foliar feed
 

Does anybody use Orchid Focus feed I looked at there online instructions and it states that it can be used as a foliar feed.
I assume if you foliar feed you do not have to root feed is this the case or should one vary by using somae as foliar and say every forth as root feed ?????

Foliar feeding does not work well for orchids. Someone else on the forum can probably give you the technical reasons but I know from experience and from reading that it doesn't work well.

I have used Orchid Focus and it gave me very good results (in the medium, not foliar). It seem to have an especially good effect on my phalaenopsis. There are two problems with Orchid Focus. It's expensive for the small amount of fertilizer you get. Secondly it only has the major nutrients. It doesn't have a full range of micro-nutrients. So you would need to alternate it with complete fertilizer that has micro-nutrients. I think the reason it works well is that it gets 100% of it's nitrogen from nitrates. That's the best source of nitrogen for orchids.

In order to understand the principles behind foliar feeding, you have to understand some slightly advanced physiology of a plant.

Plants have pores on their surfaces called stomata. The area of a plant's leaves where the stomata are present is on the underside of a leaf, not the top. Being that the stomata on the leaves are located on the bottom of each leaf, it must be remembered that most of the times, as far as I understand, not a lot of forms and significant sources of nutrients can stay adhered to the surface of the underside of a plant's leaves for very long, particularly if the plant is an epiphytical orchid that grows high up off the ground in trees.

Stomata can open and close and is used for not only gas exchange, but for controlling the plant's ability for moisture retention as well. It also has the capability of absorbing moisture off the surface of the underside of the leaf. In nature, this moisture is most likely to be in the form of dew drops.

In an orchid, it is said that the number of stomata present on the underside of the leaf is less in number compared to some other types of flowering plants.

Given what you know now, you can start to see how foliar feeding is still possible, but the effectiveness is limited by where the stomata are located, and the number of stomata each leaf has.

The surface area of an orchid's root mass on the other hand, has the ability to at times, far exceed the surface area of the orchid's leaves. The increased surface area of the roots make the roots a far more efficient and effective method for the plant to obtain water and nutrients from its environment. The roots are also better designed for water and nutrient uptake than the leaves are. In many epiphytical orchids, the roots are far more likely to trap and catch many more different sources and forms of nutrients than the orchid's underside of the leaves can.

The above explanation is most likely why "tucker85" has experienced what he has with foliar feed vs "root feeding".

Thank you for your help explained very well

I agree with Philip. I find foliar feeding effective only when the plant has insufficient roots. I've been able to save rootless orchids by misting the undersides of the leaves on a daily basis and then adding dilute fertiliser once I see some indication of recovery (like the leaves stop dropping or the pbulbs start to plump up slightly). Same principle as sphag and bag really. You're just allowing moisture to be absorbed through the stomata - either by raising the humidity by putting it in a bag with wet moss or by wetting the undersides of the remaining leaves.

If the plant has a good root system then I wouldn't really bother with foliar feeding, but it won't hurt.

Liquid nutrients are not absorbed through the stomata, but may be transferred into the plant through cells referred-to as "plasmodesmata" that are closely associated with them.

When it comes to orchids, almost EVERYTHING is a matter of degree.

Highly polar, ionic species, like the nitrates and ammonia-based nitrogen sources are very poorly absorbed through the plasmodesmata, while low polarity urea is better absorbed. If we shift to the roots, the opposite is true - the less-polar urea is very poorly absorbed while the other nitrogen sources are preferred.

That said, I have to question why you'd want to feed a plant with no roots in the first place. Doing so does nothing to stimulate root growth, so you'd be better off treating it with something containing auxins to stimulate the growth of new root tips, and THEN feeding it normally.

I don't think anyone suggested feeding a rootless plant normally. :)

The main problem with no roots is hydration. If the plant looks like it's staying sufficiently hydrated because you're increasing humidity, misting under the leaves, lowering light levels, etc. then I can't see any reason not to give the plant a little foliar feed (it can't take up much anyway). As long as there is enough water in the plant's cells to maintain their structure and facilitate photosynthesis then the plant can still use the nutrients.

If the plant keeps dropping leaves, has droopy leaves, and/or pbulbs continue to shrivel, then yes, feeding would be useless because there wouldn't be enough water present for all the necessary chemical processes to occur.

That's my understanding anyway.

It's a good point to make Ray, even if it wasn't suggested here. I had a paph that had lost all roots and I kept it alive for 18 months by foliar feeding... but it never grew new roots. I gave up the daily feeding when I bought a replacement and it then started to fade.

I wonder if it wasn't encouraged to grow roots because it was getting what it needed other ways :hmm I didn't think of using seaweed on it and only found a good seaweed after this one had died. I wonder if I could have saved it that way :hmm

I foliar feed 3 times weekly with nutrients. I use an organic wetting agent Surfactants. I mist the tops and underside of the leaves. I clean any build up off weekly. I use different blend of nutrients the 3 times. It does get absorbed, how much I don't know for sure. I also mist 3-4 times a day with Ro water. I do grow indoors and the heats kicking right now, hard to keep humidity above 50%.
Try a test. Like I did. Cover any roots and mist a leave with Epsom salt see if you get and color change (darker green).
I do like to experiment.
My next is misting with club soda.
Also adding methanol to one of my waterings only on a few select orchids of course. Don't know how it will turn out.

---------- Post added at 10:32 PM ---------- Previous post was at 10:30 PM ----------

I didn't see this post was a year old. Forgot it was 2014.

A simple review of foliar feeding in orchids:

http://cochran.agrilife.org/files/20...on.pdf#page=43