new root tips die when they touch LECA

[razka3]

So I bought this Lc. few months back... and most of the roots were rotten. So I figured why not raise it using S/H culture. So I stuck it in some LECA and watered as usual, did everything correct (I assume). So I start seeing 5 new roots coming out a few weeks ago! Thought to myself that's great... they will take right to the LECA and the s/h environment and will grow like crazy.

Instead to my amazement, during the last few days when the roots came into contact with the LECA the green root tips turned black and stopped growing. The new roots now look awful.

The weird thing is that this is also happening with two other small plants I have put in s/h culture... the new root tips instantly die when they hit the LECA.

And yes, I did soak and flush it prior to using. Am I doing something wrong here? Maybe I should just grow this in bark mix?

[quiltergal]

Frank, I had a similar experience with an Slc. I had it in s/h for 9 months. It grew 5 new roots but instead of diving down into the LECA they were growing straight up and away from it. Eventually they shriveled up and died. I finally took the plant out of s/h and am trying it in coco. Maybe it's just this type of hybrid that doesn't do particularly well in s/h. If it starts rooting in the coco I'll post back here. I have 2 Onc. and 2 Phals in s/h that are doing just fine. Not sure what the deal was with this one.

[Ray]

Sounds to me like one of two things is happening:

1) The LECA was either not prepared properly, or has absorbed (and concentrated, especially at the surface) some minerals that the roots don't like.

Assuming you did prepare the medium well, try using just water without fertilizer for a while.

2) Your conditions and watering frequency are such that the LECA at the surface is drying rapidly, so the medium is actually extracting water from the root tips.

Water more.

[razka3]

Sounds like #1 part (b) #2 are the probable culprits... Thanks for the tips Ray!

[Ray]

I have never seen that, but I do grow in a greenhouse with pretty high humidity, so the LECA is usually fairly uniformly moist throughout the pot.

[razka3]

My humidity is never below 60% now... but the LECA just won't seem to hold the moisture above a few inches from the bottom. Watering more often would probably resolve that issue, it's a shame I'm starting a really busy next few months, won't have time to water often.

Maybe I'll try plugging the holes and letting the LECA soak for an hour, then letting it drain. Might help some.

[Des]

In addition to what Ray has said, make sure that the plant is well anchored in the pot , so the that root tips do not rub against the Leca , if the plant moves the root tips are easily damaged,will turn black and will stop growing.The plant will then then try to send out another root and the tip will once again be rubbed off on the Leca. So that you end up with a plant that has lots of short roots. So make sure that the plant cannot move untill it anchors itself.

[Des]

It is also possible that you have too much air movement across the top of your pot , drying out the top layer of Leca exacerbating your problem (been there done that )
Took me a long time to figure it out !
Hope this helps
Des

[jamesgang]

I am adding new plants from time to time --right now mostly oncidiums and phals and I want them to live in s/h medium. So should I move them or wait to see new growth and then replant? Jim

[Des]

I always wait for the roots from the new growth to be about 6 to 10 mm long before repotting . I don't know about phals though,I don't grow them . The winters are too cold here and heating them too expensive.