Rene's Urban Canadian Cacti





Cultivation Tips


Choice Of Species

There are approximately 3000 species of cacti. With so many to choose from, it is important to become familiar with lighting & space requirements as well as  growth & physical characteristics of this diverse group which includes columnar, barrel, globular and tree or shrub like species to name a few. Keep in mind space requirements as many species such as Opuntia quickly outgrow their environment and require regular cutting / pruning. They also have particularly annoying barbed spines that are numerous and difficult to remove. Safety can be an issue here!

I would suggest the smaller globular species such as discocactus, melocactus, astrophytum, gymnocalycium etc.,or one of the other smaller species such as mammillaria, rebutia, parodia etc. A large number of plants can easily fit on a sunny window ledge. Large columnar plants require a lot of floorspace, and while impressive they are difficult to transport without damaging them. Requiring at least two people, blankets, cardboard, gloves etc. My friend and I once had to transport six 10 foot tall Euphoria's (each with many arms and poisonous latex sap in large pots). Not a lot of fun. Personally I'd rather carry a 150 lb. barrel cactus any day.

Globular species are compact.

Columnar species are not.

Buy your plants from a respectable supplier. If you are buying from a local greenhouse, make sure to inspect it thoroughly for signs of pests.

When ordering from nurseries outside your own country be aware of the need for phytosanitary certificates and CITES certificates. Do not purchase plants have been harvested in the wild. Buy only greenhouse grown plants. This helps stop illegal harvesting of endangered species. Always enquire when ordering about additional costs and time requirements.



Choice Of Pots

I would recommend plastic for many species for water retention, weight savings, and cost. Clay pots are aesthetically pleasing and also dry out faster than a plastic pot, so where over-watering could be an issue; a clay pot may be the answer. Some species like Melocactus should be in plastic pots, or glazed pots as they prefer to be a little on the moist side, and the roots should not be allowed to completely dry out. For globular species try to keep the pot size 1 to 2 inches greater in diameter than the plant. Shallow pots are fine for most globular species as they don't require as much root space as columnar species. Columnar plants require a pot with a diameter that is one-third to one-half the height of the plant. Whether an indoor or outdoor pot it must have drainage holes. Place a piece of broken clay pot over the drainage holes to prevent the soil from being washed away. In very large pots you may want to put coarse gravel or clay pot fragments in the bottom to aid in drainage. Trays are handy items indoors, but remember to use plastic trays on carpet as clay trays will stain carpet, wood, and cushion floors.



 Variables taken into consideration

1) Type of Pot: Cacti in clay pots require more watering than do those in plastic.                      

2) Pot Size Generally the larger the pot the more infrequently it will require watering, and conversely the smaller the pot the more frequently it will require watering.          

3) Species also dictates water requirements. Some are very "thirsty", and others will not tolerate over watering.                                                                                                           

4) Light . The amount of light a cactus receives also dictates its water requirements. Plants in darker areas require less water.                      

5) Season. Do not over water in the winter or in a dormant period as it can lead to root rot and collapse of the plant. Watering in winter also leads to atypical growth patterns, due to reduced light levels. You can mist or spray your plants in the winter to avoid shriveling. As you get to know your plants and their water requirements you may develop a watering schedule, however it is always safer to err on the side of caution.                                                           

6) If in doubt don't water. Cacti can survive many months with no water, especially in winter

For the beginner I would recommend a moisture meter as it is difficult to gauge moisture content of soil by touch alone. 

I prefer to water most of my cacti from the top, that is to pour water right on top of them. I do not however pour huge amounts of water onto the cephalium of melocactus and discocactus as it tends to wash the cephalium away. I also avoid watering from above the fuzzy crown of echinocactus, and any "hairy" cacti such as oreocereus for the same reason. When watering, give enough so that the water runs freely from the drainage holes.

The most common indicator that you are over watering unfortunately is a sudden collapse of the plant commonly known as "black rot". Initially the roots rot from the bottom up, so the damage does not seem apparent until cooler weather arrives. If you see black, mushy areas of tissue usually around the base of the plant it is time for immediate action to save the plant as the infection can spread quite rapidly. All infected tissue must be removed using a sterile, sharp cutting tool. Make sure you cut into healthy tissue and ensure all diseased tissue is removed. The last cut into healthy tissue must be with a sterile blade. Apply rooting hormone to the exposed tissue, and allow to callous over. (treat as per cuttings.)



Pests & Diseases

The most common cacti pests include mealy bug, and scale bug.

The most effective organic treatments I've come across are the various insecticidal soaps such as Wilson's or Safers, or a "dormant" or "horticultural oil" in winter. Both treatments act as a surfactant and coat or smother the insect. It is important to follow the directions and re-apply the treatment in two weeks to ensure eradication of unhatched generations as the eggs are unaffected by the treatment.

 It doesn't hurt to apply it occasionally as prophylaxis. Extra dry conditions seem to permit mealy bug infestation, so a little extra watering might not hurt. Remember that healthy, well cared for plants with good air circulation are less likely to become infested.

When you bring a new plant home treat it as soon as possible. It is also a good idea to keep it separate from the rest of your collection for a few weeks to ensure all potential pests have been eradicated. Other pests I have encountered are ants, which on a couple of occasions attempted to colonize a plant which had been placed outside (ant traps did the trick there), and scale bug. For large adult scale bug you can wipe down the scale with isopropyl alcohol to break down the waxy covering and apply nicotine to kill the bug. You can use wet tobacco in a cloth for this. Adult scale bugs are not mobile, and once scraped off die. Repeat in a couple of weeks. Always inspect your new cacti closely before you purchase it. Look for any tufts of white "fluff" that may be an indication of mealy and for any small brown or grey/black "scales" around the base of the plant which are an indication of scale bug.


Artificial Lighting

Although natural sunlight is best, additional lighting may be needed. Fluorescent lighting is by far the most economical, efficient, and living space friendly. Fluorescent lighting provides three times the light of incandescent lighting. Four foot tubes seem to be the most readily available, and the most reasonable in price. Shop light type double tube fixtures can be found at your hardware stores at reasonable prices. These fixtures can be suspended from the ceiling or stood up in corners to provide side lighting. In areas where the view would be obstructed you can opt for incandescent spotlight type grow bulbs in overhead fixtures. Its a good idea to hook them up to a power bar and then to timers to avoid uneven growing cycles.

Leave the lights on 16 to18 hours a day in the summer and cut them back to 10 to12 hours in the winter to provide for a rest period.



Generally I only fertilize in the spring & summer during the growing period. If you fertilize continuously, atypical growth patterns may result, especially in the winter when light levels are low. Salts also may build up in the soil and stunt or kill the plant. You can use tomato fertilizer at half strength, but many brands of specialty cactus fertilizers are available. Cactus Juice is a good one. Some heavily spied cacti egg: Astrophytum Ornatum will benefit from crushed limestone added to the mix. Consult a good cactus encyclopedia for details regarding your particular species.



Growing from Seed

Seed is available commercially but for best results use fresh seed. In order to obtain fresh viable seed however you must first pollinate when your cacti are in flower. If you are lucky a bee will do it for you, however, a small artist paintbrush works just as well, transferring pollen from one plant to another. Once the plant sets seed collect the fruit or seedpod and wash the seeds to separate any organic material which may attract fungus. Wash all planting containers thourouly with soap and hot water. Use new cacti potting mix and microwave or bake the soil to sterilize it to prevent fungal or bacterial attack. You can use small pots and place them inside zip lock bags or I prefer clear plastic sandwich containers like those from the deli (with tops that snap shut) or shallow Tupperware containers. Sow the seed and cover them with fine grit and thoroughly wet the soil. Place the container in a warm 70 degrees+ shaded location. Strong seeds will germinate in a couple of days but it may take as much as two weeks or more.

When the seeds have germinated remove or open the cover every couple of days to provide air circulation and prevent fungal attack. If your seedlings do develop a fungal infection try a fungicide for damping off such as No-Damp. Mist your seedlings regularly and when they become large enough prick them out gently with tweezers and replant in nice even rows to prevent crowding. You may leave the seedlings in the propagator for almost as long as you want or until crowding becomes a problem. Beware you may end up with hundreds of seedlings but they make great gifts and get others interested in the hobby.

Taking Cuttings

Cacti can also be propagated from cuttings, and this is an excellent way to reproduce hybrids. When taking cuttings always try to obtain a decent size cutting as it will root faster and thus increase the chances of survival. Use a clean, sharp, cutting utensil to avoid chances of infection, and sprinkle rooting hormone to the freshly cut surface right away. Do not touch the exposed cut surfaces. Once the cutting has calloused rooting hormone is no longer effective. Allow the cutting to thoroughly dry and callous. Put the cutting in a dry shaded location. Depending on the species and the size of the cutting this may take up to a month. Be patient and do not plant until the cutting is well calloused over. Plant the cutting and withhold heavy watering for a couple of months. Many cuttings will enjoy regular misting and light watering to stimulate root growth.




Choice of soil for a given species is one of the most important choices you will make. Different species have differing water requirements, Ph levels etc., but remember to always use a well draining, porous soil. Many brands of commercially prepared cactus soil are available for the home gardener; you can shop around until you find one you like, or you can make your own.

I will often mix them together to achieve varying drainage and water retention characteristics. Various amounts of perilite, sand, loam, gravel and peat can be added to vary drainage characteristics of the soil. This can be especially important to plants that are prone to root rot.


Cold Hardiness

Different species have differing cold tolerances.  Most of my Desert Cacti have seen temperatures as low as -8 or -10 C, and some colder than that. Jungle Cacti, Melocactus, Discocactus etc will not tolerate much frost, so do your research. Astrophytum, Gymnocalycium, Ferocactus, Trichocereus, Echinocactus, Carnegia & especially Opuntia seem to be very hardy generally. There are a couple of Canadian Native Species that tolerate winter outside here in Nova Scotia just fine. Keep them dry and sheltered if possible, so as not to remain cold and wet for extended periods. A dehydrated plant will survive much lower temperatures, as it's natural "anti-freeze" is more concentrated.


Lophophora or 'Peyote'

Lophophora Williamsi

Lophophora are slow growing, spineless, psychoactive cacti with 52 alkaloids present.

Documented use of Peyote exists for at least 6,000 years. Considered a holy religious sacrament of the Native American Church, It has been used in religious ceremonies by Shamans for many thousands of years, by different cultures, throughout and beyond it's native range of Northern Mexico and Southern Texas.  Lophophora while plentiful in collections, are now endangered due to illegal harvesting and loss of habitat. Possession is illegal in USA for anyone not a member of the Native American Church. Numerous court battles are, and have been fought, over the issue of possession and its use in religious ceremony. 

LophophoraSeedlings  (left)    Melocactus (right)

Growing Lophophora from seed and on its own roots takes great patience. Often 5 years or more to get a flowering size plant. Grafting to a faster growing rootstock can greatly accelerate the process, reaching flower in 18 months.

 Grafted Lophophora

Natural Habitat Lophophora Sp.


Jungle Cacti

Mainly Epiphytic (tree dwelling) my experience with these cacti is somewhat limited.

 I do have a half-dozen plants or so. I enjoy them and place them in locations where desert cacti might not get enough light. These plants enjoy more frequent watering and misting than do desert cacti, and require plastic pots to maintain moisture levels, and to reduce weight for hanging purposes.

Let them completely dry out between watering, and use a well draining soil to avoid root rot.






Recommended Reading

The Complete Book of Cacti and Succulents-by Terry Hewitt-RD press. ISBN 0-88850-307-5 Hardcover, 176 pages. Excellent book with many nice pictures but no Discocactus section. Published 1993.

The Ultimate Book Of Cacti and Succulents-by Miles Anderson of Miles To Go cacti and succulent nursery in Tucson, Arizona.(Consultant Terry Hewitt)-Select Editions. ISBN 1-896639-36-4 Hardcover, 256 pages. Excellent book with many nice pictures but no melocactus section. Published 1998.

Pocket Encyclopedia Of Cacti in Color-by Edgar and Brian Lamb- Blandford Press. ISBN 0-7137-1197-3 Hardcover, pages. Many nice pictures but little info.

The World of Cactus and Succulents- Published by Ortho Books. ISBN 0-917102-59-2. Softcover, 96 pages. Interesting book with creative 1970's decorating ideas. Species names badly out of date. Published 1977


 The Cactus & Succulent Plant Mall - The Ultimate Links & Resource Page
 Gerard Ardisson - Cacti, Succulents, Caudiciforms, Peyolts and Cristations.
 Interactive Cacti Garden - I love this yard. Lots of Pictures.
 Blaise & Cloties Cactus Page - India - Excellent grafted Lophophora & Ariocarpus
Ariocarpus - Living Rocks Of Mexico
Genus Astrophytum - German/English Page - Heinz Hook
Cactus Webring Pages - A collection of cactus pages


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Last modified: April 22, 2007


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