Semi-Hydro for a young vanda? and can terracotta pieces provide any benefit?

[itzi]

I'm growing a Vanda Boonyarit Spots, I think its a few years old, it has 4 pairs of 7-8" leaves.

I've been using some pieces of unglazed terracotta at the bottom of my vanda basket lightly packed with spanish moss in hope to help the roots stay humid for longer, and it seems to be working; They went from drying out in 2 hours under a grow light to 6 hours with the few terracotta pieces. I'm learning the basics of semi-hydro and I wanted to know if terracotta could play a part in this type of growing culture.

Are terracotta and LECA similar / the same? I dont think terracotta expands, but it definitely holds water and then "sweats" it out over an extender period of time. As a matter of fact, this morning when I soaked my basket I could even hear fizzing, which I later learned was the sound of air rushing out of the terracotta. Im not certain if my current growing method for my vanda will be my permanent one, as I'm waiting for new root growth and collecting data to decide what the best method for my situation would be.

I'm placing it under a SunBlaster F54T5-HO at about 8 inches away from the lamp, which gives it 6500-7500 lux, and using a conversion rate I found online, about 100 ppfd. In the morning, I soak it between 15-30 minutes with tap water and 25ppm N 20-20-20 solution. Humidity after watering jumps to around 50%, then dies down over the next 6-8 hours to 35%, after which I turn off the grow light to avoid desiccation of the leaves. It stays around 40%-30% till the next morning when I start the cycle again. Temps are fairly warm, around 85-70F the whole time.

I think this is alright for now, but I would like to move towards something that requires less upkeep and can be more easily scaled as I will likely expand my collection.

[Ray]

The only people I know that have been successful with vandas in S/H culture grew in extremely dry environments.

[estación seca]

I have a humid sunroom. Very small Vanda seedlings do better for me in S/H than in other media. What I really need to do is expand the area getting sprayed via a timed irrigation valve.

[Shadeflower]

It can be done but I wouldn't recommend doing it.

The thing Vanda's need more than other orchids is air around the roots.

Semi hydro restricts the air flow. The best I have achieved is semi semi-hydro ( ie half the pot filled, half bare root) but this also only works for hybrids.

For seedlings I find it great as it helps with watering but bigger Vanda's can store lots of water in their roots so weekly soaking works well for them.

What happens in semi- hydro a lot is that older roots don't acclimatize to semi-hydro. For fast growing cattleya hybrids as long as they are repotted at the right time this is not too much of an issue but for slow root growing orchids like angraecums and vanda's this can be disastrous. Some of the roots on well established vanda's will be several years old and will grow a bit more every year so losing all the roots in one year changing to semi hydro can severely set a vanda back.

With a seedling there aren't many roots to lose so not much harm acclimatizing it to s/h

With a bigger plant you have to ask yourself what is the advantage. Since they can store a weeks worth of water in their roots if you give them an hour long soak there is no need to worry about watering them that much.

On the picture I will add even though it is semi semi-hydro the roots don't seem to care for the lecca too much, in fact the first set ended up rotting, with a bit less lecca and more air flow the roots like the high humidity environment but generally the roots avoid the lecca as you can see not many roots have grown into it.

[estación seca]

A Vanda in Texas cannot store a week's worth of water in its roots.

[itzi]

Yup, even now in december the mid-day sun bears down at like 80-90F with nearly no cloud coverage. Right now my house is around 28% humidity. So I need to water often, unless I invest in a humidifer setup strong enough to raise my room to 60-70%, or a mini-greenhouse setup.

The semi semi-hydro reminds me of vase growing, and I can se the benefit in a glass vase filled partially with LECA and drainage holes drilled. I'm just worried more about desiccation through the leaves than anything, which seems to be my main issue. I feel like trying to raise humidity around the roots is a nil effort when the dry air saps it out of the leaves 24/7.

I know I need to be gentle with the roots on mine, especially because they're already not in perfect condition, so I'm not going to rush into anything. I just want a less demanding watering method for the future, because I'm very fond of vandaceous orchids and I would love to grow more.

[Ray]

FWIW, I have been successful growing vandas in mesh baskets of LECA. Holds water without becoming “soppy”, and remains airy.

That’s actually a nice property of the material - even when the surface has dried, the particles still contain a lot of water, which comes out as high humidity in the root zone.

I’ve seen S/H plants with dry reservoirs go more than a month without watering, but are still plump.

[itzi]

I was just looking up LECA methods for Vandas last night, I think thats what Im going to settle on. By mesh baskets do you mean the hard plastic ones with little square holes? Also, how would a clay pot + LECA go? I feel it would serve the same function, but Im worried it might get too cold.

[estación seca]

I think with your temperatures evaporative cooling at night would not be a problem. But I would use plastic to keep more water in the container and enclosed air. Go to what was formerly a dollar store and look at plastic bins.

[Ray]

These are what I was referring to.