My cactus is seven feet tall. I've had it for about 20 years. There is more brown color at the base and up two of the stalks but it continues to make new baby leaves all over. It is in a pot that is 8 inches across. I'm concerned that it might need to be repotted but there is no way I can lift it. Also I wonder if it's too dry or too wet? It sits by the window that faces south and a large picture window on the front wall faces east. Please advise.
A cactus needs replanting at least every four years to replenish the soil. Yours is probably also root bound at this point. If you don't give it an annual feeding then you need to repot every couple of years just to put in new soil. Once it is repotted wait to water it again until it has had time to adjust to being handled. For a cactus that size you and your recruited help will probably want to wear heavy leather gloves and gently loosen the soil around the edge of the pot with a dull blade to allow you to tease it out of the pot. You can also wrap the cactus with layers of newspaper and secure with twine to protect yourselves.