Planting in compacted soil?

We took out our garage last summer, in part so I would have room to plant fruit trees (Asian plums!) in our urban backyard. The trees should arrive from Raintree next week.

As I’m sure you can imagine, the soil under the garage was pretty compacted. We have a lot of clay in our soil, but have had a lot of success with amending it for vegetable gardening with compost. So we tried to amend with plenty of compost where our garage had been, and planted white clover. I just dug an exploratory hole and found out that we now have really great soil for about 6-8 inches and compacted-looking clay under that.

Is there any way I can set my plums up for success in this situation? Appreciate any advice I can get!

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Lowe’s makes a soil amendment for clay soils. It says that specifically on the front It has what looks like some bark pieces mulch and compost Don’t have a photo handy. Price is reasonable. It helped me a lot. I mixed it 50/50.

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I did something similar, converting our compacted dirt-floor garage into a greenhouse. What’s worked for me is digging a much larger hole (both in depth and width) than normal for each tree. Then I mix that removed soil with a bit of compost/manure/sand (after breaking it up as much as I can), and fill the hole with that mixture, planting the tree a few inches higher than surrounding ground with a mound of the soil mixture around it to account for settling and help with drainage.

I was surprised how many tree roots I encountered in that process, so I am not too concerned about the trees getting rootbound in the hole as they grow, but it’s possible if your soil is more solid than mine that could become a concern.

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Soil Conditioner? I have an online friend that turned me onto it. Depending on your location its mostly fine fir bark mulch which is excellent for rooting cuttings. It was in stock last year at my lowes now i cant find it on the website.

I have solid clay with no soil at all. I used read haven rootstock and poncirus trifoliata and they grow like weeds in this clay.

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Along our driveway the soil was so compacted and poor on one side that I had a hard time digging in it even with a pick-axe. I’ve been layering it with arborist chips off and on for a hand-full of years now, but it wasn’t long before the soil started softening up. I can dig in it now with even just a hand spade.

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A lot depends on whether the subsoil can actually drain. Very few plants will do well if they have wet feet due to inadequate drainage. Compost can only do so much but does very little to address your underlying clay soil at deeper levels. Typically clays are good to build on due to favorable compaction, and quite often they form over time an underlying hardpan. Hard pans are just that and are very solid and hard to dig thru and can prevent drainage of the topsoil. Chances are the builder compacted the underlying soil before building the garage you removed.
You should first investigate your drainage by conducting a simple perc test. To do this dig a 2’deep hole, fill it with water and observe how quickly it drains. If you have excellent drainage the water should soak in within 2 hours. If it takes a day or more, then there is a need to determine why, before planting your trees. Sometimes a hardpan in clay soils can be penetrated allowing drainage to occur if it is shallow enough. In any event sometimes it’s essential to install a drainage trench with perf pipe to allow an area to freely drain. If this is necessary, it’s better to do it before you have trees involved. Heavy clay soils can be softened up if you dig your compost to deeper levels, but that may require tillers that can mix the clay with soil amendments. Clays soils can also be a source of improving soil fertility when compost is incorporated greatly improving the CEC (cation exchange capacity) of your soil.
Bottom line: do a perc test and make sure you have good drainage before planting.
Kent, wa