# Shallow depth plants



## Big John (Jan 4, 2008)

I have started to build platforms for my elevated garden railroad. I am adopting Richard Smith's system of making 2x4 frames covered with screen and landscape fabric. My table tops will have 2" of soil when I am done. I know Richard isn't overly concerned with real plants growing on the platforms but I want to have a lot of real plants around the tracks and structures. I have standardized on platforms that are 4' wide by 8' long. I have made 20 so far and have them stacked in the yard waiting to be installed on support legs. Is there a source where I can look up the type of plants that will thrive in soil that is only 2" deep? I know plants for rock gardens such as hens and chicks will be OK but I want to see what else is available. When my layout is finished I will have about 200' of table tops circling around the back yard. I will post a photo once I get them installed. Need to wait for the spring thaw to dig holes for the support legs.

John


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## Dougald (Jan 2, 2008)

John 

You do not state your climatic zone so is a bit hard to be specific. 

In general, rock garden plants and ground covers will grow in 2 inches of soil. But the problem really revolves around climate. If you are in a hot climate, keeping the soil moist in summer is a difficult issue - the water evaporates very quickly and plants, especially in full sun can be fried in a few hours. If you live, as I do, in a cold climate (bottom of Zone 4 though we often have Zone 3 like winters), winter dieback is severe. The cold gets under raised benches as there is no "insulation" underneath". My experience has been that only plants from Zone 2 or colder will live through the winter so I have moved to planting annuals in places on the raised portions of my railroad. 

Regards ... Doug


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## altterrain (Jan 2, 2008)

John,

Your best bet are small groundcover type sedums. They wil survive in two inches of soil if watered daily but nothing will thrive in soil that shallow especially with nothing underneath. Since you mentioned a spring thaw, I'm guessing you live in a cold winter part of the country. Winter root freeze would most likely kill anything you try to grow.

-Brian


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## Richard Smith (Jan 2, 2008)

John, 

One "possible" answer is to extend plastic or wood tubes clear to the ground through the hardware cloth and fabric at appropriate locations. Fill the lower extremities with rock for drainage and add soil on top. Use these just for the larger plants. I don't know how thick these planting tubes would have to be to insulate the roots. You'd have to experiment with that. 

Another option is to make shallow framed holes in the top of the benchwork with bottom support into which you can insert potted plants in the Spring. Fabric can be secured around the pot edge and covered with terrain to hide the pot edge/ This way the plants can be easily removed for pruning or change as well as brought inside for the Winter. A simple patch of hardware cloth and fabric can be used to cover the hole when the plant(s) is removed and simply covered with dirt. This would be the easiest method and was what I had originally planned to do for installing a few miniature trees. The well-tree'd surroundings on my property however eliminated the need to do this, which was good as space is limited on the benchwork. I do have 4 or 5 different mosses growing year around on the RR however of which three have been very successful thus far.

*One note: Be sure and use plenty of support beneath the benchwork. Soil can get plenty heavy especially when wet. I have legs every four feet beneath my benchwork with 1-1/2" of soil and without concern for snow load. I also make any hills hollow inside by using 1x2 framework, hardware cloth and fabric to reduce weight.*


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## Big John (Jan 4, 2008)

Richard, I want to thank you for the inspiration of making a raised bed railroad without the labor and expense of laying up a stone wall and hauling in tons and tons of dirt. I almost gave up because I knew I would never be able to maintain a railroad on ground level. After reading your construction artilce and seeing the pictures I jumped up and shouted EUREKA. Back to the plant problem. I live in central Delaware just outside the capital city of Dover. I moved here two years ago when I retired to be near my grandchildren. I am told this area is zone 7 to 7A. The two winters I spent here were very mild. Very few days below freezing. Never a real hard frost. Never more than a few inches of snow and that disapered after a few days. The railroad is on the north side of my lot directly behind my house. It is totally in the shade of the house all winter long and only has partial sun in the summer. I back up on an early growth forest with a lot of marsh land. In fact it is listed as a protected type 404 wetland, whatever that means. I could  install a drip irrigation system if that would be necessary to keep the plants alive. 

John


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## Big John (Jan 4, 2008)

I was concerned with the weight of wet soil on the platforms. I built my frames with cross pieces 12" on center and will have 4x4 legs at each corner and in the middle of the platforms. No more than four feet  without a leg support in any direction. Thought it would be easier to put in the extra effort now and not have to go back and reinforce things.

John


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## Richard Smith (Jan 2, 2008)

Good going John. It looks like you've already got it covered. You are so right about putting in the extra effort now. I only mentioned it "just in case".

One item of feedback. Bart Salmons encountered some warpage on a section of his raised benchwork on the side sill. We determined it was because he didn't install a combination arm rest and ballast rentention like I did. The 2x4 I install flatwise on top of the benchwork side sills creates a kind of "L" girder. Also it's important to allow the lumber to dry out a bit. This probably won't be a problem for you since you're building the sections well ahead of installing them.

I do hope you'll be able to post some photos when you begin construction as well as any feedback or problems you encounter. I am most interested in how well the system works out in different locations.


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## pdk (Jan 2, 2008)

Doug and Brian hit the nail on the head. Keeping most groundcovers alive in such shallow soil will be a daunting challenge.


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## pete (Jan 2, 2008)

I have been reading all of the posts because we are planting  dawrf alberta spruce in flower boxes. We planted them last fall and covered the out side of the flower boxes with styrofoam to help keep them from freezing. The flower boxs are sitting on the cement pad that covers our side yard. The whole train layout  uses about 170 ft of track. The track sits three inches off the cement .If this works ok then this summer we will put in more plants. The top of the flower box will be covered  and blended in to look like it is all part of the train layout so you will not see  any part of the flower box .The end result should look like the trees are sitting level with the rest of the train layout . Well that's the plan anyway/DesktopModules/NTForums/themes/mls/emoticons/hehe.gif


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## Big John (Jan 4, 2008)

I made a few pockets in my platform. I did it by screwing a few 2" wide strips of 1" treated lumber on the bottom of the 2x4 frame. Then I put the screen and landscape fabric on top of the support strips. That way I now have a 5" deep pocket of soil instead of the 1 1/2" that is normal. I hope these deeper pockets will permit standard type plants to survive. I will report results. I also plan to put in some dwarf alberta spruce suspended in three gallon buckets that I can remove in the fall and heel them in a mound for the winter. They will simulate a bonsai type plant but with a larger amount of soil. I will have a drip irrigation system giving them water in the summer. It can't hurt to try.

John


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## Michael Tollett (Jan 3, 2008)

From what I've read and your desires; it would be the same as container gardening. 
Try out HGTV and look into some container gardening topics, ideas, suggestions. 
If your framing is sturdy enough, you could consider building some planter boxes that attach underneath your frame where you want your plants, then you would build your containers to depth that you would want, or the depth that would increase the plants survival. 

Michael


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