dehydration in lava rock and aliflor

[ALToronto]

Originally Posted by bethmarie

What genera do you have in lava, Al?

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Catts, oncidiums and mature phals. Phal seedlings don't do well in it.

I also keep phrags in lava rock in less wet semi-hydro, with drainage at 10-15 mm from the inside bottom of the pots. I also water them every day, until water comes out of the drainage hole.

[AussieVanda]

All my angraecum's are growing in a lava rock mix. It is mixed with charcoal and polystyrene. All my lava rock is 20mm in size. 3/4 inch?

I water heavily every morning, on hot days a second watering in the afternoon.

Edit: I should also add that I am using plastic slatted square vanda pots. Sizes used are 150mm and 200mm. (8 inch and 10inch?)

[bethmarie]

Thank you all for your feedback.

I think the bottom line is I need to water more frequently. The grower that most of my lava-grown plants are in recommended once a week, but I think that's greenhouse-speak, since that's where all his growing takes place. In growing under lights-speak, it probably means more like every 5 days at a minimum.

[tucker85]

It's always a balance between water holding capacity and watering frequency. If you can water more often, that's usually the better choice. If your schedule doesn't allow for more frequent watering, you can increase the water holding capacity in several different ways. You can add a little bit of coconut husk chips or sphagnum moss to your mix. Another way to retain water is to stay with the same mix but to use a plastic pot instead of clay. Whichever culture practice you alter, do it gradually. Water a little more often or add a small amount of water retaining material. It takes time for orchids to adjust so it takes a while to know if the changes are achieving your goal. Good luck.