Ask Alex, the Cactus Expert 2

-The Question and Answer Page
on cactus care-

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(Cactaceae)

Introduction

We have made this page as an answer key to questions commonly E-mailed to us. Look at the page for care for rotting cacti, sunburned cacti, learn the best time to re-pot a cacti. Find information on the featured Saguaro cactus.

Can you give me some general info on this plant?

A cactus is a unique plant that is commonly found growing in a desert habitat. It belongs to the family Cactaceae. Cacti are equipped with many adaptations that suit them for the desert life. Instead of leaves, from which water escapes easily, this magnificent plant has spines, which greatly narrow down water evaporation. The spines also protect the cactus from hungry predators such as birds. A cactus has short roots, which also minimize evaporation. A cactus is a vascular plant, meaning it can support itself while growing to amazing heights. The saguaro cactus can grow unto an astonishing 45ft. Probably the most amazing fact about this plant is that even in its harsh climate some cacti can survive over 200 years! These adaptations allow certain cacti to survive 3 years without water; a human can barely survive 4 days.
            Cacti reproduce using a couple of methods. One way is a vegetative reproduction: when for any reason a cactus branch falls off, it will grow into a new cactus. Cacti can also reproduce by using seeds. They form flowers that are eventually replaced by fruit (for some species) and seed.
            Cacti are used by both man and animal. Animals such as birds eat cacti and use holes they made as shelter. Burrowing animals make homes near roots since the soil has more moisture than common desert sand. People use cactus for water and food, though not frequent. Most humans such as I use cactus for décor and gardens. Many cacti such as prickly pear and golden barrel cacti make great houseplants. Some, like the Easter and Christmas cactus are used as holiday décor.
A cactus is good plant for everyone. It does not require much care. Some people even say that the less you care for them the better. This makes sense because in the desert no one helps wild cacti grow in the harsh conditions. You still must water them and give them sun and occasional feed. This page will give you instructions on indoor cactus care.
 

Rotting cactus survival guide

 I believe my cactus is rotting. What the prickly pear should I do?

I think my cactus is rotting? How do I know for sure?

My cactus is becoming brown at its base. Why? Can I still save it?

The second way to save a rotting cactus (that's rotting from its base) is to simply cut of its top. 
Using a sharp knife cut off the top of the plant.  Note that if white liquid pours out, the plant is not a cactus but an euphorbia. In that case, be careful! If the liquid comes into contact with sensitive places like eyes, mouth, etc. you may be harmed. It is toxic ! After that let is dry for a 2-5 days. Then place the top in another pot and plant it. If using the same pot, clean out the soil, so the cactus top won't catch its own disease. The cactus top will, after being planted, develop its own roots and will then grow as a normal cactus. For the first 2 weeks of the new cactus being planted water more frequently than usual. On Cactus expert page 1 you can see typical watering instructions.

My cactus is rotting from the top. What shall I do?

If a cactus is rotting from the top you need to act immediately before more of the cactus rots. Just like as if it is rotting from the base, carefully cut off the top of the cactus that is rotting. Dispose of the cactus top. As for the bottom, clean it with a spray to make sure it does not catch the top's disease. Change the soil unless it looks as if the cactus can't take a repot. The remaining cactus should now be healthy. After a few weeks of extra care, start caring for it as for a normal cactus. It will not grow a new top or increase in height but it will grow branches which will grow. I guess it is better than no cactus. 

Emails Q&A

Please note that the email conversations have been modified to pertain to the questions of a broader group

I have a cactus
However after watching it grow healthily for many years, with 2 house moves
and 2 re-pots it seems to be detraining. The base of the cactus is becoming
darker and darker. I Read on various websites this could be caused by the cactus
recently being re potted in a pot without holes in the bottom. If this is the case how
do I go about repairing the damage I have caused to the plant.

Featured Cactus: Saguaro

The Saguaro (Carnegiea gigantea) is a large, tree-sized cactus species in the monotypic genus Carnegiea. It is native to the Sonoran Desert in the southwestern United States and northern Mexico.

The magnificent Saguaro Cactus, the state flower of Arizona, is composed of a tall, thick, fluted, columnar stem, 18 to 24 inches in diameter, often with several large branches (arms) curving upward in the most distinctive conformation of all Southwestern cacti.

The skin is smooth and waxy, the trunk and stems have stout, 2-inch spines clustered on their ribs. When water is absorbed , the outer pulp of the Saguaro can expand like an accordion, increasing the diameter of the stem and, in this way, can increase its weight by up to a ton.

Saguaros are slow growing, taking up to 75 years to develop a side shoot. Some specimens may live for more than 200 years; the champion saguaro grows in Maricopa County, Arizona and is 13.8 m tall and has a girth of 3.1 m - it was injured as a result of the Cave Creek Complex fire which was started by lightning June 21, 2005. In addition to being slow growing, they are slow at propagating. These two factors argue for the placement of the saguaro on the endangered species list. Harming one in any manner (including cactus plugging) is illegal by state law in Arizona, and when houses or highways are built, special permits must be obtained to move or destroy any saguaro affected.

The Saguaro has a surprisingly shallow root system , considering its great height and weight. It is supported by a tap root that is only a pad about 3 feet long, as well as numerous stout roots no deeper than a foot, emanating radically from its base. More smaller roots run around to a distance equal to the height of the Saguaro. These roots wrap about rocks providing efficient anchorage from winds across the rocky bajadas.

The night-blooming flowers appear April-May and the juicy red fruit matures by late June. Saguaro flowers are self incompatible and require a pollenizer to supply viable pollen. A well-pollinated fruit will contain several thousand tiny seeds, and large quantities of pollen are required for pollination. The major pollinators are nectar feeding bats on the night blooming flowers, but they often remain open in the morning and some pollination may be accomplished by birds and insects.

Info from http://en.wikipedia.org/wiki/Saguaro

 Other basic cactus care questions

How do I know if a cactus is sunburned?

When is the best time to repot cacti?

Cactus Resources

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last modified-8/3/07

More questions? Email to email@alexandgregory.com

ABOUT THIS SITE: This site is a compilation of various cactus-related articles from the Web as well as our friends advice on growing cacti. The material is re-organized and might be changed from the original article. If you think your article or information is being used in improper way or you would like to enforce your copy rights please let us know, so we can update this site. Please note we don't make money off this site!