Pine Seedlings In Winter

[ECMist]

Hello all,

I have some Rocky Mountain Pine (Pinus aristata) seedlings that I started in February and have been doing well so far. However, their needles have begun to change color, which I read is normal, but have begun to lose a couple needles of a yellow color and some needles have become purple. Is this normal, and should I eventually move them into an unheated garage under grow lights if temperatures begin to dip below freezing?

 

[ECMist]

Photos

 

[PA_Penjing]

In my experience, our part of the country is not very kind to pine trees. Our natives are equipped to handle the humidity and heat AND cold. But I have found that pine species from arid parts of the world don't love it here. I don't know Ellicott City at all but if you have Ozone and air pollution that's another damaging agent to the genus. If I'm not mistaken, pinus aristata is known for holding onto its needles for many years, so this could be a fungal issue or the result of a soil moisture problem. After taking a second look at your photo the dying "needles" might just be the juvenile guys that aren't equipped for the winter? the mature needles turning purple is fine

 

[ECMist]

Very much could be. I realized the soil could definitely be better now that they have germinated and are older, but I figured I’d best wait for spring to repot them at the correct time rather than risk upsetting them late in the season. Though, it’s strange that they were fine with the soil until it started to get cold…

 

[Wires_Guy_wires]

Pines can hold on to their needles for a long time of they need to.
When conditions are not great they can sacrifice old needles to feed the new. That's not always an issue but it can be a pointer that tells you something is off. Combined with purple coloration - which also just happens sometimes - I think "soil too wet" is a probable cause for both.

Getting them separated and into their own pots, with coarse soil medium would solve that issue after the winter.

I'm growing longaeva at sea level, and people told me it would never live past 5 years because of our high humidity and fungal pressure, but it's 7 years old now.
It took some soil adjustments like using straight up gypsum to help it out, but it's doing good.

 

[ECMist]

Would you have any recommendations for soil?

 

[Orion_metalhead]

Youre going to want to go with a mostly inorganic mix.. something like pumice, perlite, and lava or, if you can find it, pumice and lava with a small amount of akadama. Either way, something fast draining that wont gum up after a few years, as pines typically are repotted far less than deciduous. You need a medium that wont break down easily in the MD humidity and temperature swings. Ellicot is near baltimore (if memory serves me). I remember summers are often humid near the harbor there, as opposed to further inland near Frederick.

 

[Wires_Guy_wires]

I'm getting only crap akadama for the past couple years, so I'd go with pumice, perlite, (porous red) lava rock, and crushed granite, or a combination of those.
I added crushed limestone (2-4mm) to my longaeva soil because that's what it seems to be growing in natively.

 

[PerryB]

I'm not that far from Ellicott City, and I'm growing all of my pines in 1:1 pumice/ coco coir. This includes a 5 year old JBP, a yamdori Pinus pungens, and quite a few 2 year old JRP and JBP. I only water them every 2 or 3 days All are growing really well; all were outside last winter with pine straw mulch around them.

I am worried about the JWPs that are stll in nursery soil since it was past potting season when I bought them in late May.I already lost one due to too much watering. I planning on rain shield for the winter for the 2 that remain, but they will also be outside.