Christmas Cactus Soil Won't Dry Out!
I will try to give as much detail as possible to help describe what is happening. First, some background: our Christmas Cactus flowered for the first time this past winter! Though we've had it for a few years, this was the first year we were able to provide adequate lighting/temps in the winter months (on an indoor, but unheated, landing with a west window). It was beautiful but seemed to take such a toll on the plant that I will probably never let it flower again, if I am able to keep it alive.
Up until it flowered, I would water when the top of the soil was good and dry to the touch; this was happening about every three weeks in winter. Many of its flower buds dropped, but a few did remain on the plant long enough to open. After flowering, the plant dropped maybe 5% of its leaves and looked a bit shriveled. The biggest change was the soil; it just would not dry out & always remained damp to the touch (not soggy, just damp)! After a month or more it would just be looking shriveled so I would give in and water it anyway.
By April the landing where it sat had gotten hot, humid & very sunny, and the leaves had turned a very pale green and were drooping. I repotted into a mixture of half cactus soil half perlite and moved it into an air-conditioned room where it would have cooler temps and indirect sun instead of direct as days got longer. The color returned somewhat and the leaves got firmer but never back to 100%. The problem is that the soil STILL will not dry out! It can go three weeks and STILL the top layer feels damp to the touch, even though the leaves start to droop and feel flimsy again. (Watering seems to help the leaves firm up and regain some color, though this could be my imagination.) I repotted April 16 (& watered it), then watered on June 7 and again today, June 30. It has started to gain a bit of new growth since the repotting, and it doesn't really LOOK sick, but I can tell it's not 100% healthy. (Mostly it's the soil bothering me; I have had plants die from overwatering in the past but I have such a hard time holding off on watering until the soil dries when the plant seems to be begging for it! Should I just be ignoring the drooping and waiting for the soil to dry?)
A note: it has always been used to being in a large pot with at least a four-inch radius from the plant stem to the rim of the pot. The pot I just put it into was about three inches deeper than its old pot; I bought this because when I repotted it a year previous, the roots were everywhere, curling up at the bottom. I was very disturbed when I repotted this year and saw the root system had shrunk considerably and wasn't even filling the pot, nothing like it had been the previous time I repotted it. If anything I should have put it in a smaller pot but didn't have one available.
Why this sudden change in the soil after the flowering, and what can I do about it? If the pot is the problem, can I repot a second time so soon without damaging the plant? I did have several leaves fall off when I repotted which are now in their own small pot and growing like crazy. If I need to repot, what size pot is recommended (how much space should the roots have; how much distance from stem to rim)? Could it be due to something else? I have noticed many small flies (gnat-sized) living in the pot and running all over the plant; could these be harming it? (It picked them up when it sat next to our pitcher plant, which attracts these flies.)
Thank you for taking the time to read my long story, and thanks in advance for any help you can provide. It will be much appreciated!