The evidence of a physiological disorder called 'oedema', and the poorly formed new leaf point to an ongoing issue with too much water in the grow medium for too long. About oedema:
Oedema
Oedema (aka edema) is a physiological disorder that can affect all terrestrial plants. It occurs when the plant takes up more water than it can rid itself of via the process of transpiration. The word itself means 'swelling', which is usually the first symptom, and comes in the form of pale blisters or water-filled bumps on foliage. Under a variety of circumstances/cultural conditions, a plant's internal water pressure (turgidity) can become so high that some leaf cells rupture and leak their contents into inter-cellular spaces in leaf tissue, creating wet or weepy areas. Symptoms vary by plant, but as the malady progresses, areas of the leaf turn yellow, brown, brown with reddish overtones or even black, with older damage appearing as corky/ scaly/ ridged patches, or wart/gall-like bumpy growth. Symptoms are seen more frequently in plants that are fleshy, are usually more pronounced on the underside of leaves, and older/lower leaves are more likely to be affected than younger/upper leaves.
Oedema is most common in houseplants during the winter/early spring months, is driven primarily by excessive water retention in the soil, and can be intensified via several additional cultural influences. Cool temperatures, high humidity levels, low light conditions, or partial defoliation can individually or collectively act to intensify the problem, as can anything else that slows transpiration. Nutritional deficiencies of Ca and Mg are also known contributors to the malady.
Some things that can help you prevent oedema:
* Increase light levels and temperature
* Monitor water needs carefully – avoid over-watering. I'd heartily recommend a soil with drainage so sharp (fast) that when you to water to beyond the saturation point you needn't worry about prolonged periods of soil saturation wrecking root health/function. Your soil choice should be a key that unlocks the solutions to many potential problems.
* Avoid misting or getting water on foliage. It slows transpiration and increases turgidity.
* Water as soon as you get up in the AM. When stomata close in preparation for the dark cycle, turgidity builds. If you water early in the day, it gives the plant an opportunity to remove (for its own needs) some of the excess water in the soil.
* Put a fan in the room or otherwise increase air flow/circulation. Avoid over-crowding your plants.
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Saturated grow media and the accompanying dearth of oxygen that accompanies it limits a plant's ability to take up Ca(lcium), which must be adequately represented in the nutrient stream at all times if newly forming cells are to form normally. Even if there would ordinarily be an adequate supply of Ca in the grow medium, soil saturation prevents the plant from accessing it in the amounts needed for normal growth. Blossom end rot in tomatoes, peppers, and other plants, is most often caused by a physiological disorder that limits uptake of a sufficient amount of Ca, the result being abnormally formed cells with weak walls that collapse and spill their contents into inter-cellular spaces where rot then becomes an issue. Not the same as oedema, but characteristically similar.
If your pot is over 5" deep, and the metric by which you determine your watering intervals is 'when the top inch or two of the soil feels dry. You're likely over-watering, especially in consideration of the recent potting up. Once the area of soil not yet colonized by roots gets wet, it can take a very long time for it to dry out. I'm assuming you didn't do a full repot, which includes bare-rooting, root pruning, and a change of grow medium? If you have a 10" deep pot, when the top 2" of the soil column feel dry to touch, the bottom 6" of the soil might still be 100% saturated with water. It doesn't matter so much what occurs in the top couple of inches of soil insofar as moisture levels are concerned, as it matters what moisture levels are at the bottom of the pot.
My suggestion is that you discontinue the digital device (finger), and start using a "tell" to nail down watering intervals so they're consistently appropriate. I'd bet the ongoing battle you're currently having with your grow medium for control of your plant's vitality will end up in your 'win column'.
Is there anything else you have questions about? Fertilizing, for example?
Al
Q