Living Rocks of Mexico
Slow Growing Cacti From Seed
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This article is reproduced form BCSS Journal Vol 15(1)1997, p16-20,. with the  kind permission of the Editor and David Quail.

David E. Quail


Old Oak Farm, Moor Edge Low Side, Harden, Bingley, West Yorkshire. BD16 1LD.

Photos by the Author

Raising cacti and succulents from seed has always been my special interest, which has resulted in the majority of my collection originating from this source. As I also tend to keep two or three of the best plants from each sowing, I have an abundant supply of good quality seed from the plants when they reach flowering size. This has encouraged experimentation with seed raising methods, as I can make proper comparisons from the different methods in the knowledge that they are based on the same seeds. Also, I can always be sure about the origin, age and quality of the seeds.

The method which has proved most successful for the slower growing cacti was discovered largely by chance. Having previously used a propagator (home made) in the greenhouse with average but variable results, I was looking for a more controllable source of heat and light, and, being a Yorkshireman, a method of heating which contributed less generously to the coffers of Yorkshire Electricity PLC. We are fortunate in having in our house a large airing cupboard with a hot water cylinder. The top of this cupboard was relatively unused and, after a period of delicate negotiations with my wife, I took possession of the top twelve inches, and installed a shelf, six feet long and fourteen inches wide Two five foot fluorescent lights were fixed to the ceiling, so that the bottoms of the tubes would be about six inches from the soil surface.

Initially, I used Grolux tubes but as these were expensive, I experimented with ordinary warm white tubes which gave identical results and I now use only the ordinary tubes However I believe that a tube which simulates more exactly the typical habitat light conditions may be better. The lights are controlled by a time switch which is set to provide fourteen hours of light per day. No additional heating was installed. The night-time temperature is usually in the 65 to 70°F range. During the day, with the extra heat from the lights, it is usually in the 75 to 80°F range, and occasionally slightly higher. The temperature variation between night and day seems to be beneficial and to some extent simulates habitat conditions Extremes of temperature are avoided, which previously caused problems. Very high temperatures used to occasionally inhibit germination, or damage the plants and particularly the fine roots, and caused the soil surface to cake. Too low temperatures caused rotting, infections and checks to the plant which retarded growth, sometimes permanently. With the slower growing cacti, these problems were often terminal, and the aim is to give them as near ideal conditions as possible and grow them fast (comparatively!), as they are only difficult when very small. Once grown quickly with no checks to their growth, they continue to develop much more quickly and become better looking and more floriferous than less favorably treated plants.

The growing medium used is John Innes number 2 potting compost (40%), washed river sand (20%), fine granite chippings (20%) and Perlite (20%), and any lumps which would inhibit the often delicate root hairs are removed or crushed. Half trays are used, as I sow quite a lot of seed, though occasionally I use smaller pots for individual sowings. The trays or pots are filled right to the top with the mixture, which is gently pressed down all over to ensure that it does not sink when watered. At this stage separators are inserted if more than one batch of seeds is to be sown in the tray. Then the trays are thoroughly soaked by standing them in warm water to which a suitable fungicide has been added. I use Murphy's Copper fungicide, though care is needed as exceeding the stated concentration or repeated applications have an inhibiting effect on germination.

Next the seeds are sown. I almost always sow seeds individually, which is not as much of a job as it may seem, and gives the advantage of saving time later in pricking out and avoids root disturbance and damage. Sowing is normally carried out in the depths of winter, when time is available. I tip the seeds into a small container such as a small lid, and use a tiny watchmaker's screwdriver. As the soil surface is now wet, since the trays are still standing in water, I simply touch the soil surface with the screwdriver, then touch the seed with the tip of the screwdriver. The seed sticks to the screwdriver where it is wet, and I then press the seed into the soil with the the screwdriver. For all but the smallest seeds, I also just cover it with a little of the compost. As this is wet, the whole operation is quite fast, and about twenty seeds can be sown per minute with practice. The spacing depends on how fast the seeds are likely to grow, but is typically about 3 or 4 per inch in each direction. As germination is normally at least 50%, and can be close to 100%, the space requirements of individual sowing are not excessive. Seeds are sown early partly because there is little else happening at this time, partly to give the seedlings as long a first season as possible, but primarily because my method does not depend on the vagaries of the English weather, and provides full control of the growing environment

When planning which seeds to sow in which tray, speed of growth and subsequent requirements need to be considered. My earliest efforts ignored this, and Aztekium was sown next to Trichocereus with inevitable results. The very slowest growing cacti may stay in their trays for two or more seasons, so it is important that they are not overwhelmed by faster growing plants, or that unnecessary disturbance results from taking out the larger ones.

After a half tray has been filled, it is taken out of its water tray, and then completely enclosed in polythene, with some support for the polythene so that it does not subsequently collapse onto the soil surface when covered in condensation. My own method is to put two half trays inside a full tray, put wire hoops at each end, stretch the polythene over the top and tuck it underneath on all sides. For smaller pots, individual polythene bags can be used, with labels as supports, and the bags sealed. I try to ensure that moisture cannot escape from the polythene coverings, so that the soil stays consistently moist and almost never needs watering. In fact if I am busy, I can completely forget about the seeds for weeks.

These conditions are particularly successful for the choicer cacti, such as Aztekium, Ariocarpus, Strombocactus, Pelecyphora, Encephalocarpus, Turbinicarpus, Epithelantha and Blossfeldia. However I also use the same conditions for sowing most other cacti Some etiolate, particularly Lobivia and Sulcorebutia, so these are sown together and are removed to a windowsill once etiolation becomes evident In some cases, seeds do not germinate very well, but when moved later to natural light, further germination occurs. I have unfortunately not documented the genera or species concerned Some larger growing cacti, or those which come from cooler habitats, such as Trichocereus, Opuntia, Maihuenia and Austrocactus, are usually germinated on a sunny windowsill in the house from late February with good success Succulents generally do not do well in the airing cupboard, and so they too get the windowsill treatment. However, they all have the same compost, sowing technique, watering and polythene bags Some succulents need special treatment. Terry Smale's excellent article in Vol 5(2), pp. 39-40 (June 1987) of the Journal gave the ideal conditions for success with Conophytum seeds.

The faster growing cacti stay in the airing cupboard for between three and six months depending on space availability The slower growing ones stay for at least six months, and sometimes all season. These never etiolate, and grow into perfectly proportioned plants, especially Aztekium and Ariocarpus. Occasionally moss causes a problem, and wherever possible I sprinkle granite chippings on the soil surface once most of the germination is complete, when the plants are big enough and so do not get buried. Usually this is just before the moss becomes too troublesome, and suppresses it completely. For Aztekium and Blossfeldia, this is not possible, and I just use my small screwdriver to dig out or squash each strand of moss, which is laborious but reasonably effective. For next year, I shall experiment with coir compost to see if that inhibits the growth of moss.

It is important that we protect habitat plants by perfecting methods of propagating the choicer plants successfully and satisfying collectors demands from these sources. I hope that this article has provided some ideas which members may wish to try out in whole or part. However I take no responsibility for any marital disharmony resulting from the wholesale requisitioning of airing cupboards! I would welcome any further ideas and tips from readers.

Illustrations: (Will open in a new window)

  • Fig 1: Aztekium ritteri, 15 years old

  • Fig 2: Aztekium ritteri, in original seed tray, 1995 sowing, 18 months old

  • Fig. 3: Ariocarpus trigonus, 14 years old

  • Fig. 4: Ariocarpus furfuraceus, 8 years old

  • Fig. 5: Ariocarpus furfuraceus, 8 years old

  • Fig. 6: Ariocarpus scaphirostris, 11 years old

  • Fig. 7: Astrophytum asterias hybrids, 1995 sowing, 19 months old

  • Fig. 8: Astrophytum asterias hybrids, 1996 sowing, 7 months old

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