what are you growing.. where.. and why do your plants need more moisture..

outside.. potted... in a green house.. house plants.. etc...

the more info you give us.. the better the answers will be..

if all your pots have the same stuff. then you can adjust moisture thru your watering regimen ... so why mess with the tried and true formula???

ken

The whole 5-1-1 idea is irrational for so many plants…

Failure is guaranteed.

@Iochroma, can you elaborate on why you think that?

iochroma, I actually find the concept behind the 5-1-1 mix to be brilliant, I just wasn't able to water frequently enough. In a future season of life when my young family is more grown up, I will experiment with the 5-1-1 again to try and make it work for me. I'm thinking a 4-1-1-1 mix of bark-peat-perlite-turface. Or maybe I'll just try the gritty mix.

Customers at the store where I work frequently ask me what soil they should use with their houseplants. I never know how to answer that because truthfully, I don't recommend any of them! I was thinking maybe the 511 would be a good general mix to recommend, but then I got to thinking that might be challenging because it dries out relatively quickly. Unless...the person uses glazed ceramic pots...hmmm...I need to think on this some more...

The idea that the 5:1:1 mix dries out too quickly has long been promulgated by folks who have read that somewhere but haven't tried it, by those who tried to follow a recipe using substitute ingredients or bark that is much too large to be used as the largest fraction of a medium, and those who have tried something that resembles the 5:1:1 or gritty mix but don't understand the concept that drives their efficacy, or the fact that the mixes are adaptable insofar as water retention is concerned by changing the ratio of ingredients or introducing additional ingredients. Both the gritty mix and the 5:1:1 mix are adjustable over a wide range of water retention with very little change in air porosity at container capacity. Container capacity is a measure of how much water the grow medium in a pot or container holds at the moment it has stopped draining, after having been watered to the point of complete saturation. When plants are at 'container capacity', the medium often supports a layer of grow medium that remains 100% saturated (a perched water table [PWT]) which occupies a layer of grow medium at the bottom of the pot, defying the force of gravity and refusing to drain. The ht of the PWT and how long it affects root function is usually key/critical in determining what opportunity a plant will have to realize as much of its genetic potential as possible (within the limiting effects of other cultural influences). The factor that most affects the ht of a PWT is the size of the particles from which the medium is made.

The truth: All else equal, a medium that holds almost all of its water on the surface of the particles that make up the medium, in the internal pores of of soil particles, and at the interface where soil particles contact other particles offers a much greater opportunity for a plant to realize as much of its genetic potential as possible. An ideal medium (from the plant's perspective) would hold no, or precious little water in the space between soil particles. For this to occur, the medium must consist of a very large fraction (>75%) of coarse material that won't fit through a 1/8" screen. If a medium is made from particles that won't fit through a 1/8" screen it will hold little or no water between soil particles, meaning the entire soil column will still be highly aerated even at container capacity.

The recipes I have provided are useful as starting points and can be very helpful in moving growers along the path to a green thumb, but an understanding of the concept behind these media is far more valuable than the recipes because the concept frees growers to make informed changes based on the physical properties of the ingredients they have available and/or are working with.

I've often heard growers grouse that one or the other mix won't hold enough water for plants in say TX or FL summers. There are 3 ways to fix that issue. 1) Use a mix that favors the plant (holds little excess water) and water more frequently 2) Add an additional volume of internally porous ingredients to increase water retention w/o changing air porosity at container capacity. 3) Use a medium that holds enough water to allow the grower to water at intervals that better favor how the grower's priorities are ordered. The 3 choices are in the order that favors the plant. IOW, the plant would much rather be in a medium that needs watering twice per day during extreme weather than in a medium that allows 2-3 day intervals between waterings; this, because the additional water which allows the longer intervals will be held between soil particles at the expense of air porosity, and that is a limiting factor.

To be at its best, a plant of any genus/species WANTS the same conditions in TX/FL as it does in MI/NY - the same amount of light, same soil temps, the same humidity, the same grow medium including moisture levels, the same fertility levels and nutrient ratios ..... . Unfortunately, the weather forces many growers in the deep south to make choices that make their watering obligations less demanding. The choice to use a medium that needs water only every 3 days as oppose to every day or even twice a day comes at a price because what the plant wants and the growers convenience are pretty much mutually exclusive when it comes to maintaining a balance of water:air in the rootzone.

So to repeat, if someone understood the concept behind the soils, it wouldn't allow them to (in good faith) make the claim that the 5:1:1 or the gritty mix and their variations don't hold enough water to raise extremely healthy plants for geographical reasons because they are based on a concept that makes them adjustable for water retention; and, if the grower was willing to water at appropriate intervals, they would find that healthy plants can be grown virtually anywhere temperatures allow - in a bucket of broken glass or for that matter, with no grow medium whatsoever to act as a water reservoir.

Al