Polymer moisture crystals and the TerraCottem soil conditioner (Dave’s Garden / Willem)

Read at : Dave’s Garden Weekly Newsletter


Polymer Moisture Crystals: Magic for Your Garden and Your Containers

By Jill M. Nicolaus (critterologist)
May 8, 2008

Friends see the lush green plantings at our house and exclaim, “Oh, you have such a green thumb! What’s your secret?” I say, “I water them,” and they look at me in disbelief. But watering – not watering enough, or watering so much that plant roots get soggy – may be the biggest issue for those who think their thumbs are black. Fortunately, it’s often an easy problem to solve. Polymer moisture crystals are one of the best watering aids I’ve found.

Polymer moisture crystals are like magical little garden helpers. They mop up little puddles of water around roots so plants don’t drown. They release the water back to the roots as the surrounding soil dries out, keeping plants from wilting between waterings or rainfalls. If you price them by weight or volume, they seem expensive, but a little bit goes a very long way. They take about 3 years to break down, so they’ll last a while in your garden, too.

Polymer moisture crystals look like coarse salt crystals. They absorb up to 300 times their own weight in water, until they look like little cubes of jello (see photo above). They then release the water slowly back to the soil, keeping it evenly moist between waterings. Good drainage is still important, but by absorbing excess water the crystals help guard against the “wet feet” that make many plants unhappy.

Polymer moisture crystals are a boon to container gardeners. Continue reading Polymer moisture crystals and the TerraCottem soil conditioner (Dave’s Garden / Willem)

Tree seedlings in a plastic bottle (Betula alba)

Since some months, I am experimenting growth of tree seedlings in transparent plastic (PET) bottles.  It’s a real success for a number of reasons:

(1) The potting mix, to which I have added a very small amount of water stocking soil conditioner TerraCottem (5 g per liter of soil), is kept continuously moistened (less evaporation, less heating effect than in the classical black plastic grow bags, used in nurseries)

(2) Individual watering of the bottles has a beneficial effect on plant growth.

(3) I can keep my seedlings in daily sight by having the bottles on the terrace.

(4) When the young trees are tall enough for plantation on site, I will dig a plant hole, cut the bottle vertically in two halves, tear the two halves apart and leave them on the bottom of the plant hole when filling the pit with local soil (to which I will add again some TerraCottem).

(5) This way I will take care of the environment by reusing the plastic bottles and finally burying them.

Here are a couple of photos of a young birch tree (Betula alba) growing in a plastic bottle :

Young birch tree in bottle   Birch tree and succulent in bottle

Young birch tree (Betula alba) and a succulent plant growing together in a plastic bottle. (Click on the photos to enlarge them).

Raised beds combined with containers for inside gardening (Willem)

Today, I received an interesting comment from Anne WALKER on my former posting :

Different aspects of rooftop gardening (Google Alert / Salt Lake Tribune) July 13, 2007

If a garden can be grown on a roof top, how about on the parking lot of an old abandoned strip mall. It is late in the season to start a garden, but we just received funding. We also have donated space in a building located in a strip mall. There is a fenced in area that I’d like to create a few raised beds and perhaps apply lasagne gardening in the beds. What do we do about drainage? How do we keep the soil and water from running out under the beds. Do we line with plastic? Help!!! This is a late summer youth project, funded in part from Community Block Grant and State arts funds.”

Here is my reply to her :

Dear Anne,

Thanks for contacting me and congratulations for your nice ideas.

Raised bed gardening offers a lot of opportunities to embellish our environment or to grow plants in any “difficult” place.

Let us first consider the outside parking lot (or is it inside ?). I see no problem to install raised beds there. Would a bit of water running out be a problem ? Then, I recommend to make the beds a bit higher (1-2 feet), to line the bottom up with a strong plastic sheet forming a shallow reservoir, to fill the bottom part of that reservoir (2-4 inches) with granules of expanded clay (also used in hydroponics) and to cover these granules with a good potting mix to which I would add some water stocking polymers or, even better, a soil conditioner like TerraCottem (see <http://www.terracottem.com&gt;).

About the raised beds inside the building : see above, as I cannot foresee any problems with water.

Let me now make another suggestion !

Why don’t you construct a raised bed and fill it up with containers (each of them perforated at its bottom for drainage). I am thinking at the classical plastic flower pots, but also at PET bottles or even big plastic party cups (use your imagination).

The raised bed should be constructed like the one described above : with plastic lining at the bottom, but without clay granules. The containers (pots, bottles or cups) can be put directly on the plastic sheet (in the so-called reservoir) and filled with a good potting mix (mixed with water stocking soil conditioner), then seeded or planted. Now all the containers are covered (mulched) with a thin layer of potting mix, so that one cannot see the containers anymore (only a nice layer of soil under which the containers are hidden). When watering such a raised bed, most of the water will be running into the containers and stocked in the polymers. A surplus of water, running through the containers or through the open spaces between the containers, will run into the plastic sheet reservoir and only a minimum will be kept for a short time on that plastic sheet (from where it will be gradually absorbed by the potting mix in the perforated containers).

I can imagine that after a while one would have to add a thin supplementary mulching layer of potting soil, for the soil will slide partly down into the open spaces between the individual containers.

I never did this before, but I can imagine that this would be quite successful. Worth trying, I think !

Please keep me informed and possibly send me some photos of your realization. I will gladly publish them on my blog.


Best way to keep container soils moist? (Willem)

Already published at my desertification blog on March 9, 2007

Best way to keep container soils moist?

March 9, 2007

Posted by willem van cotthem in fertilizer – nutrients, success stories – best practices, soil, water, technologies. trackback , edit post

Working for more than 20 years already with water absorbing polymers (also called “crystals” in gardening circles !) and having developed the soil conditioning method TerraCottem (see http://www.terracottem.com), I was very much intrigued when I encountered on the internet a discussion forum on “the best way to keep container soils moist“.

Let me take you through some nice and sometimes amusing contributions about several topics related to moist soils (!): Continue reading Best way to keep container soils moist? (Willem)