Plants grow whenever they create more energy during photosynthesis than they use during respiration. Your Ficus elastica SHOULD be growing because light intensity and duration (day length) are at max on June 21. That it isn't growing is a symptom that at least one cultural condition is beyond the limits the plant is programmed to tolerate. If you're watering when the top inch of the soil is dry, you're almost certainly over-watering. In a pot that's 10" deep, the top inch can feel dry to the touch while the bottom 6" or more is completely saturated. This kills fine roots that do all the plant's heavy work insofar as absorbing nutrients and water. When fine roots die, the plant gets a chemical signal to halt top growth while the plant regroups and regenerates new roots to replace those killed. About the time an abundant oxygen supply returns to the soil, you're watering again. This establishes a cycle of root death and regeneration during which top growth is halted. That the plant is variegated adds to the issue because a variegated plant isn't as vigorous as it's green counterparts; this, due to the reduced level of the pigment chlorophyll, which is an important part of the process of photosynthesis.
The fix to that specific issue is as easy as monitoring your plant's moisture needs using something other than your digital device (finger). I'll leave something about using a "tell" to "tell" you when it's time to water below my comments.
Very often, nutritional deficiencies limit a plant's ability to grow at a normal rate or cause abnormal growth. While fertilizer isn't "food" for the plant, it does supply the building blocks plants need to grow. A full complement of nutrients is also required to keep plant functions and processes orderly and balanced. If you're watering correctly, so you're wetting the entire soil column and flushing the soil as you water, you should be fertilizing in summer about every 3rd or 4th time you water. In winter, every 4th or 5th is adequate. It makes better sense to link the frequency with which you fertilize to the frequency with which you water rather than the calendar, which provides an arbitrary yardstick. Foliage-Pro 9-3-6 is my go to product for the more than 45 ficus I tend, as well as for all my other trees. It's a superlative product.
When you water, do you allow water to collect in the attached collection saucer and be reabsorbed by the plant? Are you able to give the plant more light? It wants more.
Using a 'tell'
Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need plenty of air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support the kind of root health most growers would like to see; and, a healthy root system is a prerequisite to a healthy plant.
Watering in small sips in order to avoid over-watering leads to a residual build-up of dissolved solids (salts) in the soil from tapwater and fertilizer solutions - which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma and creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor.
In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water.
Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'.
One of the most reliable methods of checking a planting's need for water is using a 'tell' (more reliable than a 'moisture meter'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16" (75-85mm) works better. They usually come 48" (120cm) long and can usually be cut in half or in several pieces, depending on how deep your pots are. Sharpen both ends of each tell in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell's tip comes out nearly dry. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue.
Al
