The leaves on my cactus are yellow and falling off. Why?
As I don't know your specific cactus, I can't say for certain... but for most cactus, this is caused by overwatering. Allow the soil of your cactus to dry out completely before watering.
My friend got a succulent, or like cactus, overflowing its original pot. How can you repot an overflowing succulent or cactus, which are too tight from its original pot, without destroying it and make some more out of its original one? What kind of soil do we need for that??? Thanks! Imee
The following article should be of some help to you: https://www.gardeningknowhow.com/ornamental/cacti-succulents/scgen/propagating-cacti-and-succulents.htm
Which cacti can survive winter weather--in the teens?
To answer this question, one would need to know which zone you are discussing. There are cactus and succulents that withstand very cold winter temps. Bear in mind that it isn't only temperature but moisture level that is important in whether or not a cactus or succulent is hardy. This link provides a partial list of cold hardy cactus and succulents: https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-7/cactus-plants-for-zone-7.htm
I got this cactus for my mom, and the people who sold the cactus to me said they glued rocks to the soil so the cactus won't sink in the soil. They used a polymer glue. I don't know much about plants. Is the cactus going to be okay? If so, why would someone glue rocks on the soil?
Generally, this is done more for aethetic appearances. Many people choose to remove these stones, especially when repotting. While there is nothing that will dissolve the glue well that won't hurt the plant, you can try to scrape or file away some of it, though you would be best leaving some of it there. Just remove what you can without damaging the plant. It is ok if some remains. After that, you can just care for the plant (or repot) as normal.
I have a potted cactus that fell. The top portion of it broke off and the top inside of the cactus is now exposed. If I leave the cactus alone, will it regenerate the broken portion? Is there anything I can do otherwise (such as cut the top part of it off cleanly)? Thank you!
It would likely be best to simply cut the broken piece from the plant, which will callus over and heal. The top portion can also be propagated to make another plant, if desired, rather than tossing it. Here is more information on that: https://www.gardeningknowhow.com/ornamental/cacti-succulents/scgen/propagating-cacti-and-succulents.htm
I live in a mobile home community in Las Vegas that for some stupid reason doesn't allow cactus to be planted in the ground! I have bought a variety of cacti all in pots from the garden centers. I have through much difficulty (ouch) replanting some in larger pots and lost some due to winter temps or overwatering or underwatering I guess. Haven't done any fertilizing. I had my cacti in my front yard, which for the better part of the day is in the sun. To avoid having to keep transplanting from pot to pot (of which I have lost some cacti due to lack of knowledge I guess), I was thinking of purchasing wooden box planters medium/large and planting my cacti in them. To me it seems that would be better than pots and slips past the "not in the ground (stupid) policy." Does anyone think this will work? And, if so, how many cacti per box based on a 24" box? Or should I just buy large pots and replant one more time (ouch!!!)? Any other suggestions (short of moving) would be appreciated.
Yes, the wooden boxes will work fine. Just make sure they have good drainage and that you mix some sand or other grit into the soil so it drains well. Cacti are often killed by soil that stays too wet and this will keep it from staying too wet.
I would like to grow cactus outdoors in pots this summer. Please give advice to type of soil, etc.
Potted cactus plants require a well-drained compost mix (two parts potting soil/compost, two parts sand, and one part gravel) or a cacti-specific potting medium. They should be watered with tepid water when their soil becomes dry. For more information on growing cacti outdoors, this article will help: https://www.gardeningknowhow.com/ornamental/cacti-succulents/scgen/cactus-landscaping.htm