Raised Bed Soil Mix
We have one raised bed with soil in it! Granted, it is one of the small, square beds, but it’s a start! We’ll be filling the rest of the raised beds throughout the week.
This particular raised bed we got a donation from Gard’n’Wise to try one of their specially packaged raised bed soil mixes. We certainly don’t recommend that you HAVE to use a mix like this (we aren’t for the rest of them!). It will be fun to try it and see how it works though.
We put about 5 inches of woodchips in the bottom of the raised bed, because we didn’t have quite enough of the bagged soil mix to fill it completely full. They will break down over time and we can add more compost to the top to make up the difference.
Here you can see the list of ingredients in the mix. I don’t know how it holds water, so I’m not sure I agree with the bag’s recommendation as ideal for container gardening. Maybe it would work well for some of those big, Smart Pots that we tried a couple years ago. It is a mixture of topsoil, cotton burr compost, coconut coir, expanded shale (kind of like gravel, but popped like popcorn), humate, and several different types of ground rock/sand. I’ll be curious to see how it tests when we run the soil tests on it.
It actually looks kind of disgusting, if you think about it too much. The long fibers are most likely the coconut coir. You can also see a couple of the expanded shale rocks on the left side. Otherwise, just a nice, light (relatively) mix of soil. Definitely not as light as a normal soilless potting mix, but lighter than your average, mineral garden soil. I wonder if we will have trouble keeping it moist in a hot year?
There you have it! Our first filled raised bed. Now we are guaranteed at least one 16 sq. ft. area in which to garden this year.
Posted on May 7, 2012, in Around the Garden, Working in the Garden and tagged garden renovation, raised beds, soil. Bookmark the permalink. 4 Comments.
The Demo Garden Blog 
Hi Rebecca,
Hello again from the Monroe Mi Master Gardeners! That certainly is an interesting soil mix. We used 100% compost in our one raised beg veggie garden last year, with excellent results. Our demo bed was actually half of a bulk soybean bag placed up against a fence on the edge of our parking lot. One of our volunteers was using it to demonstrate what could be grown in a 3×3′ area in 10″ of soil, with only hand watering.
The mix you are using certainly has some southern components in the cotton burrs – and appears to be organic. It would be interesting to see the NPK results as well as pH. Our own compost has an ideal pH, but we have to amend the stuff (mainly oak leaf) we get from the City Works Dept with iron sulfate. And there is always the weeding that goes along with compost.
In the commercial greenhouse where we have an agricultural program for handicapped students, soil-less peat mixes are all we have. This is trucked in from Canada already pH corrected and has composted wood chips, sand and perlite added. It is a great growing medium for the bedding plants we produce, but it doesn’t hold water well enough for outside planters and pots. We have to add extra perlite and some form of gel humectant to make the mix suitable for these purposes.
What are you going to use in the remaining beds – which look gorgeous? You have some talented MGs to have built so many varied forms of planters over such terrible ground. We have a similar bed with an impervious construction left-over that is impossible to drive a stake into.
We can hardly wait to see what you are going to plant in your new beds!
Frank Deutsch
Monroe County Master Gardeners Association.
Yes, it will be interesting to see the NPK results on the raised bed mix. I would imagine they will have balanced the pH before bagging, but I could be wrong! We are doing a mix of compost and sand in the remaining raised beds. More on that later this week!
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