Hi,

Glad to see another fellow rock garden lover in the forum.

I have had scree type beds like those at the JC Raulston arboretum made from permatill for close to 10 years now. I also have a 40 by 60 bed on a sloping part of the garden in part sun. Many have been the successes and even more the failures. I hope my experience can be of help.

First of all, don't skimp on the depth of the bed. I made the mistake of trying to save money on the soil preparation by making my beds only 12 inches deep at first and our unforgiving red clay ate most of my plants in the first year or two. If you have a limited budget, you are better off using a smaller area and making sure your soil is at least 2 feet deep if you want to keep any kind of plant that requires good drainage. Sedums do not need this depth, but many companion plants do and you will eventually want to have others as they look better together with other little gems, bulbs, and dwarf shrubs.

Second, try to place your garden on a sloping piece of soil. Even a small grade in your soil will help tremendously during our periodic deluges in hurricane season and / or winter rains. Otherwise, water will collect under your plants at the interface with the clay soil and things will eventually rot due to capillary action of the soil sucking up the moisture.

Third, forget about fancy amending of the underlying clay. It is simply too expensive to do for any sizable garden like mine which has over 15 thousand sq ft of beds, 2000 of which is rock garden-type. I recently paid 100 dollars a cu yd for permatill and 24 dollars for good compost. At those prices it is simply not practical to amend and add what your soil needs IMHO unless you have access to farm manure and / or industrial quantities of amendments. Build up instead: I used brick pavers to define an area (no mortar), then piled it up 3' high at the middle and sloped it to the bricks. It compacts to 2' high after 2 years.

Fourth, the soil mix you use is less critical than you may think. The key to a good garden is drainage and the percent of the soil that is organic. I experimented with many mixes using ground bark, permatill, compost, rotted leaves, sand, gravel, turface, etc and they mostly all worked. You can find the recipes on google. If your bed is placed on a slope and the soil is built up sufficiently, they all work.

Fifth, I like permatill and turface for their ground-loosening properties. It makes a joy to rework your beds which I have had to do a couple of times in 10 years. Voles and moles don't seem to like permatill which is a bonus. Permatill also is attractive to my sense of what a rock garden moraine looks like to me.

Sixth, don't forget to add lime every year. You need it to keep the plants healthy. Use half the amount recommended in the bag of dolomitic lime and have a test done every 3 years to monitor PH.

Seventh, don't use pesticides, herbicides or other chemicals. My best results were obtained after I went chem free. Live with a few weeds, don't dead head, don't cut down spent foliage and a great community of predator insects will move in and control disease and pests, worms will thrive and the soil will improve over time.

Eight, feed the soil. Every 2 years, add a 1 inch layer of good compost around your plants after they show growth in spring. The soil will just keep getting better and better and diseases will be kept to a minimum. Either home made or purchased cured, aged compost is fine.

So to your original sedum question: use 2 feet deep beds, any good soil recipe with between 20 and 35 percent organic content (compost, leaves, rotted manure, etc), some permatill added (20 to 30 per cent has been good for me), and a sloping site and you can't fail. Start small and expand as your pocket book allows.

Best luck.
RJ in Raleigh

Thank you for the wealth of information. I appreciate the time you took to post it. I think I'll be off to a great start. I only have one more question. Google is killing me on the soil recipes. I had searched for them prior to posting and found either very specific recipes that required hard to find items or very general descriptions. Assuming a 30/30 mix of permatill and compost (I have bags and bags of black kow, mushroom compost, and humus left over from our raised vegetable bed which I have assumed would qualify) I'm wondering what would be better to add in that other 40%. I also have several bags of soil conditioner and a pile of topsoil at my disposal. The topsoil feels a little heavy but nothing like the clay of course. We do have easy access to river sand as well. We are lucky enough to have a large distributor of mulch/sand/gravel of varying sizes/topsoil/etc. within five miles of the house and their prices are reasonable. Our access to permatill isn't as great. It's like.. $12 for a 40lb bag which looks like approximately a little over 1/2 a cubic foot.

As far as failures go, my first two rock garden plants were sedum ogon and hens and chicks. I planted them directly in the clay and mulched them LOL. They are both still alive but happy about it? Not so much. My hens and chicks hasn't had any chicks in three years and it has done this really weird thing where it looks like one of those straw papers that someone dropped water on and the Ogon is just a sad and very small little patch that looks like it is being drawn in to the center of the earth. Oh well, live and learn. In my next episode.. fun with pond plants!

Oh boy, we could swap failure stories forever, could we not? But that is part of the game of plant love. We try to grow the impossible, and even the nominally easy and things don't go as planned. We learn something each time but that school of hard knocks sure has steep tuition fees. Take heart though that many of us just have an irrational impulse to persevere through drought and flood, cold and heat waves, plagues and bad soil. And over time we (mostly) get something we enjoy.

It took many tries to get my patch of lenten roses going for example. Now they are happily expanding on their own. I have never been able to get cyclamen to expand. But others have, including trilliums. And the stories go on and on.

These failures and successes are one of the key reasons to have lots of gardening friends and to be generous giving away plants. Friends can give you lots of advice that cost them plenty to obtain and when your beloved plants die, you may (hopefully) be able to get them back if one of your friends has a propagated piece of it around.

But enough philosophizing. To your question: the container gardening forum at gardenweb is full of recipes for good soil. I have found most of them work fine as long as you keep organic content below 40 per cent. More than that and the soil will literally disappear in front of you with age (it compacts to nothing as the plants and microbial life use it up). You need some of the soil to be inorganic so it will keep it's tilth/structure. Good loam is equal parts sand, silt and clay with 20 to 30 per cent organic content *which includes the worms, insects, roots and other microbes themselves*. All these measures are by volume.

For your specific situation, I would use 30 per cent permatill, 30 per cent whatever organic material you have (manure, compost, humus or a combo of all 3), and 40 per cent of your native soil or if it is too clay-heavy then purchase a couple of yards from a local landscape supply store. I use the one near us on Norwood or Triangle Landscape supplies or whoever is selling good grade stuff. Watch out for reclaimed materials from human waste sludge that some people add to raise organic content - it is glue like in behavior and I suspect it carries some pathogens. Buying stuff in bags is too expensive - you can get 27 cu ft in 1 cu yd - at 24 dollars/yd for good soil (no.3 landscape soil fines in my supplier's parlance) or less than 1 dollar a cu ft and it's already 1/3 inorganic (sand mostly.) It makes sense to buy in bulk. Plus you can get it delivered. The down side is you have to shovel it to where you need it.

I have had good luck using used up soil from repotting my containers, and from using old already-amended soil from my existing beds for the inorganic fraction. If I were pushed to buy stuff and I did not have anything handy near by, I'd probably use the "top soil" sold in bags at Lowe's and Home Depot for the inorganic component of my mix, with maybe 10 per cent sand added.

You may be getting the impression that these proportions are somehow scientific. Nothing could be further from the truth. Plants are very adaptable as long as they have proper air and moisture levels at the roots. They'll even grow in completely inorganic mixes like pure turface if you can control the watering and feed them liquid micronutrients. That's the same as static hydroponics. My point is, don't worry too much about getting these mixes right. You are not baking a cake, more like seasoning a stew. Done to taste, with attention to what you are growing and how it responds, and then feeding compost and lime as needed.

That is it. The rest is trial and error. If you have not gotten a hold of Elizabeth Lawrence's book "A Rock Garden in the South", go to your nearest library and borrow it. Also, the North American Rock Garden Society is a great resource as are the friendly folks at the local chapters. There's one here in the Triangle.

A final note: all these info applies to open garden beds which have an underlying stratum. Gardening in containers is a whole different ball game. For those I use 60 per cent fine ground pine bark, 20 per cent vermiculite and the rest compost with some plants receiving a little sand and or granite dust. Because of the physics of small enclosed spaces, potting soil needs to be very loose and full of air pockets while containing billions of micro pores that hold moisture and air simultaneously. Once used up (after 1 to 2 years) these mixes are great added to your garden beds but even the best garden soil will water log your plants in a container because of the suspended water table dynamics even if you use a wick. More on this in the container and bonsai garden forums if you want to learn more about it.

Part of the fun is figuring all the tricks out. I have been gardening since I was a boy with my grandma and I am still a newbie, learning stuff every day. Enjoy it.

RJ

Our soil is classified as Pac2 - Pacolet sandy clay loam and it is supposed to be well draining. Apparently it is also very acidic. Now, the raised beds were here when I moved in. The previous owners graded the property around the house (which included a gravel driveway) and piled the soil into an unfathomably huge flower bed. To give you an idea, we created a seating area in the middle of one end around a fire pit. So this is part surface layer, part subsoil, and more than likely part underlying material. I select a part of the bed to work in each year and turn the dirt with a forked spade (used to use a shovel until I bought my first forked spade), break it up a little by hand and pull out all the driveway gravel so that is no longer a component in over half of my bed and none of it that gets full sun. The clumps fall apart with just a little pressure when they are moist and I often find deposits of decomposing rock or pockets of a sandy material that could also be decomposing rock. The particles are gritty but don't feel quite like sand.

Anyway, thank you again for all of the valuable information. We have that plant swap on the 8th and while I would like to be able to have it complete (because I am a showoff) it is last on the priority list. When I get it installed I will definitely come back and let you know how things are going. Do you have a web site of your own?

Good luck with your project. Sounds like you are doing the right things already and are well on your way to a beautiful result.

Another piece of advice: avoid rototillers like the plague. They destroy the tilth of your soil and makes it compact. What you are doing with the fork is what I do as well. And building up is always better anyway. You are lucky if you have Pac2. It needs a little more organic material to retain water than clay but otherwise is good stuff. Keep adding rotted leaves and small pine bark nuggets to it over time as your mulch and you'll get lovely black soil in a few years once it mixes with the annual or biannual compost applications.

My web site was on geocities which is now defunct. What do you recommend for creating a new web page? I have lovely garden pictures to post right now.

RJ

I was given a tiller two years ago in gratitude for taking someone's dog to the vet when they couldn't afford it. I didn't expect anything in return and I really didn't want the tiller but that particular person brought it here and left it and would not take no for an answer. I guess some people can't possibly believe that a gardener couldn't use a tiller. It was a kind gesture though and I did use it once only to learn that it indeed did exacerbate my issues with the area I was working in. I gave it to my neighbors last Spring and in return they supplied us with some of the best veggies I have ever tasted.. all season. That probably paid for that old used tiller two or three times over so it all came back in the end. I guess even when you are not expecting it, it is nice when others insist that they show that your efforts are appreciated.

Anyway, I like doing it by hand anyway because it allows me to really see what is in the soil. I feel the texture on my hands, can get a close up view of the particulates, am less likely to miss rocks and weed roots, and I can see all the critters and gently move the ones I want to keep and toss the ones I don't care for.

I know it's really a no-no but I have been turning my hardwood mulch into the soil as it decomposes and it is already turning a brown-red and dark brown in some areas.

As far as a website goes, that depends on what type of site you want. For a blog site, Wordpress is getting a lot of mentions although I have never used it. I have a formal education in programming and web design so if I want something I usually either use open source and modify it to death or build something of my own. I tried Nucleus once and wasn't really all that impressed. All of my sites (as it were) are currently running on one core installation of drupal on hostgator. I'm not really what you call a dappler but that is generally all I have time to do so my web sites always stay in some form of disarray. I have designed one site five times but never added any content of value. Right now I am working on zone-7.org which is almost devoid of content but I am trying to add a little here and there when I have time. I can add bloggers but I like all the blogs to look like the rest of the site lol. If you just want a place to journal, it's ok though and you are more than welcome to sign up and I can put you on the blog group (we call them garden journals)

Anyway, hostgator has been reliable and the help friendly. I had a few issues in the very beginning but the service has gotten increasingly better through the years. If you want something professional, I would suggest getting a URL and some web space with them. I have a package that isn't the lowest tier and it's $14.95 a month and $15 a year for the URL. And of course, if this is something relatively new to you, I will be around if you have any questions or need any help setting something up.

So here is the progress as of yesterday. It's a mess, as is my yard. There is a raised bed to the left of the rock garden that has not been cultivated yet that I have allowed weeds to grow on to keep the soil from getting too dry and compact. We have mowed it with the rest of the lawn lol. I don't know how to do one project at a time so please don't laugh at my junk in the background. Since the photos are of a very uncultivated part of my yard, it is not representative of my gardens. Hah.. yes I am a little embarrassed about the yard junk. I have been meaning to take that variegated privet out but I have been lazy and haven't found anything to replace it with yet.

Anyway, we dug a trench the length and enough of the width to keep a sturdy foundation for the rocks. It is well below 18 inches from the top of the rocks to the bottom of the trench. The first picture is more representative of the slope than the second so while it looks more like we dug a basin, if the water table gets higher than the trench, it should drain just fine. We also put coarse gravel under the inside of the large rocks and are going to wash some sand in the cracks to create additional drainage through the cracks between the rocks. I know, it looks wholly unnatural at this point but the permatill alone has ended up costing $82 for that small area so this area is pretty much what the pocketbook allows at the moment.. with all of the other projects we have going on. We figured we would go ahead and move all of the boulders in one general location in hopes that when we expand, it'll save us a few steps later. We hope to have this filled, cleaned up, and planted by the end of the day.

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I still have some work to do around the bed. It has been threatening to rain all day but nothing quite yet. Think I am going to take that one red rock that looks like a dirt clod out and replace it and give the rocks a good scrubbing. The sun will eventually pretty much bleach the rest of them but that one is more decomposed than the rest so the mud is all up in the pores.

I'm kind of concerned about the consistency of the mix though. It feels somewhat muddy and after watering it down several hours ago, it is still wet. I mean, there is definitely grit in there but what isn't grit is sort of sticky feeling. Is this normal or is it something that will need to be addressed? And is it something that can wait a little over a week or do I need to pot those babies back up until I an get around to fixing it?

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Looking good. A suggestion would be to bury the rocks halfway in the soil to create pockets of cool earth for finicky plants. it is a technique often used for plants that like sun but also prefer cool feet in nature. With time it also gives the planting a nice patina, like the rocks have always been there. RJ

And Finally.. With exception of deciding what I want to plant the big bare spot in the front with, I am finished with this area for a while. I made sure to bury the bottoms of the rocks but I need to lift that cranberry bush and plant it somewhere else before I can build it up anymore.

That huge rock in the back was there when we moved in. I kind of hoped for something more natural looking but will settle for not having that big rock sitting there all by itself. I installed an access path along the back. The picture makes it look a little more lumpy than it really is. It's a little more obnoxious than I planned but once it is all planted and things fill in, I would like not to see it much at all.

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About the "sticky" feeling of the soil, part of that will go away when the micro flora/fauna of the soil develops. The soil will get tilth and the worms and insects in the soil will make it more sponge like, introducing billions of air pockets. When you put plants in now as a new bed, try using levelers sand or permatill or some other type of crushed stone (with a variety of particle sizes) around the crowns of the plants. A half an inch will suffice, to keep the crown from contacting the sticky soil. It's a neat trick an old gardener taught me. Also, resist the urge to over water. Do it once a week only, deeply. Your beds are looking good, now time and nature have to do the rest. RJ

Ah.. thanks again for your wise advice.

If you are talking about around and under the "leaves", I was worried about the stickiness when I put the plants in so I mixed some permatill, pea gravel, and a very (very) small amount of sifted pine bark fines to keep the leaves and crown free of muck.