For those of us who hate watering

[calvin_orchidL]

Originally Posted by Becca

I'm not any help with input on the potting medium, but I would like to know where I can find out more info on root behavior and what my roots are trying to tell me. I have been told that if roots, say with a phal, grow up and away from the potting medium, that it is a sign that they don't like the potting medium. I have orchids with roots that circle the bottom of the pot, but also have roots every where else....I thought it was a sign of the roots being happy and part of the process of becoming root bound. So can someone point me in the right direction where I can find out more info on this subject? Thanks for any help...and I am really enjoying this thread, I find it very interesting!

Great questions, Becca. The root issue can be puzzling, and can be seen as quite evident on mounts. I have mounted orchids that occasionally grow roots up and away from the mount, and then go through phases where the roots cling tightly to the mount, grabbing hold. I suspect it may be due to ambient humidity - ie if the mount offers more moisture and the plant is thirsty, it will cling to the mount. If there is abundant moisture in the air, the roots might deviate from the mount. I also find that roots that grow away from the mount end up actually attaching to neighbors quite tightly...suggesting that aerial roots could also be growing out for support purposes in addition to moisture/humidity reasons. I have several species which get sprayed quite liberally on one side of the mount, while the other side is quite dry. Oddly, the majority of root growth is occuring on the dry side, with roots clinging tightly to the mount. I would suspect that the moist side of the mount would attract roots...it just goes to show that root behavior is really complex...if anyone can chime in about this, that would be really great.

Along a similar vein (but somewhat off topic) - do you people increase watering and fertilizer with new root growth, or with new leaf growth? This is obviously genera specific (since some species will have very obvious and consistent root/leaf growth habits...ie some cattleyas and dendrobiums). I have several monopodial species that seem to be growing roots left right and center, and yet leaf growth has stalled. What does this mean? What is the plant trying to say?

[Ray]

The "non-uniform" moisture in LECA is determined by the rest of your growing conditions, particularly humidity, temperature and air movement.

If evaporation is slow, and the LECA you're using wicks well, it will be very uniform bottom to top. If the evaporation rate exceeds the wicking capability, there will be a gradient.

However, when you consider that a well grown plant will put its roots right down into the reservoir, it doesn't matter anyway.

Concerning the "language of roots", I tend to think about it in terms of their function.

Of course they are for water and nutrient uptake and waste elimination, but they are also the plants' anchor to their growing substrate. Calvin's plants growing roots on the back side of mounts is for mechanical advantage, and has nothing to do with the relative moisture levels. I believe that is true with Becca's phals, too.

A phalaenopsis has a lot of vegetative mass on top of a fairly small "base". As the plant gets taller, those roots are reaching out to "grab hold" of something to stabilize the structure - sort-of like guy wires on an antenna tower. I find that if I put phals into very large pots, they send those aerial roots down into the medium spontaneously.

I am not ruling out their aversion to crappy medium, but how many times have we seen new growth on nearly rotted roots in decomposed and compressed bark or sphagnum?

[Undergrounder]

Originally Posted by Ray

Concerning the "language of roots", I tend to think about it in terms of their function.

Of course they are for water and nutrient uptake and waste elimination, but they are also the plants' anchor to their growing substrate. Calvin's plants growing roots on the back side of mounts is for mechanical advantage, and has nothing to do with the relative moisture levels. I believe that is true with Becca's phals, too.

A phalaenopsis has a lot of vegetative mass on top of a fairly small "base". As the plant gets taller, those roots are reaching out to "grab hold" of something to stabilize the structure - sort-of like guy wires on an antenna tower. I find that if I put phals into very large pots, they send those aerial roots down into the medium spontaneously.

I am not ruling out their aversion to crappy medium, but how many times have we seen new growth on nearly rotted roots in decomposed and compressed bark or sphagnum?

I don't think its an aversion to crappy medium, but an aversion to dry medium. And similarly, if crappy medium is rotting and killing the roots, then its the same thing. Its an aversion to dehydration.

My theory is this. If a Phal. is not getting sufficient water, then the first thing it should do is to grow new roots. It makes evolutionary sense that it is dehydration that stimulates root growth, since roots are the things that fix dehydration.

And this new root growth is likely to be from dormant eyes in the crown of the plant, which tend to turn into 'aerial roots' when they form up above the existing medium.

So plants that are kept too dry, either from dry medium or from crappy medium that has rotted the roots, are going to have a lot of 'aerial roots'.

Compare it to a plant that is getting plenty of water. It makes evolutionary sense for new root growth to come from the old root system. Either by the continued elongation of old roots, or by the root system forking and growing larger that way. It's been established that the root system is doing a fine job of providing water to the plant, so its going to want to put more roots in that area.

But when that root system can no longer support the growth and function of the plant, THEN new roots are stimulated from the dormant eyes further up the crown, which would possibly grow into new areas that are able to provide more water.

And that's the reason why i think the properly hydrated plants got no aerial roots in this experiment:

Frequency of Watering and the Growth of Phalaenopsis

[Louis_C]

I'm using 2 part sphagnum moss : 1 part of pumice. New growth so far after blooming. It a rescue plant from Lowe's being completely unroot when I found it. It doesn't get too soggy and never dry too fast. Compare to pure sorghum it much easier to absorb water.

[stefpix]

what is pure sorghum?
is the pumice the gravel for aquariums you can get at the pet store?