I have been trying to grow a pair of lemon saplings (from seed) with much care as to not over water. I previously tried to grow some from seeds and several unfortunately did not survive (due to my novice green thumbs overwatering) and 2 more were given away. I have looked all over the internet and have not had very much luck. My previous deceased plants died of root rot so I have become somewhat familiar to its unfortunate signs and symptoms.
These 2 saplings have grown from your run-of-the-mill generic miracle-gro potting soil, as I live in a very small town and was all I could find. I recently purchased a water/ph/light meter to help me with watering etc. as well as a fertilizer (Jobe's Organics Fruit & Citrus Tree Granular Fertilizer 3-5-5) I ordered online, which recieved and mixed into soil yesterday. They currently live in their own 12" plastic pot and i water them every about 10-14 days. Since doing more research online I have found that the conditions I am providing may not be sufficient. I currently live in south texas where usually we get heat of up to 100-105Fº (38-41ºC), because of this I usually leave them indoors by a window which seemed to do them well as leaves seemed to be coming in and looked perky. We have recently been having cold and gloomy days for weeks on end(light drizzle with temperature from 45-60 ºF or 7-15 ºC) and have not moved them from their spots; Today I saw online wrapping pot to help keep warmth could help in these cold conditions so I wrapped the pots in a few shirts each.
This week I have noticed about 50% of one saplings leaf fall, without any warning, and at first glance fallen leaves show no signs of distress. The other sapling has only dropped a single leaf in the same fashion. Most recently have begun to notice what looks like burn spots on a number of leaves on both.
Can someone please point me in the right direction on how to save and help make these 2 saplings thrive. The more detail the better please, I just don't want my ignorance and lack of experience to be the cause of death of these precious lemon saplings. I have looked into possible changing potting soil to cactus/citrus potting soil something like this possibly but also found that other things should be mixed in like sand, mulch, worm castings etc. and honestly it just goes right over my head:
I am trying to grow them because my parents have just moved and sold the childhood home where I was raised and where the original lemon tree resided. So many great memories came with that tree so in a way being able to grow and plant these at my future home will allow me to keep having great memories and quite possibly share some with my future family.