Phalaenopsis with a wrinkled leaf

[gul]

Hello,
At the end of the spring I cleaned the rotten roots of my troubled orchid and put it in water treatment for a few weeks. During this process it produced a basal keiki and two new leaves. Then in accordance with the advice from this forum I repotted it. It continued thriving and produced new roots in the open air throughout the summer and its keiki continued growing, too. I water it approximately once a week since I can observe water drops on the sides of the pot for a long time. I fertilize it once in two weeks (I use half of the recommended amount of fertilizer). I live on the Black Sea coast so the weather is warm and humid here and I plan to keep my orchid in the open air until it is too cold at nights. My problem is that the oldest leaf of the orchid has began to wrinkle and the rapid growth of the keiki seems to have stopped. There also seems to be greenish colour at the bottom of the pot suggesting algae formation. Does all of this indicate a watering or any other problem? Should I repot my orchid to get rid of the algae?

[Dimples]

Algae isn’t a problem. Light + water and nutrients = algae. It won’t hurt the plant. A plant outside in your area likely needs water more than once a week. The wrinkled leaf is a sign of under-watering, as is the stalled growth. You don’t need to wait until the pot is completely dry. Phal roots can stay damp so long as the medium is airy/chunky. Increase your watering frequency and it should improve.

[estación seca]

In addition to not enough water, it may also be getting too much light. Phals are shade plants.

[gul]

Thanks for your enlightening replies. I keep the orchid on the windowsill in an open balcony. Most of the time it is in shade in the open air but it gets direct sunlight towards evening for about two hours. The plant had only a few roots when I repotted it so the bottom part of the pot contains only bark and does not dry as quickly as the upper part. And this misleads me into thinking that the plant has enough water. Since I have previously had root rotting issues due to over watering I am afraid of it happening again. I will have to try to find the balance between over and under watering. I will water it more frequently (twice a week) for the rest of the summer and take it indoors for the hours it gets direct sunlight and monitor its reaction.

[Dimples]

Fresh, high quality bark that’s the correct size for phals (eg. somewhat chunky) is almost impossible to overwater for the first few months in your situation (outside, warm, bright). If you have mid-low quality bark, it will start to absorb/hold water sooner, but unless you mix sphagnum moss or another water holding material into the pot, you can probably water every other day while it’s outside. Especially since the roots are only in the top half of the pot, that’s the part of the pot that dries out first.

If you give it water more frequently it may be able to stay where it is, but direct light isn’t strictly necessary for phals.
High light + drought = stress
High light + enough water = growth

[PuiPuiMolcar]

It's quite common with Phal outdoor because these are low light orchids. Is your area windy?
judging from your information of location, heat + windy = rapid transpiration loss of water.

or it could because of the trapped heat intensified by mirrors without any ventilation to cool off the leaves.