This article is reproduced form NCSS Journal Vol 36(1)1981, p22-23, with the kind permission of the Editor and David Rushforth
Editors Note: The original black and white illustrations which accompanied this article have, with the authors permission, been replaced with new more relevant color photographs.
Since the publication of my letter in the June 1980 issue of the Journal I have had a seemingly endless stream of correspondence with growers anxious to speed up the growth of certain seedlings, and to propagate as quickly as possible rare plant material, by means of Pereskiopsis grafts. Although details of the use of Pereskiopsis for grafting seedlings have been given before, I have come to the conclusion that a reiteration of the technique is desirable - my technique, that is, as there are several growers in this country who use the stock and their methods may differ from mine.
It is no good treating Pereskiopsis like Ariocarpus. They need very generous treatment with good soil, plenty of water and feed, and warmth. Some years ago I planted a cutting in a six-inch pot in April and gave it 'the works'-in six months it was eight feet tall with many side branches and very long black spines. I have not done this since! A minimum temperature of 10oC is desirable in winter, but a little lower will do no harm for short spells, and some water during the winter helps the plant to start into active growth in the spring. If they get too dry all the leaves fall off, and it takes a few weeks to get the plant growing well enough to do anything with. As with any other grafting stock, it is vitally important that it is in vigorous growth before any attempt is made to graft on to it.
The grafting year begins in January, more or less coinciding with the start of the seed-sowing season. At this time cuttings about 10 cm. long are taken from stock plants (normally plants that have been used for grafting and have failed and subsequently sprouted, not plants that are years old and struggling to survive). These are potted, without drying, into 5-6.5cm pots of good compost. They then go into the propagator, where they are kept at about 15oC and well watered. After a week or two they are well rooted and begin to grow. By the end of March they are ideal for grafting on; in full leaf, vigorous and very juicy. Also, at about 15cm long they are of a manageable size. This size is not critical, as some seemed to think. You can use any size you wish but when you get, after about two years, a 7-10cm diameter scion on top of a 30cm stock, things begin to sway. Have you ever tried to remove ten million Pereskiopsis spines from your hand?
If you have concentrated thus far you will no doubt have realized that the seedlings planted in January, just before you took the cuttings, are now sitting there just waiting for the treatment. Indeed, I find that late March and early April is an ideal time to graft seedlings, as it allows ample time to regraft the top and sometimes the resultant offsets during the same season. Of course, you don't have to regraft, and can expect continued growth of the scion for several years, although the rate of growth progressively declines as the demands of the scion increase. I have kept plants on Pereskiopsis for over eight years but would not recommend this, better results being obtained by regrafting onto Trichocereus.
Two things are desirable for performing the operation, a steady hand and reasonable eyesight, otherwise you might end up with Pereskiopsis 'digitiformis' and a wart on the end of your finger! Also useful is a clean, preferably new, razor blade. If you can get them with three holes instead of a slot, so much the better. I tend to graft in small batches; say six at lunchtime then six more in the evening, as otherwise they get in the way, and each time use a new blade (they are quite cheap and can subsequently be used for other purposes).
Having selected the seedling you propose to graft, prepare the stock by cutting off the top half inch. The stock should be bright green and sappy, and very easy to cut. This piece can be set aside for rooting for future use. It is then wise to cut a thin sliver from the stock, leaving this in position, to keep the cut portion clean and moist. Cleanliness is very important as any infection in the wound is death to the union. Removing the seedling from the seed pan presents no problems to a grower with a steady hand, a good eye and plenty of confidence-simply pick it up with a pair of tweezers and deposit it between finger and thumb of the other hand. It is now necessary to remove the base of the seedling. Provided that you make this cut with the root end between your fingers, the top of the seedling will adhere to the razorblade. By addressing the blade to the stock the sliver can be removed and the seedling slid across very quickly indeed. It is of course essential that the two cut portions are in contact, and a lens may be necessary to check this, especially if you are grafting something like Blossleldia or Strombocactus. Incidentally, with these very small seedlings try to leave a tiny bit of the seed pan soil adhering to the base before you cut, otherwise it is extremely difficult to decide which way up they go.
I try to leave the whole lot undisturbed for a few hours, after which they are transferred to the propagator and grown on as normal, but if it is very hot and sunny they will need some shade until they start growing, otherwise the tiny scion will dry up. You will notice that I have made no mention of using weights. I have found that I get better results with small seedlings without any weights at all, although if the seedling is over about an eighth of an inch in diameter I use strips of glass about three inches by a half inch, balanced on pots of an appropriate height, varying the position of the fulcrum with the size of the scion. It is very important to put a label in each pot, as in two or three days you will not remember what you have done.
You will find that, after practice, you will get over 90% success. Those that do not take will throw out roots and can be returned to the seed tray. After that it is up to you. Either leave it to grow, or behead it after a few months and regraft, leaving some of the scion behind to develop more heads. It is always surprising to see the number of cristates that form in this way.
Several correspondents have asked me if seed of Pereskiopsis is available. As far as I am aware it is not, but having acquired your cuttings of this plant it is very easy to ensure a good supply for all your needs simply by rooting down the shoots that form. If you cut off the growing point of a stem, usually four or five shoots will form, and in no time at all you can have quite a bush. I can normally start people off with an initial supply.
Whether or not this appeals to you, It is a fascinating way of propagating plants and, over the years, has given me endless fun, many rare plants and of course many friends.
Illustrations: (Will open in a new window)
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