainshowers periodically. It’s really quite amazing gardening weather! I have finished all but a few minor things for now. I don’t want to push my luck. I’ve actually been dividing stuff and it’s had such great weather to establish. Fingers crossed that we don’t transition immediately into 90 degree and dry days next week!

Thank you, thank you for your comments!