Vanda seedling light requirements
 

As the title states I’m trying to determine how much light my new Vanda seedling needs. I’m just getting back into orchids after many years, but I’ve never had a seedling before. I understand that Vandas like light, but I’m not sure how much light this young seedling is used to do I don’t want to stress it anymore than it already is from shipping and new environment.

The seedling in question is a Vanda coerulea supra with ~10 cm leaf length (no idea of actual age) that was delivered on September 7th. Right now I have it set up in a room with a south facing window with the conditions being between 65-85 degrees and ~60% humidity. I have grow trays and a humidifier so I can bump up the humidity if needed, but I prefer not to if unnecessary.

When this Vanda and a Laelia purpurata arrived at first I had them backed away from the window about 5’ and I left them this way until this morning when I installed a light filtering curtain. I tested the light around noon with the curtain up and plants moved close to the window which measured around 1200 footcandles.

Is this too much shading for this seedling? My plan is to monitor and gradually increase the light levels, but I’m unsure exactly what should be the starting point and how fast I should increase the acclimation process. I’m also concerned that such little light may be insufficient for the near flowering size Laelia.

Any advice would be greatly appreciated. I just don’t want to over-stress or burn this seedling.

I think that you're on the right track. Increasing light slowly and gently. As summer turns to fall, the sun will shift south (giving more hours of light relative to day length) but lower sun angle (and shorter day length). Consider another factor - light duration - as fall turns to winter. Over the short-day portion of the year, you may want to factor supplemental light into your growing environment. With good natural light for a significant part of the day, doesn't have to be fancy grow lights. Full spectrum LED would be fine (cheap is fine). Add a timer, so that you can give the plants good light 12 hours a day or so and I think that they will benefit.

Thank you, Roberta. I actually have a T5 light I got from hydrofarm years ago that I need to get out of the garage. I plan on using that this winter to supplement as you suggested.

Do you think that 1200 footcandles will be enough light to harden the plant? I will likely check with orchidweb next week to get a better idea of just have hardened this seedling is

Since I don't measure light (but live in an area where I can depend on Mother Nature all year, my issue is just not toasting things) my advice would be very qualitative. I suspect that you can increase the light a bit, both of these are rather high-light species. Given that you're growing indoor, and not at the peak of summer, you probably don't have to worry about increasing light too much. In general, fall (and early spring) are great times to introduce plants to the light, since it is pretty gentle. (Getting things adapted in the spring is more critical, so that they're ready for the long days of summer. Now, no worries)

I don’t typically measure light either. I’ve always just used the hand method, but I decided to download an app to give it a try. Without the curtain the meter shows the light being around 5800 fc and with the curtain around 1200 fc. I think that I could always switch to a thinner shear curtain to increase the light levels. They are fairly cheap so I will pick one up then test it to compare with the thicker light filtering curtain.

Both should have yellowish leaves. Increase light gradually so they don't sunburn. Both would be fine outdoors in your summers in dappled light.

Yellowish? I thought that just a shade or two darker than a Granny Smith was the norm.

Young Vanda seedlings do fine with light similar to young Cattleyas. That would translate into 2500-4000 foot candles.

Once the plant is mature, and you want it to bloom, you need to give it 3500-4500 fc, and if possible put it outside into full sun (with a week in shade to harden) once night time temps reach 55F. Growing it in full sun, you will have to water daily (I use an electronic timer & sprinkler to water twice daily here in NJ).

Thank you. I think I have the lighting worked out. The season is changing so I have it behind a sheer curtain now.

The seedling arrived in sphagnum moss. I don’t really want to stress it anymore by trying to change media. Should I allow the sphagnum to fully dry between watering or just approaching dryness?

I grow all my Vandas (about 75 plants) in:
3" - 4": Net pot
6" & up: Octagonal basket
but always with a spaghnum/bark mix (about 4:1). I try to water before they even approach dry, as it is difficult to rehydrate spaghnum once it dries out.

In nature, Vandas grow in regions with monsoon rains. It rains 2-4 times a day for 4-6 months. Thus, plants are doing best with fairly constant moisture.