It does look like nutrient deficiencies, which have the twin benefits of being slow and correctable. The interveinal yellowing, where the veins stay green, is more likely magnesium than iron... but the real way to tell is where it's happening. Magnesium starts at the bottom, iron starts at the top. The pictures make me guess it's the former; you could mix up a tablespoon or so of epsom salts in a spray bottle and spritz down the plants, and see whether the leaves color up again. The yellow leaves probably are nitrogen, and a light foliar feed is very unlikely to give them too much nitrogen. Spray them down with fish emulsion and see if they green up. If they do, start giving them light doses of nitrogen regularly. Clay soil can be very rich in just about everything... except nitrogen; your amendments weren't with anything that would boost that N level for any length of time, particularly if the chicken manure was old. Best of luck -- the plants should be fine once you can give them what they need. --Alison

Yep, it's definitely dryness response... I had forgotten to water mine, and that's what happened. Causes can be being rootbound, drop in humidity, and change in environmental conditions. Its certainly not scale, mealies or spider mite. As always, look at it with a jewellers loupe, or magnifying glass... As a keen gardener, I always carry a loupe when doing my indoor/outdoor rounds. This particular phenomenon is a sugary excretion - if not noticed quickly, it dries into a sticky crystalline spot, and leaves a transparent spot on the leaf underside. I have cleaned it off with soapy water, and a fresh water wipe afterwards Any little bugs will have been attracted to these sweet secretions, they are not the cause.

NEVER put a houseplant accustomed to low light outside in direct sun .. EVER ... if you want to take things outdoors.. you have to harden them off to new light levels.. by taking them out to full shade for a few weeks.. and then slowly working them into sunlight... if it is the type of plant that thrives in sun ... the further south you go.. the more important this rule is .. and that is why above they asked where you are.. big city name ... as long as the leaf has any green.. it is converting light into energy .. so regardless of how bad it looks.. leave it on the plant until it yellows and browns.. and then cut it off .. ken ps: i think of orchids as hanging on trees in tropical forests ... yeah i know.. its a generality ... but that thought makes me think to myself... they are never in full sun ... of course im sure there are exceptions in the greater family ... but if you are searching those out.. you ought to know all about that.. check this out: https://duckduckgo.com/?t=ffsb&q=orchid+natural+habitat&iax=images&ia=images

If this plant can go more than 2 weeks between waterings w/o wilting, it's almost a certainty that there is a lot of potential for growth and vitality left lying on the table; and, mixing perlite into the soil does very little to improve drainage or aeration. Perlite's main attribute is, it displaces soil that would otherwise be filled with water after a thorough watering. Let's say you have a gallon can filled to the top with your soil (before the perlite was added). Between all the fine soil particles, there is some air. Incorporate a marble into the soil. What happens? A volume of soil and air equal to the volume of the marble is displaced and spills out of the pot. Now do that 500 times, so you now have a can of soil that's roughly half marbles and half your original soil. The 2 things that jump out at us are 1) the roots cannot grow into the marble, so the amount of soil available for root colonization is now half of what it was. 2) The amount of air in the gallon of soil + marbles is half that of the gallon of soil. So what is the net effect? By adding the marbles, you simply reduce the amount of soil the plant can actually grow in . Perlite is no different than the marbles, except that, the rough surface of the perlite does add a small amount of aeration in the immediate vicinity of the particle; however, since it's impossible for the particle to provide more aeration than the volume of soil it displaces, the o/a volume of air porosity in the mix of your soil + perlite decreased, and will continue to decrease on a per volume basis until there is so much perlite in the mixture there is no longer enough fine particles from your mixture to fill all the air spaces between the perlite particles - the 'threshold proportion'. From that point on, when perlite is coarse and the overwhelmingly large fraction of the medium (>80%), air porosity increases quickly. You can see this threshold effect clearly by starting with 2" of water in a jar. As you add marbles to the jar, the volume of the mixture decreases, but the air porosity remains at 0. If we keep adding marbles, at some point there will not be enough water to fill the very large spaces between the marbles, so at that point, the threshold proportion, air porosity increases rapidly. The take-away is, if you want to take advantage of the significantly better opportunity highly aerated and fast draining media offer plants, it's essential to start with a large fraction of coarse material, and limit fine material smaller than 1/10" to being used as a way to adjust water retention of the medium to something you are comfortable with. If you had a medium that required watering every day, your plants would love it, even if you wouldn't want to tolerate the extra effort. I don't want to confuse you with informational overload, but I do want you to have a sense of how important growing in a medium that doesn't fight you tooth and nail for control of your plant's vitality. If you like, we can talk more about how to make or find a good grow medium. ****************************************************************************************** Your plant should be watered before it becomes "stone dry"; and, if you really ARE allowing it to become that dry, it would show signs of wilting. If it's not wilting, it's not stone dry. A good way to determine proper watering intervals is by using a 'tell'. 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 leads 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. It 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'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends 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 comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue. Al