Although I am a peat-moss nut, I WOULD NOT use it if you have yearly rainfall of over 40" like mine. Peatmoss in wet clay is like making mud pie, it holds water even more.

Before the builder put topsoil, I already removed at least 20 wheel barrows of rocks. Twelve years later, when I dug holes to plant roses, water would not drain fast enough. I kept digging bigger 3' x 3' and removed a bunch of grapefruit sized stones - then it finally drained, and my roses are OK.

It's not gravel that blocks drainage, it's the melon size stones. I planted a white pine over gravel (on top on electrical lines, ComEd guy said OK) - it was great.

If your climate is dry, you can add peat moss to the hole to fish out more blocking stones. Peat moss loosens up the bottom clay, so the stones pop out. If you mix 1" to 2" of peatmoss to 6" of topsoil, it will lower your pH by 1 point. If you soil is too acidic, then use coarse builder's sand, or paver's sand (NOT fine playsand), to loosen up the sticky clay.

It's best to get a pH kit first before you use peat moss. The soil test (nitrogen, phosphorus, potassium) kit from Lowe's does not have accurate pH test, so I would buy a super-accurate pH test elsewhere.

Expanded shale or other amendment really won't help unless you raise the bed. Ultimately drainage has to pass through the subsoil that you have. If the subsoil doesn't drain, soil above it can't drain regardless of its texture. Also a french drain doesn't help unless it runs downhill to an outlet. However, if you raise the bed 6", that layer will drain, and most of a rose's feeder roots are in the top 6".

You asked about expanded shale. Expanded aggregate materials are used in lightweight concrete mixes and in the construction of golf greens and athletic fields. They hold air and nutrients, and a soil mixture of > 75% aggregate will drain fast. The best for soil is not shale, but expanded fired clay particles. Expanded clay has a suitable pH and holds plant nutrients in suitable balance. The largest brand is Turface. It comes in various sizes and a fine grade is best for soil. It is said to be an ideal base for potting soil. Smaller quantities of expanded aggregate may be sold as aquarium soil.

I am going for an all of the above approach. I will put in a french drain, with the grade of the drain sloping away from the bed. I had tried this in my old house with similar issues and it did work. I have some homemade compost that will go in the bed, along with a modest amount of peat moss. Finally I will try for a slightly raised bed. Wish me luck!! And thanks.

I agree that raised beds are the immediate solution. Then add lots of mulch (at least 3 inches, but do not let it touch the base of the canes) one or two times a year. The mulch will degrade into soil, the rose big roots will make it down into the real clay soil, and eventually you will have better soil. My father-in-law put in 10 large raised beds at his house because of the same problem, and 40 years later the garden had good soil

However, you will be able to plant immediately in the raised beds - you do not have to wait 40 years!

I am lucky in that my garden was started in an area with almost solid clay, but that was 106 years ago, and now it is all clay based loam down to about 12-18 inches. There are still some spots at the corner of the house that have never been planted, and you can make clay dishes out of the soil!

Jackie

Clay isn't a terrible thing to start with, some of the best soils are clay based. It's a ton of work to dig out >2 feet deep of clay, so a reasonable compromise is to raise the bed and just add a garden center's "top soil" which is usually pretty sandy with a bit of organic material. I did that which worked out great, I pulled all the rocks up to 2 feet down and made a raised bed with the rocks (there were a lot).

I put a bunch of peat moss which helped break up the clay, some lime to off set the peat, some bags of manure, and bags of mulch. The mulch gives it a long term break down of nutrients, but takes away some nitrogen in the breaking down, but it's easy to add some general purpose fertilizer to the mix while you're at it.

I just don't trust these fancy materials, expanded shale I believe is like vermiculite, I don't know how long term that would hold up. Baked clay, well, maybe that will hold up, but realistically when people talk about adding soil improving materials to replace the base, for example sand, you have to be like >50% sand content to really start draining well, adding a couple bags won't make a dent in your problem. So the only realistic thing for mere mortals is to accept your base and ammend it (which still is a lot of work).

I'm not for organics in the yuppy sense of the word, but as far as creating good soil, I'm all about organic matter. It really is the only feasible way to improve your soil unless you're going to rent a bob cat to remove and replace soil.

Just don't expect throwing a couple bags of miracle material will fix the problem, you need A LOT to make any difference. Organic material you can get away with less, but basically the more you can work in at the outset the better you'll be.

Here are some pictures from my renovation of my back yard.

Garden Renovation

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Vermiculite will compress over time and lose its loft, so it's not recommended for use in garden soil.

However, expanded clay, shale, and slate are permanent materials. They differ from sand in that they are porous and able to hold water and air in their internal spaces. Note that expanded clay such as Turface is different from cat litter, which is cooked at a lower temperature and will soften into regular sticky clay after long wetting. Expanded slate and shale have the potential to create some odd soil chemistry, so expanded clay is the safer choice. However, Texas A&M uses expanded shale successfully in their Earthkind planting program. They till in 3" of shale and 3" of compost to create raised beds.

It's surprising but true that adding sand less than 70% just makes the soil heavier and less fertile.

Thanks for all the good advice. I tried to dig and even took a stab at a French Drain. But then it rained and I found the water pooled just as bad.
So back to the drawing board. I am making a raised bed using whatever I can get my hands on: peat moss, compost, rotted cow manure, some sand and wood chips. I am telling myself it will be fantastic and that the roses will love it. I hope that is the case and I will update when it is all done.
What lime do you use? Is it the granulated limestone sold at the garden centers? Thanks. Paul

Paul,

Don't add lime unless you have tested the pH at 5.8 or below or you are adding lots of peat. Ground limestone is preferred--sometimes it is pelletized for use in spreaders, which is OK. Dolomite limestone contains 2:1 calcium to magnesium. This is good if your soil is low in Mg, bad if it is high.

As I said in an earlier post, french drains do no good unless they lead downhill to an outlet. Otherwise you are just creating an underground pool.

From online Texas A & M article:

Dr. George also remarked:

"Based on a two-year research study and six years of field trials, I feel that expanded shale will open up and aerate heavy, sticky clay soils faster than any material that I have ever tested. Due to its porous nature, it provides aeration from within the shale particles and, in poorly aerated clay soils, resulted in a more extensive and healthier root system than did other treatments being tested....Even though I dearly love finished, plant-based compost, if I were limited to only one application of one soil amendment with which to open up heavy clay soils, I would take expanded shale and never look back!"

Here is a link that might be useful: full article from Texas A &M

OK thanks. I am going to find some expanded shale. I found some on the internet in 40 lb bags but the shipping cost was high. I hope I can find some locally, How many lb per sq ft is recommended?

From the Texas A & M article:

"For flower beds with sticky or gumbo-type soil, Dr. Steve George of the Texas Cooperative Extension recommends putting down 3 inches of expanded shale on top of the area, and tilling it in six to eight inches deep. Also add 3 inches of finished, plant-based compost as well, which results in a 6-inch raised bed. Crown the bed to further improve water drainage."

I don't know where you live, but expanded shale is found at garden centers and bulk soil yards here in the Houston area. I have never seen it at Home Depot or Lowes near my home. I think that expanded shale can be found throughout much of Texas, but if you live in another state it may not be available.

Here is a handy converter from a Garden Center in Dallas, TX that could be useful for more than just expanded shale.

Here is a link that might be useful: Garden Measurements and Conversions

The raised beds will certainly help with the drainage issues as excess water will flow outside of the beds, but there is one thing that has not been mentioned above that I would highly recommend and that is to perk test your rose holes before you plant the rose.

If your rose hole doesn't drain completely at least overnight, you are not done with that rose hole. Looking back, I would have done a lot of things differently, but I did perk test my rose holes and found that some of them still needed extra work to get good drainage.

Now, I am working at fixing some of my mistakes, but I don't have to worry about drainage even with the heavy winter rains we get in my area.

Smiles,
Lyn

After a lot of searching on the internet, I came across a company that distributes expanded shale. It is BWI companies. They are located in the south and southeastern states and supply to nurseries and garden centers. My local nursery in Arkansas had not heard of the product but is able to order it in for me. I will build up the bed with peat moss, compost and shale. The bed fails the perk test, but I hope I can help that with a raised bed. Anyway, I appreciate all your thoughtful responses. It is fantastic to be able to solve a problem like this by posting a question.

We will soon have another crop of leaves for grinding up to mix with grass clippings to make compost--works great for making raised beds!

We were in the same situation--heavy clay subsoil, rocks and debris that had been extensively driven on by construction vehicles when the house was built.

An alternative to the French drain that we used to fix the drainage issue in our raised bed that would not drain properly there was 'dry wells': dig a 6-12 inch hole deep (3-4 feet). Line with landscape fabric as you can to prevent soil from refilling it and fill the hole with stones or large gravel. It gives the water a place to go to get below the packed subsoil layer. This should work as long as the soil compaction is the main reason for poor drainage. If it's a low-lying area this wouldn't solve things.

We put three of these in, raised the bed by about 12" and filled the bed to about 2 feet with good soil and have had great success with roses there ever since.

stlgal, what a good idea! I will do that as well as everything suggested. My roses will be in rose heaven. :)

We live in Oklahoma, and have clay soil. My solution has been to take a pick ax, dig down at least a foot, remove the clay, then before putting in anything, take that axe and work up the remaining clay. Once the remaining clay has been stabbed and torn, put in some top toil or compost. THis is for drainage, and the added soil will never never combine with the clay.

Once you have this part of the bed prepared, you have a hole that is at least 12 inches deep. Put in good top soil with some compost mixed in it. (Pure compost will create a swimming pool, and kill any plants.)

Once you have filled the hole, water it, stomp on it, then continue filling higher and higher. Put in some plastic or metal around the sides of the bed that will hold the soil, and continue building it up. Again water and stomp.

When you plant your roses, make them very very high. THey will begin to sink, but start with them high. You are planting in a modified raised bed.

Little by little as time goes by, you will know when to add compost, and you will watch the drainage.

If you need to display one rose, follow this process, and pretend that you are preparing a bed for 5 roses.

The clay will begin mixing in with the top soil ----- never. As least never in the years we have been here, and that is since 1979. Peat moss will become as dry as a brick, and also will not mix well. This may not be true if you live in a wet area, but in Oklahoma, I don't use peat moss.

If what I have written will not work for you, you might try putting in small rock under the 12 inches you have dug.

Once you have prepared you bed and roses, you would need a good amount of mulch to also protect your plants.

Be sure to be scientific with your watering, and I think you will be fine. Scientific with watering means that you should find an area to dig where there are not roses, and watch from time to time what the water effect is in that area.

The clay that you remove can be a good product to use to border your beds.

I hope this helps,
Sammy