Plants don't age in the same way we think of people aging. Age in people is a described on a chronological basis, where plants age ontogenetically. This might be framed as, the parts that have taken the most cell divisions to produce are the plant's oldest parts; so strangely, the most recent part of the plant (say, a new branch high on the plant) to grow is the oldest part of the plant. The youngest part of the plant will be found in the root to shoot transition zone. This juvenile part of the plant is also nearly always the most vigorous part of the plant. Plants pass through life stages until they end up at the sexually mature stage. At that point they are capable of blooming/fruiting. Whether they DO or not is complicated and not entirely understood. Blooming and other environmental reactions of most healthy plants are primarily influenced by day length (technically it's night length), but more than a few plants are triggered by other factors, like moisture availability, temperature, predation. Some plants even seem to have an internal 'alarm clock' that acts as a trigger to bloom. There are species of bamboo that bloom as infrequently as every 130 years and when the bloom occurs, all plants of a given genetic origin bloom simultaneously, en masse (all at once), and this occurs regardless of environmental influences. Now, that a plant is capable of blooms/fruit doesn't mean it will produce same, no matter how much we hope. The factors that limit a plant's ability to bloom are as complicated as those that trigger blooming. The plant's internal chemical messengers that limit blooming is first influenced by the plants ontogenetic age, but then by health, stress, stored energy reserves, a significant number of environmental factors, and sometimes seemingly no more than a built-in piqued obstinacy that can be more irritating than Justin Bieber or the Kardashians, if that's even possible. How do I get it to bloom? Keep it healthy and let it do its thing. You can search online - there might be some simple ways to coax it to bloom exactly whenever it feels like it. How old does it have to be? The only age important to plants is what growth phase they're in. They have to be old enough chronologically to have reached sexual maturity. This is also complicated because the (ontogenetic) age of the parent plant from which the propagule (that is now your plant) was taken has to be a part of the equation. Example - a hawthorn tree from seed needs to survive around 20-25 growth cycles to bloom; whereas, a cutting from a blooming hawthorn tree can be counted on blooming within a few years if its state of vitality has been generally good. Al

matt I don't know, but leaves usually shrivel and dry up if too dry. I don't use moisture meter (they are not that reliable, unless you have a better quality one); if I have any doubts I just stick a bamboo skewer deep into pot to check for moisture. Just checked my plant, there is 1 leaf that is yellowing - I am quite sure it is just old and is going to dry up and fall off. There are 3 big branches/stems on my plant, mostly 'naked', with leaves just at the top. It is constantly in bloom - I got it in 2012 and it never stopped blooming yet. It really needs to be repotted (still in pot & soil I got it in!), and also pruned, since there is no branching at all, and is getting too tall. Here is photo of 1 yellow leaf, and top of one of the branches:

It has long ago been proven putting rocks in the bottom of a container is a bad idea. Doing so raises the perched water table higher into the container and the tree's root system As to your soil test results, the nitrogen should be high, the phosphorous should test rather low and the potassium should be high. Below I have posted a link showing citrus with a potassium deficiency. https://www.google.com/search?q=potassium+deficiency+citrus&rlz=1C1OKWM_enUS900US900&oq=potassium+deficiency+in+citrus+leaves&aqs=chrome.1.69i57j0.27068j0j4&sourceid=chrome&ie=UTF-B AND https://www.yara.us/crop-nutrition/citrus/nutrient-deficiencies/potassium-deficiency-on-mandarin-citrus/

I've grown a Rabbit Tracks Maranta for ages and it's common for the old leaves to yellow/brown and die. It's also common for the entire plant to die off and go completely dormant for a short time in the winter. It always starts growing again in the spring though! :)