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Alabama Gardening

What to use in place of pumice and decomposed granite?

swiss_chard_fanatic

8 years ago

last modified: 8 years ago

I'm about to embark on my first raised bed garden and I was going to use jonhughes(So.Oregon)'s mix as follows (because the pictures of his gardens just blows me away; wow):

45% Clayish soil
25% Compost
10% Pumice
20% Decomposed Granite

But local plant nurseries, hardware stores, and landscape supply companies don't seem to carry pumice or decomposed granite, calling them "northern" ingredients. Ok, so what can I use in place of them that will function the same?

I was told I could use perlite in place of pumice and "crush and lime" (I've never heard of crush and lime) in place of decomposed granite. Is this correct advice? My understanding was that pumice was superior to perlite; is that true?

I have very heavy, dense clay soil on my property and need to make it more airy...

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Comments (3)

swiss_chard_fanatic
Original Author
8 years ago
It seems you just can't go wrong with pumice, which is why I was so sold on it. I read this about it on another website:

"Pumice is an excellent soil conditioner, as it is highly porous,
giving it excellent water and air holding properties. Advantages of
using pumice in potting media and garden soils include:

—the porous nature of pumice allows it to hold vital nutrients in
the microscopic surface pores, which helps regulate fertilizer
feedings. It can even be supercharged with nutrients before it is added
to the growing medium.

—excellent conditioner for soils that need increased aeration and
drainage, as when growing cacti, bromeliads, succulents, or when
rooting cuttings.

—loosens the density of heavy clay garden soils, letting in the air and water plants need.

—increases water retention in light and sandy soils.

—makes tillage easier.

—reduces crusting, cracking, flooding and shrink-swelling.

—holds moisture in the soil, reducing watering requirements, yet pumice will not compact or become soggy.

—pumice is inorganic, so it will not decompose or compact over
time, meaning it functions continuously and can be recycled and reused.

—pumice is pH neutral.

—pumice does not attract or host fungi, nematodes, or insects"
madabouteu
8 years ago
Unless you can find Dry-stall, a horse care product, you can't find pumice here. It is a volcanic material, and thus it's not found east of the Rockies. Perlite, for some reason, though made from volcanic rock also, IS available and is available. But for my raised beds I blend the cheap "filler" soil (about $2 a bag) with peat and with manure and it makes a perfectly acceptable soil. Add perlite if you wish - I did not find it necessary. I ignored the underlying clay. If the plants want to penetrate the clay, they will. Surprisingly, quite a few will. Rose bushes and the like will do so quite often, annuals usually do not, in my experience. My 2 cents worth. BTW, decomposed granite is not available but crushed granite is available in feed stores, about $6 for 50 lbs. I buy it for use in my succulent soil mixtures.
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From a quick search I learned that at least one company uses DG as a soil amendment to improve drainage and add trace minerals. I don't know how it will affect soil chemistry or PH. The DG would be very useful for a number of outdoor projects including setting rocks and as a soft bedding for the liner if your pond is going to be lined. It's also good for laying stepping stones, paths, levelling various items like the sides of raised beds, underneath posts, underneath a rustic shed, etc. Worst case scenario, you could give it away or trade it for something. If it was expensive and you don't use it maybe you could trade it. Here is a link that might be useful: DG in soil amendment
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Does the Decomposed granite have clay in it?? This differs around the country. I used a washed decomposed granite compost mixture because I fave found that the unwashed clayey stuff does not drain as much as I like. They have 3 grades of DG. I add a pea gravel or crushed granite to mix into the ground for chunky ness. I also add lava sand and basalt sand for fertilizing reasons. I just leaned that the washed granite has other exotic fertile sands mixed into it. I make soil like a cook who stares at the inside of a refrigerator looking for inspiration. I also recommend the addition of blood meal for the roots . Sometimes I add expanded shale as a pumice substitute. No nitrogen I pile all this on top of broken up construction trash to get a good mound going. The guy below adds pine bark to his mixture He has a illustration in the instructions below. I think he used to be in top of Texas gumbo but has moved west. I am not sure what his ground is now. $14 per 40lb would be a steel in Texas. You can't find it in Austin. I pay that for Lava sand and more than that for basalt sand. I buy my DG and soil products from people who sell bulk ground products. where one can load it yourself or get it by the ton or 1/2 or more cubic yard. google bulk soil products for your area or bulk landscaping supplies. I have a place that lets me load up 10 gallon pots full of stuff in my little car . Yes I am a dirty car person. Here is a link that might be useful: Yuccado instructions for dry garden
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We've had people trigger the radiation detectors coming into the nuclear plant due to eating too many bananas. One person in the USA I believe had radiation poisoning from eating too many Brazil nuts. I think the max you should eat are 1 or 2 per day. It does have to do with where they are grown and natural soil radiation. It's everywhere around us and some places just have higher levels than others. Not necessarily dangerous - that's how it is. Shielding is not necessary from such low radiation levels. You will get much more radiation directly from the sun, flights, medical x-rays, rain, snow, etc. I also assume nobody sleeps in their plants, soil mixes, smoke detectors, antiques, propane lanterns, or counter tops all day long every day of their lives. For shielding against significant radiation levels we primarily use heavy concrete, water, lead, and distance.
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Tiffany, purpleinopp Z8b Opp, AL
8 years ago
You would probably gain something of value from this short tutorial on soil microbiology.

http://permaculturenews.org/2013/09/20/soil-not-dirt-dr-elaine-ingham-talks-soil-microbiology/

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