Henry Shaw
Cactus Society
A CSSA Chapter
St. Louis, Missouri
www.hscactus.org
info@hscactus.org

[ CONTACTS ]

Henry Shaw Cactus Society members have collectively accumulated many years of experience in selecting and raising cacti and succulents. Some of their knowledge is reflected in the Plant of the Month pages, which provide background and growing tips for various species. Members also welcome inquiries and provide responses based on their experience and other HSCS resources.

Click the link below for a very general overview of cacti and succulents. With the huge variety of succulent species, forms and habitats in the world, however, be aware that not all points expressed here apply to every plant. For more information, call or e-mail the HSCS club contacts, or contact the Plant Doctor (plantinformation@mobot.org) at the Kemper Center for Home Gardening at Missouri Botanical Garden.

Additional questions and corresponding answers from HSCS members are posted below the link. To ask cacti and succulent questions, contact Mike Hellmann -- hscsdir1@hscactus.org, 618-656-1803. He will forward the questions as needed to appropriate members of the club for their responses.

General Cultivation Information
(Cacti and Succulents as House Plants)

Topics:
1. Introduction
2. Light
3. Temperature and Humidity
4. Watering
5. Soil
6. Fertilization
7. Repotting and Propagation
8. Cacti and Succulents That Flower
9. Common Cacti and Succulents

Cactus Questions

Q: "How long can I keep my cacti outdoors in the fall without fear of losing them?"

A: That depends entirely on the weather. Don't be too hasty -- let your plants stay outdoors as long as the overnight temperatures do not drop below 40 degrees. Take the more tender ones, including rhipsalis, epiphyllums and their allies, in around October. Many Southwestern cacti, such as echinocereus, ferocacti, opuntias and even mammilarias, enjoy the cool nights and often harden their stems to better withstand the dormant season.

Start diminishing the water supply, and in case of heavy rainfall, cover plants with plastic. If plants are kept in a greenhouse, don't turn on the heat except on frosty nights.

Q: "How should I approach watering in the dormant season?"

A: Watering is one of the most perplexing issues facing cactus growers. Appropriate watering depends largely on plants' location. If they are kept in a greenhouse, cacti do not need as much water as in a home, especially if the greenhouse is kept cool during the winter months. Syringing on sunny days will suffice.

Cacti kept in a warm home often do not receive enough light, and the air is excessively dry. Even if you withhold water, the plants keep growing, often becoming etoliated in the process. Therefore, keep the soil a little moist, but be cautious. Regular cursory examinations can help you master the watering situation.

Q: "Do cacti carry any type of poison or fungus on the tips? As with anything, I understand there may be germs."

A: As far as we know, there are no poisonous cacti, but some species with barbed spines can make you wish you were just dealing with poison. The toxic sap of euphorbias (milkweed) and other succulents can be irritating and cause rashes and even blindness in allergic individuals. And as you mentioned, bacterial and fungal pathogens on plants can cause discomfort as well as severe infection if spine fragments puncture the skin.

Q: "I understand air circulation is an important factor in raising healthy cacti. How much circulation is really needed?"

A: For smaller areas or rooms, an inexpensive, table-top fan will work fine. For larger areas, try a box fan. Again, inexpensive models usually do the trick. Some members run fans 24/7, while others use a more varied schedule. The important thing is to make sure your fan mixes the air vertically, to avoid defined layers of differing air temperature.

Succulent Questions

Q: "Since I've taken my plants indoors for the winter, I'm noticing scales and mealy bugs on them. What can I do?"

A: Before you bring plants indoors, clean them with a forceful spray of water to remove any dirt that may have accumulated, particularly among the spines. It may also be wise to use a spray to kill off tiny insects that may be attached to the plants' epidermis.

Mealy bugs are easy to recognize because they look like white fluffs of cotton. These insects often get on the undersides of leaves or where leaves and stems join. They suck plant juices and also secrete a sticky substance that often attracts a black fungus.

If the infestation is not great, pick off the mealy bugs with tweezers or knock them off with a forceful jet of water. Or apply alcohol with a swab to each bug or colony, but don't get any alcohol on the plants. For major problems, commercial sprays can cover infested areas more thoroughly and not miss insects in hiding.

Scales are small, flat or hemispheric, round or oval-shaped insects that are hard to remove because they cling tightly to plant surfaces. Commercial sprays are ideal to control these pests.

Q: "I have a Euphorbia that is reaching the ceiling of my office. Can I cut it back without putting the plant into shock or killing it?"

A: It's nice to have a "good" growing problem (too much height). Yes, you can prune the plant without putting it into shock. There are a couple of things to watch out for, though. When pruning, the white "blood" that comes out is toxic and can cause strong reactions. Wear rubber gloves and don't touch your face or other sensitive areas during the pruning event.

The best time to trim is spring or fall. Trim the plant with a clean knife cut. To help heal the cut and prevent disease, apply powdered sulfur from your local yard care store on the cut with a paintbrush.

To sprout the cutting, coat the "wound" with sulfur and set aside. After two weeks, pot in coarse soil and add a tablespoon of water every other week for two months. When overnight temperatures stay above 50°, place the potted cutting in a shady place and treat normally.