Browning new leaves on Phragmipedium

[Dalachin]

What is going on with this Phragmipedium fritz schomberg? I just noticed the tip of the new growth is brown and sort of soft. The main growth has a brown spot too, has been like that for awhile now. I water it 2-3 times a week and the pot sits in 1 inch of water. I just water the medium, not the leaves.

[estación seca]

What water are you using? Fertilizer? What are your temperatures and relative humidity?

[Dalachin]

Once a week I fertilize w k-lite 100ppm in collected rainwater. During the week I water with tap water, ph 7.6 according to city data, all the water loving orchids get tap during the week. Generally 70 degree days and 65 nights, 35-40 percent humidity… although it is near a window and temps might have been in the low 60s at night. I have shelf where I grow my phals that is in the 80s and 40-60% humidity, but I thought the Kovachii hybrids preferred cooler (there are 4 on this windowsill, only the fritz is showing stress).

[Dalachin]

It was cold last night and I moved the plants off that windowsill and put a thermometer there and it was down to 45. So it is likely that some other night recently it got too cold for that new growth. Guess I need to figure out how to improve insulation in that area… or maybe I should just try growing it warm on the tented shelves.

[estación seca]

How much dissolved solids in your water? Does your water leave white marks on glass when it evaporates? They prefer water with very low dissolved solids.

I don't know the lower temperature tolerance.

The brown spots look like something happened to the plant a while back. Any chance it was very dry for a while?

[Roberta]

Originally Posted by Dalachin

It was cold last night and I moved the plants off that windowsill and put a thermometer there and it was down to 45. So it is likely that some other night recently it got too cold for that new growth. Guess I need to figure out how to improve insulation in that area… or maybe I should just try growing it warm on the tented shelves.

I think you might have found the problem... many Phrags are not all that cold-tolerant, 45 deg F may be pushing it - and maybe even colder next to the window. (Some Phrags are OK with it, some aren't...Phrag kovachii comes from relatively high elevation and so should be OK with temp, the other parent Phrag besseae definitely prefers warmer. In the case of Phrag besseae, learned the hard way.) So it is probably a marginal situation.