What is your concern? The plant is Ficus elastica 'Tineke'. If you can rely on the meter for an accurate pH level, 7.0 is about the upper limit. 6.0-6.5 would be more desirable and can be achieved by using an acid-forming fertilizer like Foliage-Pro 9-3-6, which is very likely the best choice you could make.

Fertility and watering practices are inextricably intertwined. Ideally, you would water thoroughly each time you water, completely saturating the entire soil column, using enough water that at least 20% of the total volume of water used exits the drain hole. This type of watering ensures minimal build-up of dissolved solids (salts) in the soil and that the actual ratio of nutrients in the soil does not become badly skewed over time. You'll do better if you skip the water meter and use a tell made from a 1/4-5/16" wooden dowel rod. Insert it in the soil all the way to the pot's bottom and water only when the soil is nearly dry.

Tying your fertilizer applications to the number of times you have watered makes more sense than arbitrarily using the calendar as your guide. Fertilizing about every 4th or 5th watering during the dark months, and every 3rd or 4th watering during the long days of late spring - early fall is a good plan.

Your plant wants very bright light, 4,000 - 8,000fc. Light diminishes by the square of the distance from the light source. What this essentially means is, a plant 5 ft from a window gets only 1/25 the amount of light it would receive if 1 ft from a window. I have many species of ficus and all are grown in full outdoor sun in summer.

This is just general info. We would need to know what has you concerned in order to address the issue directly. Plants grow when they make more energy during photosynthesis than they burn during respiration. If your plant is not growing, it means the plant is using all it's current energy production, to keep it's systems orderly. Plants in this state are especially susceptible to insect herbivory and disease pathogens.

Typically, if low light is not the limiting factor, it will be inappropriate nutrition or a root problem, like soil compaction, root congestion, or a fungal root infection, but as of yet, there isn't enough information to reach a conclusion re root issues.

This link to Care of Ficus Trees in Containers might be helpful.

Al

What exactly is troubling you? I can't see anything wrong with the plant considering it is still quite a young cutting.

It isn't a mystery plant. It's been named above. Only a bot would call it a cactus. Flagged.

No mystery here, John. The plant is Ficus elastica 'Tineke'. It wants a pH 15-20x lower (pH 5.5 - 6.0) than 7.0 when grown in container media, and nutritional supplementation rates/timing depend largely on the amount of light it receives; however, it can't be said that any plants in the mulberry family (Moraceae), of which Ficus is a member, like low fertility levels unless they are grown under exceptionally low light conditions which no plant in the mulberry family prefers. They will do best (grow fastest) in a southerly window (in the northern hemisphere), followed by west then east windows. North exposure seldom provides enough light to ensure the plant's level of vitality is sufficient to ensure adequate defense against insect herbivory and disease pathogens.

They prefer a 3:1:2 ratio fertilizer (like Superthrive Foliage Pro 9-3-6). 2:1:2 fertilizers are appropriate for plants in very low light, but trying to find one with all the attributes inherent in Foliage-Pro 9-3-6 will prove to be an exercise in futility.

Al