I have a Brook Cherry sapling planted from seed that has some browning/curling around one of its bottom-most leaves (leaf #1) and slight curling of its other bottom most leaf (leaf #2). The seed came from a Cherry Orchard outing where I proposed to my Fiance (she said yes :), so the seedling has very special significance for us and I'd really appreciate some advice about it.
I first noticed the tip of leaf #1 turning brown about a week ago. At the time, the tip of the leaf was quite close to the soil -- so close that I believe it may have been touching the soil at some point recently. When I noticed this, I removed some of the topsoil to give the bottom-most leaves more distance from the soil. About a week has passed since then, and the browning seems to be getting worse, progressing along the edges of the leaf. I've also noticed the the other bottom most leaf has started curling recently as well. I've included several pics below.
Some history: The seed had stratified in our refrigerator, and about 30-40 days back, I noticed it had sprouted, so I potted the seedling using some Miracle Gro potting soil I still had in a bag, planting it about 1.5 inches deep. Full disclosure -- the potting soil was many years old, but was still unused from the bag, and hadn't been used to grow anything else.
As well as watering every few days, I had also been occasionally spraying the leaves of the sapling with a water bottle every day or two. I stopped that when I noticed the brown tip, concerned that maybe it was causing it. I always use distilled water for watering and spraying because our tap water is very very hard. Until yesterday, I also keep it under an LED grow light for 12 hours a day. I've since lowered the brightness of the light and moved the light source further from the sapling, just in case that was a problem.
Also: I live in Southern California and have been growing this indoors.
Any advice? Should I prune this leaf, and if so, where and how do I make the cut? Or was using old soil my mistake, and if so should I repot in a different medium like peet moss? leaf #1 is a bit less than an inch from the soil now, should I remove even more topsoil to give it more space? Or something else? Thanks :)