Cactusworld (BCSS) Volume 26, No. 1 March 2008
My very first frailea was a Frailea castanea Backeberg. I bought it because I was advised that it was a choice cactus, it would not get very big and was easy to grow. It seemed so small to me that naturally I thought it was a seedling. I put it in my little greenhouse (six feet square at the time) and watered it like all my other cacti. Yet it made no progress, neither would it flower, and I was very disappointed. Then a flower bud developed and I thought to myself "Hurray, it is going to flower", but still nothing happened. It had been in my collection for all of two years and it was still unchanged in size, making no progress.
As always happens with small greenhouses, it was not long before I ran out of space, and, alas, I consigned the little frailea to the waste bin, because I thought it should have been dead by then. Of course now I know that the plant was practically adult size and that it is usual for the flower buds not to open because fraileas are cleistogamous (producing seeds without opening the petals), and moreover the growing conditions that I had provided for the plants were not quite right.
A few years later I built a bigger greenhouse (10x8ft) and after seeing the frailea collection of a friend, where most of them were in 9cm (3 1/2 inch) pots, growing beautifully and flowering, 1 decided to give fraileas another go, this time with the seeds from my friend's plants. The seeds germinated well and I soon had several little plants. Since then my collection has increased with plants which I bought at nurseries, or more often from sowing seeds that I received from friends and from my own plants.
The secret for keeping fraileas happy and growing is to pot them in a soil with good drainage and aeration, and to give them lots of water. Fraileas do like more water than most other cacti. I have also found that by slightly over-potting them they grow much better and seem healthier, as they can be quite short-lived if not given correct growing conditions.
Most of my bigger fraileas are now in 7cm (23/4 inch) pots, and are placed in the greenhouse during the winter. In our recent warmer winters here in England, I also tried to keep them in an open, transparent tent and they love it, and even light frosts have not harmed them. My guess is that the air in the greenhouse can get too dry, while in the tent the winter humidity stops the plants from shrivelling up too much. The fraileas that remain in the greenhouse do get the occasional light spray of water during the winter.
In the summer most of the my fraileas are outside, receiving morning sun and afternoon shade. I place their pots in trays with no holes, because if there has been a long dry spell, they like the tray to be filled with rainwater (or tap water), which soon disappears, quickly absorbed by the plants, and one can almost see the little bodies swelling up. After a day or two, it is best to drain off any remaining water in the tray.
Providing fraileas with lots of water is the key to growing these plants well. Watering from below is a good way of supplying moisture and humidity for these plants, since it is drawn up slowly into the soil. This is even more important for fraileas kept in the greenhouse, since the higher temperatures in the greenhouse can make the soil dry out very quickly. I fill the trays about half full. It works best in my conditions if I do this about every three weeks in the summer and if possible with rainwater, which is always better to use than tap water. I find that within a couple of days after watering, the plants will flower, sometimes with 4 or 5 of the relatively big yellow flowers at once. Even when their flowers do not open, they still form fruits with many seeds, that I usually sow in order to propagate my plants.
The compost used for sowing is the same that I use for all my seeds: 50% John Innes No.2, 25% horticultural grit and 25% Ultrasorb (which looks like small red clay granules). I fill the seed trays and stand them in a tray of water, until all the soil is wet through. Then I sow the frailea seeds fairly thinly on the top, so that they can grow to a reasonable size before they have to be pricked out into a bigger tray. The seed trays go into a heated propagator on a windowsill where they catch the afternoon sun. It does not take long for the seeds to germinate, and some will do so within a day or two after sowing. When they have reached a height of about 1 cm they are pricked out into a larger tray, where they remain until they are large enough to go into individual pots.
I try to have at least two plants of each frailea species. I have a few more still of my favourites, particularly Frailea mammifera Buining & Brederoo ssp. mammifera (yellow spines), F. mammifera ssp. angelesiae Kiesling & Metzing (brown spines) and F. castanea.
In my opinion fraileas are very easy to grow, do not take up much space and have impressive flowers, as long as they are not allowed to remain too dry.