WHATS THE DEAL WITH SHRIVELY ROOTS? - Orchid Board

xxkarliexx · #1 06-20-2012, 04:21 PM

ive noticed on lots of orchids ive seen that look SUPER healthy and have a lot of good healthy air roots but how come some of them have roots that look dry and shrively? not black or mushy just...dry? do orchids ever have roots that die off naturally or something?

Bud · #2 06-20-2012, 04:28 PM

there are environments that dry out aerial roots....that is why it needs to be sprayed in the morning and give it a chance to dry all day....some water it only a week being scared of overwatering and root rot...
on environmments where there is ample humidity in the atmosphere, the aerial roots are fat, robust with silvery color that turn green when you wet it.

xxkarliexx · #3 06-20-2012, 04:38 PM

so on my new mini phal that has some i should water it how i normally would (when the medium is nearly dry) and spray the shrively ones? i guess my real question is are these roots totally done or will they become healthy and fat again? also how often should i spray them? is every day too much?

james mickelso · #4 06-20-2012, 10:29 PM

Arial roots are just normal roots that aren't down in the media. They are one and the same. In nature the orchids grow on tree branches and get moisture when it rains. What you see (arial roots) on yours is what they would look like in their natural environment not what they look like under the media we put them into. Their roots get nice and plumped up when they are wet. During the dry season these roots can shrivel and just lay there looking dead. But when it starts raining again they either plump back up or grow new root tips and start elongating into fat water filled roots. What you see as shriveled root is actually called velamin which covers the real root. It is a spongy material that absorbs moisture very quickly giving the root inside more time to absorb the moisture from it. This is what usually rots when kept too wet. So what I try to do with these "air" roots is to slowly bend them around the surface of the pot until next time I pot they fit into a small pot. If allowed to grow out like most of them do, they won't fit into the pot next time you repot. Just tie a string onto the middle and end of the root and slowly pull it into the edge of the pot. Don't break it. Yes it will heal but it sets it back quite a bit. Just pull it gently with the string over a week or two. Or when you see a new root devloping above the surface of the media just redirect it with something substantial like a stake or rock. You can mist or spray these "air roots" as often as you like because they dry quickly and the bacterial and fungus that causes root rot usually doesn't grow in open air.

King_of_orchid_growing:) · #5 06-21-2012, 12:15 AM

Actually...

With Phals, yes, they do grow on trees.

Yes, the air is humid where they grow and that is where part of the moisture they get is coming from.

Yes, they do generally grow in seasonally wet subtropical to tropical Asian rainforests, and the rains do provide a good portion of their moisture.

But...

They do not just get their moisture from the humidity from the air and the rain...

Some live in seasonal swamp forests. The trees are partially submerged in water. The water is wicking up the trees providing moisture to the orchid's roots.

Some live in seasonally wet forests on limestone rocks. Limestone can stay moist for a considerable amount of time. So when it rains, the limestone retains moisture, thus providing the necessary moisture for the Phal's roots to use. Limestone can also wick up water from the ground. If the ground is very wet, the limestone will take up that water and provide moisture to the orchid. With high humidity, the limestone retains moisture for much longer. It also helps that the humus on top of the roots keeps moisture in as well.

Where's the evidence?

Here it is, just so you know I'm not spewing out nonsensical stuff:

Visiting Phalaenopsis cornucervi (orchid) habitat in the swamp of Borneo-part 1 - YouTube

Visiting Phalaenopsis cornucervi (orchid) habitat in the swamp of Borneo-part 2 - YouTube

Visiting Phalaenopsis cornucervi (orchid) habitat in the swamp of Borneo-part 3 - YouTube

Visiting Phalaenopsis cornucervi (orchid) habitat in the swamp of Borneo-part 4 - YouTube

Visiting Phalaenopsis cornucervi (orchid) habitat in the swamp of Borneo-part 5 - YouTube

Phalaenopsis in natural habitat ( in situ) - YouTube

Phalaenopsis maculata in situ

The point being is that the roots have to have adequate moisture in order to stay plump and alive. Too much moisture rots them out. Too little dries them out. Figuring out the right amount for your orchid is the art. Knowing how the orchid obtains moisture is the science.

King_of_orchid_growing:) · #6 06-21-2012, 12:42 AM

Forgot...

Yes, orchids do have roots that die of old age, but it takes a very long time for that to happen.

It's difficult to pinpoint a timeframe, so if that's the next question, I can't answer that.

King_of_orchid_growing:) · #7 06-21-2012, 01:00 AM

Oh yeah...

Yes, aerial roots are essentially the same as the roots in the pot. Aerial roots are more adapted to growing in a drier environment. Roots in a pot are more adapted to growing in a more moist environment.

It is also a science to understand the biology and physiology of an epiphytical orchid root. I think they're very interesting subjects.

james mickelso · #8 06-21-2012, 01:05 AM

Phals can go quite awhile with no moisture at all. When the phal has root damage the worse thing you can do is to keep the roots wet. That is what caused the problem in the first place. Moist is fine but not wet. The wet roots just keep the bacteria and fungus growing so letting them dry for awhile stops or radically curtails their growth. Misting the phals leaves especially the undersides provides enough moisture to keep the phal alive until the new roots can grow. The existing leaves provide starches (sugars) and moisture to the growth to keep it going until the roots can again provide water and food to the growing plant. We are talking about a month or two. Not a year. I have two orchids that continue to grow with little in the way of water or food. One is going on 4 months with no roots but a new leaf. One is going on 3 months and is finally putting out two roots. When I first started rescuing phals (orchids in general), the only plants that failed to grow were those I kept too moist. Those that I withheld water from are still alive. You don't want to desicate them. That is why you mist them, mist the undersides of the leaves especially so that the leaves can absorb moisture through their stomata. But time and time again folks get phals that have already begun to deteriorate yet it isn't noticable until you take it out of the pot and look at the rots. Plant looks fine but the roots are turning to moosh. So they cut off the roots and replant just to exacerbate the problem. Phals and most other orchids can withsrtand being dry for a short length of time. Here are two that are doing well and are watered once every two or three weeks. One has flowered with no ill affects and the other is growing a new leaf.

King_of_orchid_growing:) · #9 06-21-2012, 01:12 AM

James talks about misting the underside of the leaves...

What he didn't explain in detail is why...

Here's why-

On the underside of leaves, there are what are called stomata. Most vascular plants with leaves have what are called stomata underneath their leaves. Stomata are a plant's pores. They let moisture in, and they let moisture out. They also help the plant breathe. These are also important in the regulation of other plant processes such as having some part in photosynthesis (to keep things simple). They can open and close, (this is done by a special set of cells).

Because a plant's stomata can let moisture in, that's where the idea of foliar feeds and wetting the leaf's undersides come from. Science has already provided strong evidence that supports that vascular plants with leaves (orchids included) can obtain nutrients from the moisture that is being absorbed by their stomata.

There might be some scholarly articles on stomata and nutrient uptake from the underside of leaves on the internet. Try doing a search on Google Scholar and see what you can pull up. I mention this to back up what I say. I just can't cite a specific source right now because I don't have time to search it out and provide a link. Plus I forgot what that specific source was. I do know a scientifically peer reviewed article has been written about the subject matter though.

Here's a link to a photo of what stomata look like. It belongs to the petal of a Phal. If you're wondering - a petal is a modified leaf, so I'm not way out to left field on this:

Orchid petal, SEM

james mickelso · #10 06-21-2012, 01:28 AM

The more I learn about them and grow them the more I lov to find new ones that I don't have. But I only get the rescues. I'm cheap and I don't have any more room darn it. I would like to get some of the phals that are native to the Himalayas. They grow up to 8000 feet and are cold growing. It mut have taken a long time to get that far and evolve to be so different from their cousins in Australia. Too bad that so many like Robinsonii are extinct. It would be nice to find some of them and collect seed. But I'm too old for anymore adventures. No more rings for me.