cwhitt said: My big pot that has several cactus in it does not have holes, but does have cactus mix in it. It sits next to a north facing window with light, but not direct direct sun. I only water it a couple of times, maybe twice, in the winter, and then maybe only once a month in the summer - I do not soak it as there are no holes in the bottom. I have lost 2 cactus - both a heartbreak. One was so tall it touched the ceiling, in a huge pot. But unknown to me, my cat started using it at a litter box and it turned to mush. 
I was devastated. The other cactus, was about 3 feet tall, and sat close to the litter box, but the top was filled with pine cones so my cat would not use it. However, the dust from the litter seems to have strangled it. I had dusted it every now and then, but then forgot for a while. Live and learn. 
I have no cactus plants near the litter box any more, and pine cones in the top of the pot really solved the other problem. I probably under water, but have lost nothing else, so that is good.
Having no drain holes in a plant container has always been a slow death sentence to any plant. Aside from overwatering, accumulated/unflushed salts remains in the media which further damages the plant in the long run. But it is a good learning phase, at least now you know why you must use containers with drain holes.
I have seen other growers that use containers with no drain holes, but they use no soil, just straight pumice or perlite, and water is really just a bare minimum if and when they do water the plant. So it is doable but got to be very disciplined in watering.
Also, north facing window is a weak light source..next time, best to position them by your east, west or south facing window.
