jp29 wrote: ↑Sat Aug 02, 2014 10:03 pm
I grew a great many Melocactus a number of years ago and had a collection consisting of mature plants of just about every species available at that time that I grew from seed -- or that Dan Bach gave me. Here is a pic of part of that collection (with a couple of
Discocactus thrown in):
Caveat: I dug that pic out of an archived folder on my PC. The quality (resolution) isn't very good because it was taken before the advent of widely available digital cameras. That holds true for many of the
Melocactus pics I will be posting to this thread.
I think
Melocactus have a tarnished reputation (a "bad rap") with most cactus enthusiasts (especially beginners) as being very touchy and difficult to grow. Well they certainly have different needs and require a somewhat different growing environment than most other cacti, but they are very rewarding plants if those needs are met. These are warmth loving cacti - they only grow naturally in tropical regions, in many cases in close proximity to the ocean. In cultivation they mostly do not tolerate well cold greenhouses or cold drafty windowsills - they mostly prefer a bottom winter temperature no lower than about 40 degrees F.
Seedling and small
Melocactus grow very well as indoor windowsill plants where they flourish in the winter warmth. They do not need any winter rest. Small growing species such as
Melocactus matanzanus can be grown to maturity on windowsills (and staged outside during warm weather) where they make striking specimens with their bizarre and colorful cephaliums that produce rossettes of pretty flowers followed by crops of pink, red or white fruit.
I think
Melocactus have kind of been cloaked in mystery and shrouded in myths for many cactus enthusiasts for a long time. I would like to give you all my take on some of those myths:
1. "Cultivating
Melocactus is very difficult and should only be undertaken by skilled and experienced growers" Not true. If their needs are met they can be easily grown and maintained by beginning growers.
2. "
Melocactus have very widespread and shallow root systems and should only be cultivated in wide and shallow containers". Not true. Healthy, robust and perfecty formed plants can be grown and maintained in regular containers as can be seen in the pics accompanying this thread.
3. "They must be grown in porous clay pots to insure proper root aeration". Not true. They grow very well in plastic or glazed pots. In fact, porous clay pots are a detriment -- the watering solution evaporates through the porous sides robbing the plant of nutrients and eventually leads to unsightly containers.
4. "They are very difficult to re-pot and their root systems should not be disturbed". Not true. How do you think all of the large, mature, specimens I depict in this thread ended up in those big containers? Do you think I planted them there when they were little seedlings? Obviously not. They were all "up-potted" as they grew -- many of them several times even after developing cephaliums, All that is required is that the re-potting be carried out in warm weather (I prefer early summer) and that they be placed in a warm location after re-potting.
Root system of
Melocactus zehntneri:
BTW, I personally break up the root ball gently and slightly on my own plants, trimming off any straggly or broken roots. I then let the roots dry off well and then pot the plants in my barely moist (and fresh) growing medium in order to better and quicker re-establish them . I do not wash off or treat the root system prior to potting. I have never lost a
Melocactus using this methodology. Having said that, you should wash and treat the root system of plants you buy or receive from others or if you suspect any root mealy bug infestation etc. before re-potting.
EDIT: Revised Cultivational Information:
Much of my cultivational methodology is based on that espoused by Dr. Franz Buxbaum in his book CACTUS CULTURE BASED ON BIOLOGY (translated by Vera Higgins), Blandford Press, 1958. He was the father of using coarse inorganic growing media for superior root aeration; acidifying water & soil by testing and modifying the pH; and using non-porous pots.
I use a General Hydroponics GH1514 Ph Control Kit to test and modify pH.
CONTAINERS: I mostly use plastic pots with generous drainage holes.
SOILLESS GROWING MEDIA: I have always used very open and porous media in order to insure superior drainage and root aeration.
I presently use an inorganic medium that consists of just one component -- what I call "freshly mined and raw" pumice - unscreened with all the fines present - it tests at neutral pH 7.4.
Raw, unscreened and unsifted/unwashed, pumice as described above
I don't screen out the very small granular pumice fines - but I do wash out the dust using a fine sieve in conjunction with a "power spray head" garden hose as dust tends to migrate to the bottom of containers where it can form a drainage impeding "sludge".
Washing out dust using a "power spray head" garden hose and fine sieve
Washing continues until the water from the sieve is reasonably clear
The pumice described above after washing it to remove dust
I perform a final rinse wash using my acidified city tap water.
Discocactus grown in pumice prpared as described above
I do not use any gravel or crushed rock top dressings for my containers as I have found that they impede the natural surface evaporation I desire.
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A mix that I have frequently used with excellent results consists of 80% pumice prepared as described above and 20% aged and weathered pine bark screened to remove large particles.
Unlike the Inorganic growing medium described above, these two mixes contain organic components that will require different fertilizing regimens from that described below.
You could just as well use an open and porous "gritty organic mix" (maybe with fired calcined clay such as Turface or a similar product) that provides good aeration and drains well.
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WATERING: I insure my plants receive copious amounts of water during the hot Arizona summer months. When I water during this time I do it from above and soak the plants until water runs freely from the drainage holes. I use a watering can with Tucson City tap water which is somewhat alkaline (variable pH 8.0 to 8.2 according to the City Water Department). Habitat information suggests that these cacti grow in a somewhat acidic environment and so I adjust the city tap water so that my growing media/water/nutrient solution mix tests at pH 5.5 to 6.0. During our Arizona summer "Monsoon" thunderstorm season normal rainfall (quite acidic in the pH 5.0 to 5.5 range) satisfies the needs of my container grown plants. I use my "adjusted city water mix" for any augmentation watering.
During very hot weather here in Tucson -- 100°F+ days with 75°F+ nights, which equates to roughly late May until mid September -- I sometimes have to water my small container grown cacti just about every other day (except, of course. for "monsoon" thunderstorm days). Actually, because these cacti are CAM plants (stomata opening at night during very hot weather) I water at early evening during this time.
FERTILIZING: In general I feed my plants with each watering during the growing season (spring through autumn) using liquid NPK 5-7-5 fertilizer (containing Magnesium and Micro-Nutrients) in conjunction with my pH adjusted city water.
SUMMARY: I am actually growing these cacti "semi-hydroponically" in that I don't re-cycle or re-use my watering solution
While the approaches, techniques and methodologies I outline above have worked well for me, they may not work well for others who I am sure will find ways of cultivating these plants better suited to their own growing environment and methodologies.
Edit -See my signature block for my updated cultivation methodology
There will be many captioned
Melocactus photos to follow.