Napa 8822

Silenus · Post by **Silenus** » Tue May 19, 2009 7:31 pm

Well I figured I would raise this point, NAPA #8822, cat liter, etc are all designed to absorb moisture. Perlite is designed to spread it out over the surface and drain, wouldn't perlite be what you want in the mix since these other materials are holding in water.

lancer99 · Post by **lancer99** » Thu May 21, 2009 1:12 am

CoronaCactus wrote:I've noticed a thin crust layer (1/4" or less) on some seedling pots that i let dry out too much.
Another thought would be too much sand or fine soil (clay?) to clog up the works...?

Did you use any top dressing?

No top dressing, just a mix of Scott's brand topsoil with the Napa. I had just washed the Napa, so it was completely saturated, and that resulted in a crusty surface. I broke the crusts up, and since then have just been giving sprayings/light waterings on the plants that I potted up with that mix.

I gave most of the new pottings a thorough soaking today, and will be away in MTL for most of the next week, so it will be interesting to see if the crust re-forms.

-R

iann · Post by **iann** » Thu May 21, 2009 1:02 pm

Well I figured I would raise this point, NAPA #8822, cat liter, etc are all designed to absorb moisture. Perlite is designed to spread it out over the surface and drain, wouldn't perlite be what you want in the mix since these other materials are holding in water.

You're right about one difference between perlite and clay granules. The perlite definitely holds less water, a lot less. Perlite has a closed pore structure which means water can't get to the interior. This makes it very light even when its wet. Clay granules have an open pore structure which means water can slowly soak into the interior, obviously a lot more than can sit on the outside of a piece of perlite or grit.

But water isn't poison, saturated airless soils are poison. Grit maintains air within soils because it is large enough to keep air pockets between the grit pieces even when they are wet. Its not very good at this because that's not very much air unless you use very large grit and because other soil components can get in between the grit and exclude the air. If you don't have enough grit, enough for the individual pieces to touch eachother and maintain air pockets, then it does nothing except make the soil heavier and even exclude air.

Perlite can maintain air in the soil because of the pores on its surface which avoid being clogged by other soil components and don't easily fill with water. I find soils with perlite to be extremely dry, but presumably this works better when other components of the soil mix hold water better.

Clay granules maintain air in much the same way as perlite but they maintain both more air and more water, as water is drawn into the interior of the granules. It is very difficult to completely saturate a soil with clay granules in it unless you stand it in water or leave it in the rain for quite some time. Otherwise the granules just draw in water and leave you with moist soil rather than soggy soil. Then as the soil dries out, the granules slowly give back the water.

Silenus · Post by **Silenus** » Thu May 21, 2009 1:09 pm

Excellent explanation, so it would not be a real danger to succulent as it is not providing a constantly damp environment.

iann · Post by **iann** » Thu May 21, 2009 1:43 pm

Not constantly damp unless you want it to be, but they do provide moist conditions for longer, rather than a soggy soil that is bone dry a few hours later. Nothing wrong with that dense soggy kind of soil but it is best suited to hot climates and advanced growers because if it lasts for long then you'll quickly lose plants.

What the clay granules do is make it easier to maintain a moist soil for more than a few hours that isn't completely saturated. Soils in pots tend to saturate because of the boundary at the bottom of the pot, that's why your nice well-drained garden soil is suddenly like a bog garden when you put it in a pot. Saturated soils are for Venus Fly Traps, not Ariocarpus

Silenus · Post by **Silenus** » Thu May 21, 2009 2:46 pm

Good point. Keeping a once a week or so watering schedule even more scare perhaps would work out fine with the NAPA then. I am just working with it and perlite, trying to figure out the better of the two for my current environment.

lancer99 · Post by **lancer99** » Thu Jun 04, 2009 3:34 am

One thing I've noticed about my new mix, 2-3 parts Napa to 1 part potting soil, is that water goes straight down from the top of the pot to the bottom.

In other words, you can thoroughly drench a plant in the middle of a pot, but the mix in the sides of the pot will stay bone dry.

Not sure whether that is a good or bad thing....

-R

Silenus · Post by **Silenus** » Thu Jun 04, 2009 1:19 pm

Sounds good, just water around the pot not in one centralized area though, that should help give the rest of it a healthy drink.

iann · Post by **iann** » Thu Jun 04, 2009 1:24 pm

water goes straight down from the top of the pot to the bottom

The mix might be just a little bit too coarse, too many gaps not trapping the water at all.

Hiro · Post by **Hiro** » Thu Jun 04, 2009 3:29 pm

I have started using a mix of
1 part Schultz aquatic Soil
1 part nappa in canada it's #623 i think i'll have to check when i get home
1 part black earth/chor mix
i find the nappa diatomite dries out nice and quick i just started using this so we will see how it last in the long run but nothing has died so far

Silenus · Post by **Silenus** » Thu Jun 04, 2009 6:02 pm

I would drop the shultz aquatic soil and replace it with something like filler sand. By black earth you mean gardening soil, correct? If so it is a good mixture providing the amenities I just made, just be sure there aren't a lot of big sticks or anything in your soil, bugs love that. I seem to never be able to find a bag of soil that doesn't contain all kinds of large rotting sticks or such.

swords · Post by **swords** » Fri Jun 05, 2009 7:06 am

Silenus, if you get a piece of poultry screen from the hardware store with small 1/8" gaps you can grind your peat (or coir) on it and get only fines in the soil mix. Keeping all the clods and sticks up on the screen. Building a 18" x 18" frame from 1" x 4"s and stapling the screen to it makes it even easier yet. I toss all the sticks but use the clods for CPs, they seem to like those coarse clumps blended with Napa.

If you haven't tried it, the 2.2 Cu Ft bales of Greensmix Canadian Sphagnum Peat Moss avaialble at most all garden centers is much better material "With fewer twigs and clumps than the other leading brand!" It's also cheaper than those pre-bagged soils.

Moonbeam · Post by **Moonbeam** » Wed Jun 17, 2009 1:35 am

I have another question about this...I'm tired of the perlite floatin' and flyin' around, and was going to switch to the NAPA 8822, but now I'm worried about the moisture retention part of it. We're gettin' pretty warm down here, and our air is thick! This week it has been averaging between 93º and 98º, and with the humidity/dew point at at least 70%. But, it hasn't rained in over a month. As the summer goes on it will get warmer and muggier. In the mornings, it's so dewey it appears as though it has rained. Really, I'm not exaggerating. There are puddles around from the overnight dew.

So, wouldn't this be too much moisture already with using the NAPA 8822? Does it really retain moisture to a point of concern?

I can't find pumice...

Silenus · Post by **Silenus** » Wed Jun 17, 2009 3:10 am

It doesn't retain enough moisture to make it worth worrying, if it is hot as I assume it is where you live it will evaporate fast.
I live in Florida and I have had no issue with it so far, we are just as muggy with humidity in the 70%+ and temps for 93F.

iann · Post by **iann** » Wed Jun 17, 2009 11:26 am

Bacliff, TX today with a dewpoint of 75F. Note that at 95F this corresponds to a relative humidity of 50%. Of course at 75F it corresponds to 100% relative humidity.

Here in England the dewpoint never reaches 75F. I don't have the records but I'd say not ever. We have a different sort of humidity, with low temperatures so that the relative humidity is high and evaporation is extremely low (or negative with net condensation!). Today the dewpoint is 54F and the temperature 57F, relative humidity 90%. That is why the UK is considered to be a green and moist place even though many places have less than 30" of rain each year. On the other hand, inside my greenhouse the temperature can top 100F but the dewpoint is still the same so the relative humidity is desert low.

I don't have a problem with the cat litter retaining too much water. Certainly it soaks up more than perlite but then I find perlite too dry. It all depends on how much you use since the soil components holds far more than either. If I use sufficient cat litter to create the soil texture and drainage that I want then it dries out very rapidly. To create the same texture and hold even less water, replace some of the NAPA with grit. Your top dressing and pots will have a far greater effect than changing perlite to NAPA. Also a tiny amount of extra sun or wind would have a bigger effect.