Soil that has been under concrete (growing, fertilizer, manure, earthworms)

[Amontillado]

We had a concrete walkway broken up and removed (previous owners had put it in what we thought was the wrong place--we like our setup better) and the contractor who did the job told us "My experience is that you'll have a hard time getting anything to grow where the concrete used to be."

Well, we put in an azalea bush and it's not totally dead, but it's a pretty sad-looking specimen. We have other azaleas that are gorgeous this time of year, so we know it's not a general problem. The soil looks normal enough, but it seems as if the contractor was right. Is there a treatment we could be giving the soil to restore it? Now we're thinking maybe a statue would be the thing to place there, but unfortunately we agree that garden statues are 100% tacky.

[luv4horses]

When it rains, the leachate from concrete is at a very basic pH. Azaleas are acid loving plants and do not like a basic pH. You can amend the soil with supplements that acidify it, but you would have been better off mixing something like composted cow or horse manure in the soil down to at least 18 inches before installing the shrub. If your azalea is not growing, try digging it up as if to transplant it, then amend the soil properly and replant the azalea in the same spot. You can use about 50/50 compost and soil.

[TinaMcG]

The leachate from the comcrete was gone long ago, and it can only leach several inches in. I know this because I had this discussion with our Extension agent recently. The bigger problem is years of compaction and not being exposed to the elements. I'll bet the soil organisms are pretty few and far between, and that ecosystem in your soil is what it's all about.

Luv4horses is right about adding in lots of compost and other organic material. Give the area time to "stew". One season should do it, and don't be in a hurry to populate it. Just let it be after you have amended it. You can also do it more good by amending it again before next winter. Azaleas require really good soil, so I'm not surprised yours isn't doing too well.

[Bulldogdad]

Compaction

PH level (see above)

Hydrophobic soil

Lack of organic matter

Lack of natural flora and fauna (microbes/worms/etc)


1. Get a PH test add appropriate amendments to get as close to neutral as possible. You can then locally adjust the ph for the particular plant with certain fertilizers

2. Addition of organic compost during compaction break up and tilling. Could take a few years to rehabilitate depending on the type of soil

3.If your soil is hydrophobic lots of organic matter along with peralite and vermiculite can help until the soil is reconditioned.

[J&Em]

Originally Posted by Bulldogdad

Compaction

PH level (see above)

Hydrophobic soil

Lack of organic matter

Lack of natural flora and fauna (microbes/worms/etc)


1. Get a PH test add appropriate amendments to get as close to neutral as possible. You can then locally adjust the ph for the particular plant with certain fertilizers

2. Addition of organic compost during compaction break up and tilling. Could take a few years to rehabilitate depending on the type of soil

3.If your soil is hydrophobic lots of organic matter along with peralite and vermiculite can help until the soil is reconditioned.

I couldn't have said it better. That soil has been in a state where the only natural life in it was anearobic bacteria, if that much. It is a "dead soil" as far as plants go and will not support plant life which needs bacteria and fungi present for their roots to work.

As everyone has said COMPOST and lots of it. Then give it TIME until all the organisms that should be present return. If you are in a rush, add a lot of finished compost and qood quality topsoil. Mix all very well and let settle. Mix again in a month and do a soil test to see if something is still off with the pH, or other minerals. Once you have the soil test result you will know what else to add. Add additional compost and keep digging it in deeply. By fall it should be looking healthier and you should be seeing some earthworms populate the area. They will be a good indication that the soil will be healthy to support plants again.

It sounds like a long ordeal and wait but it will go quickly. When I moved into my current home I unearthed a ton of dead soil from where someone had covered the clay soil with solid plastic bags and then mulch. The smell was awful and it took a while to bring it back to life but I got my first plants in within 2 months and the rest the following year.

Before the azalea fully suffocates move it to anywhere else in the garden, even if a temporary home. where it has shading in the afternoon and plenty of water. You may need some fertilizer for acid loving plants, but only after it shows signs of recovery.

[TinaMcG]

Originally Posted by J&Em

Before the azalea fully suffocates move it to anywhere else in the garden, even if a temporary home. where it has shading in the afternoon and plenty of water. You may need some fertilizer for acid loving plants, but only after it shows signs of recovery.

I would put that azalea in a big container and baby the bejeebers out of it all summer, adding some of the compost that will be in its new planting bed. Then plant it in the ground in early September to give it a chance to establish before winter.

[Bulldogdad]

Originally Posted by TinaMcG

I would put that azalea in a big container and baby the bejeebers out of it all summer, adding some of the compost that will be in its new planting bed. Then plant it in the ground in early September to give it a chance to establish before winter.

Exactly. Power word of the day "Bejeebers"

[Bulldogdad]

Originally Posted by J&Em

I couldn't have said it better. That soil has been in a state where the only natural life in it was anearobic bacteria, if that much. It is a "dead soil" as far as plants go and will not support plant life which needs bacteria and fungi present for their roots to work.

As everyone has said COMPOST and lots of it. Then give it TIME until all the organisms that should be present return. If you are in a rush, add a lot of finished compost and qood quality topsoil. Mix all very well and let settle. Mix again in a month and do a soil test to see if something is still off with the pH, or other minerals. Once you have the soil test result you will know what else to add. Add additional compost and keep digging it in deeply. By fall it should be looking healthier and you should be seeing some earthworms populate the area. They will be a good indication that the soil will be healthy to support plants again.

It sounds like a long ordeal and wait but it will go quickly. When I moved into my current home I unearthed a ton of dead soil from where someone had covered the clay soil with solid plastic bags and then mulch. The smell was awful and it took a while to bring it back to life but I got my first plants in within 2 months and the rest the following year.

Before the azalea fully suffocates move it to anywhere else in the garden, even if a temporary home. where it has shading in the afternoon and plenty of water. You may need some fertilizer for acid loving plants, but only after it shows signs of recovery.

^^^Lots and lots of this

[Amontillado]

Thank you everyone for the useful replies. I'll try to put them into action.