Maxerillia Tenuifolia with Yellow Leaves
 

I am so happy, my Max. Tenuifilia is flowering. But I don't know why some of the leaves are yellow.

The yellow leaves do not have a flower - so I'm guessing they are older.

Also, my winter temperatures are pretty chilly - down in the mid-50s and highs in the mid-60s F. I was worried it was getting too cold, so I placed it in a seed mat.

Any ideas on what causes Max. Tenuifolia leaves to turn yellow?

How are you watering, and how often? What is the potting medium?

Yes. I've been delaying potting because I've read these orchids don't like re-potting. I water once a week. I'm not sure what the potting media is. It's tightly potted in the green plastic pot it came in. The pseudobulbs are nice and fir.

Those temperatures should not be a problem. (My Max tenufolias live outside, they have experienced winter temperatures below 40 deg F, currently nights are in the mid-50's F and days in the mid 60's F. Summer will show up eventually, but it has been cool and they are thriving. ) Your heat mat may have caused the plant to dry out much faster - so if you heated the roots and didn't increase the watering, that might be causing some leaves to drop prematurely. (It's one of the strategies that orchids have to avoid desiccation when water is scarce). This species doesn't like to dry out completely, so "damp" is good. Consider increasing the watering frequency. Once it stops blooming, you can take it out of the pot and take a look at the roots as well as condition of the medium. If in good condition you could just move to a slightly larger pot and fill in with more medium. If the medium shows signs of breakdown, you could rinse off what comes off easily, but don't try to get rid of what is stuck to the roots. Just leave it.

Thank you for the very helpful
feedback.

I'm glad to know it wasn't the temperature. After it finishes blooming, I'll gently repot it.

I listened to a webinar on Maxillariella tenuifolia where the host suggested growing these orchids in sphagnum moss and hydroponic mesh pots. What do you suggest for indoor growers?

For almost all plants the specifics of pot and potting medium don't matter at all, and there is no magic combination. What matters is giving the roots what they need. How to do that will vary with your growing conditions. People in southern Florida struggle with high humidity and high rainfall. Here in Phoenix we have low humidity and low rainfall. The best potting combination for me would not work well in southern Florida.

Most orchids we grow are epiphytes, growing on trees. Their roots need lots of air. Some, like Max. tenuifolia, are accustomed to being moist to wet almost all the time. Others are accustomed to some drying from time to time. So for this plant, use something that has air spaces, but water it so it never dries completely.

People use sphagnum successfully. They also use fine bark mixes. Unless your ambient humidity is high I would think a net or clay pot to be counterproductive because medium will dry out faster in such pots. There are even OB members who have written they stand this plant's pot in a dish of water during warm weather because otherwise they can't give it enough water.

I know that's not exact advice because it will depend on your temperatures, humidity and how much time you have to check on and water the plant. But I don't think many people can get away with watering a Max. tenuifolia just once a week. Whatever you choose, be sure it has plenty of aeration, and you keep it always moist. That is advice for this plant - other orchids are different.

Based on the needs of the plant, this sounds like a viable potting scenario. There usually are multiple ways to meet an objective. In this case, you want a medium that retains some moisture, and also provides lots of air to the roots. this approach works, but you don't have to go out and buy special pots. A lot of our members use the semi-hydroponic system (developed by Ray, one of the frequent contributors to the Board. Free Info - Semi-Hydroponics ) This may work for you too, and give a low-maintenance way of managing this (and a lot of other) orchids. Check out the Semi-hydroponics Forum.

Thank you! I'll keep your advice when I repot it! 💚

I have had mine many years (since the project)
And have repotted twice as well as given family some growths. (you can see from photo)
I have found that The best way to water it in my conditions, is once a week. It sits permanently in a plastic container which I fill with water and it sucks up the water at it’s leisure…. I very rarely have yellow leaves and it blooms more and more every year. here are 2 photos just taken of it.. needs a repot! :)

Thank you for sharing! Your orchid looks lovely. So, you water the outer plastic pot once a week.