S/H medium won't dry between waterings

[Lissbirds]

Hello all,

I've been in the process of switching over all my orchids to S/H (Primeagra brand) over the past couple of years. I've always had pretty good success with it, and I like it because I have a tendency to overwater.

However, I bought a new bag of Primeagra and some new S/H pots over the summer and repotted a couple of my plants. (An oncidium, den/phal, and a few phals.) I've been noticing that the primeagra isn't drying out like it used to. Nothing else has changed in my watering habits. I did repot the oncidium, den, and one phal into 5.5" to 6"-sized pots, and I'm wondering that perhaps the post size is too big. Any thoughts?

One other thing I noticed is that the two holes at the bottom of the new pots seemed a little smaller and closer together than the pots I had bought a few years ago. I'm wondering if this is affecting draining? But I'm not sure that is the culprit as even when the reservoir is empty, the clay rocks are not drying out. I know the Primeagra did change recently as the pellets look a little different now.

I just repotted a phal and all the roots were rotted away. Luckily it's a good root-producer and there's a lot of air roots so I think it will pull through. I was just stunned that there would be so much root rot in an S/H setting. Now I'm worried about my other plants.

Any ideas? Should I poke more holes in the pots, use a smaller or shallower pot, or just switch back to a typical potting medium?

Thanks!

[cassier]

I wish that I could help.
I'll leave it to the experts in S/H.
This is my opinion.
It could be the holes or the change in product.
If after you put extra holes it remains moist,
I would call the maufacturer.

[patticake]

I don't know a lot about s/h...but I thought the idea was that the medium stayed damp?

[Lissbirds]

Well, it stays a little damp between waterings, but not "wet", and I would never notice the surface of the Primeagra "rocks" being so damp. The fact that the surface of the rocks isn't drying out between waterings would make me think that the whole rock is saturated...and I've kept to the weekly watering schedule so I'm guessing I'm overwatering.

Before the Primeagra changed, the rocks would slowly dry out over the course of a week until they were completely dry in about a week's time. They don't seem to be drying out at all anymore. Maybe the new rocks are denser than they were before and holding more water.

[articuno75]

Remember these are kiln fired clay pellets. Still clay and with time can break down with the over absorbtion of water. (ever seen a clay pot that got wet and stayed wet over a period of time? It crumbles and deteriorates faster.) The clay is holding more retention. This is normal. You don't have to change the medium, but do change your watering habits. As for the holes, this sounds more like build up around the area. See if you can "unplug" those holes. Mine narrow down due to the mineral buildup from the water. I have to clear the holes every so often when I notice poor drainage occuring.

[janet_a]

what jenny said. each batch of clay is different, and may use a different binder in firing. as the clay ages it holds more water.

and i too have to unplug my holes periodically. if you're really concerned, crack out the ice pick and punch a few more holes in the sides on the level with the original holes. but as long as you've got air movement over the tops of the pots i wouldn't worry about it.

[LouisW]

I think that you could also make more air holes in the sides which would all allow more air flow that would waft away some of the humidity building up in the pot.

[GrowInHydro]

I've been noticing that the primeagra isn't drying out like it used to.

I'm confused as to why you are "drying" the media between watering. That is not semi-hydroponic culture, it is just hydro media in a plastic pot If you want the pellets to dry after watering I would just pot it up in a regular plastic or terracotta nursery pot.

You don't want the media to dry, you want to keep it hydrated and get into a routine of watering just before the reservoir goes dry. Remember, this a "hydro" culture so you want to keep the water in there.

Remember these are kiln fired clay pellets. Still clay and with time can break down with the over absorbtion of water. (ever seen a clay pot that got wet and stayed wet over a period of time? It crumbles and deteriorates faster.)

The "clay pellets" are actually no longer a clay once taken past quartz conversion (1063*F). The now ceramic, is becoming vitrified and the hotter it is fired, the tighter the "pores" and the less the ceramic is able to absorb water. I think most LECA are fired in the 1800 to 2000 degree range.

Total vitrification yields a water tight ceramic that has no ability (or pore space) to absorb water. To put that in to context, it is like the difference between stoneware and a porcelain. All stone or earthenware ceramics that are utilitarian are glazed to waterproof.

I don't believe you are seeing any of the PrimeAgra deteriorating. The clay pots you see breaking down in your yard are doing so for a few reasons:

The main reason the pots in your yard breakdown is due to freezing. The water retained by the pot expands in the pores of the ceramic and it cracks.

Another reason is that the cheaper pots are mass fired and the temperatures are not consistent though the kiln. Pots in different areas of the kiln reach different temperatures so the vitrification of wares throughout is varied. In other instances kilns are deliberately fired low to save on fuel costs and are only just fired past quartz conversion. This produces a weak ceramic and can easily weather over time because only the surface of the pot had reached temperature enough to vitrify, the the core of the pot walls didn't reach quartz conversion. As water is absorbed into the pot, the un-vitrified clay stays wetter than the ceramic surface that shrinks as it drys and the tension cracks the pot.


Jesse

[Lissbirds]

Well, it can't be that the PrimeAgra is deteriorating because I just ordered it in August and I doubt it breaks down that fast.

Originally Posted by GrowInHydro

I'm confused as to why you are "drying" the media between watering. That is not semi-hydroponic culture, it is just hydro media in a plastic pot If you want the pellets to dry after watering I would just pot it up in a regular plastic or terracotta nursery pot.

You don't want the media to dry, you want to keep it hydrated and get into a routine of watering just before the reservoir goes dry. Remember, this a "hydro" culture so you want to keep the water in there.

Hmm...it's kind of hard to explain what I'm seeing. Obviously you wouldn't want the media to dry up completely but the media will be drier right before watering, right? From what I can gather from reading the info on the PrimeAgra site, the pellet will retain some moisture on the inside of the pellet, hence keeping the mix moist and promoting wicking action and so on. My understanding has been that when the reservoir's almost empty and the pellets are nearly dry it's time to re-water. (That's about right, no?)

Perhaps I wasn't watering correctly in the past, but with the old batch of PA I would notice that when the reservoir was almost empty, the pellets were nearly dry on the sufrace--it would coordinate very nicely. Now, with the new bag of PrimeAgra, when the reservoir is almost empty the pellets are still wet on the outside. I'm wondering if: a.) the PrimeAgra is not absorbing up the water into the heart of the pellet like it should and the water is staying on the surface of the pellet or b.) the pellets are taking in water, but at a greater rate than they used to and are therefore drying out more slowly.

If the pellets are wet but the reservoir is empty, should I be watering?

[Brooke]

I can only give you my experience with Prime Agra, both the old and the newer pellets.

My pellets never totally dry out on the inside and the moisture is visible through the containers even when the reservoir is dry. The very surface of the pellets do dry out because of air movement around the area.

Sometimes a pellet the size of the drainage hole obstructs the drainage or I have algae build up in the holes. I poke it to move the pellet and scrape the algae off.

Every oncidium family I have moved to s/h loves it.

Some phals love s/h and some I have almost killed. Phals with a heavy dose of mottle leaved species in their background rebel because they like a drier growing environment.

I have never tried to grow any type den in s/h so I have no opinion - for once :>)

Brooke

[NancyG]

I have dens, catts, and phals in S/H and just as Jenny and Janet have said I have to clear the holes at the sides to clear mineral build up. They all seem to love to S/H culture.

NancyG

[NicC]

Lissbirds,
Do I understand that you block off the drain holes in the s/h pot? That is not advisable since that is the only entrance for air to get into the pot. It also allows more water to remain in the pot than desirable. The techniques, as I understand it, is to flush water or solution into the pot until it reaches the top then allow to drain to the holes, the rest of the pot being the reservoir. you redo this once the reservoir seems empty. By that time, the topmost pellets appear dry but if you were to dump the pellets, the most central ones would be perceptibly moist.
If you are blocking the drain hole stop and see what happens.
Nick

[Lissbirds]

Originally Posted by NicC

Lissbirds,
Do I understand that you block off the drain holes in the s/h pot?

No, I'm not blocking the holes of the pot off. That would defeat the whole purpose of S/H. What I was saying was that the holes in the new pots I bought recently seemed a little smaller and closer together than the older pots I have around.

I'll clean off some of the minerals from the holes and maybe punch out another. I'm thinking I might set up a little fan for some air movement and see if that helps with the surface pellets not drying out. The newer PrimeAgra does seem to be holding moisture longer. It would normally be about a week for the reservoir to dry up and now I'm noticing about 1/4" of water in the reservoir after a week.

Brooke, your insights were very interesting. I just repotted a phal from S/H to a coir mixture today and noticed that the majority of the roots were rotted. I'm wondering perhaps also if I've been overpotting? I put it in a smaller pot and we'll see how it does. Maybe S/H leads to rot if you overpot...? For my S/H orchids I'll watch my watering more carefully and maybe repot to smaller pots to see if that helps....

Thanks all!
--Melissa