You may want to be able to make a mass display, on a windowsill, or in an interesting pot or container. You may have plans for a carpet bedding scheme or some other big project which would be prohibitively expensive to develop if you had to buy each plant individually. You may have ideas of creating surplus plants to swap or give away. Or you may just enjoy “pottering” with your plants.
In fact, Glenhirst Cactus Nursery started from a windowsill collection in a Birmingham flat, after a visit to a National Cactus and Succulent Society Exhibition at the Botanical Gardens in the city. Once we got the hang of propagation, there was no stopping us, so you obviously have to be a bit careful that the enthusiasm for plant creation doesn’t get out of hand!
There are several techniques which can be used; these are treated in order of difficulty in the following pages, with advice on how to proceed based on our techniques here at the Nursery. Subsequent care and the developments which can be expected are also covered.
All you need is patience!
Many cacti will take matters into their own hands and produce their own miniature replicas of themselves with no help from you whatsoever. Many of the globular cacti, like Rebutias, Echinopsis, Chamaecereus, Lobivias and Mamillarias are freely offsetting plants. Therefore, you have a choice. Either you can allow your plant to grow into a large multi-headed clump, where each little plant will continue to develop alongside its parent. Or, alternatively, you can separate the little “pups” from their parent plants and pot them up separately.
You will find that you can often gently detach the plant, which will be a perfect miniature of its parent, including a root system. Occasionally, the offset has to be severed by using a sharp knife. In this case, allow the cut section to dry out for a few days before planting up the offset. Carefully separate the plantlet, and pot it up into any house plant compost. You can use John Innes soil-based compost, numbers 1 or 2, a peat-based compost, which will benefit from the addition of a little gravel, or any of the new, coir-based variants, again with the addition of a little gravel.
Sometimes there is a degree of flattening on the edges of your new plant, because it has grown in a compressed position between the plant and the edge of the pot. However, once separated it will grow quite happily and will soon take on its correct form.
Notocacti have an unusual variant in that they do offset readily, but they often produce underground offsets; explore the soil gently with your fingers to find them, and then you can treat them in the usual way.
Some succulents, like Agaves and Aloes, produce offsets on thickened runners which develop in the root system; these, too, can be gently separated from the parent plant and potted up directly as they already have their own root systems.
Clump-forming succulents, like Lithops and Conophytums, can be divided readily to produce more plants. Separate them gently and wait ten days or so before potting them up in your usual compost.
However, not all plants present you with such easy methods to increase their numbers. In many more cases, you will have to be more ruthless in order to increase your plant stocks. Your essential tools are a clean, sharp, unserrated knife and some clean, empty plant saucers or seedtrays to lay your plant material in while it dries out.
Taking stem cuttings is a form of vegetative propagation. The resulting plant will be identical to the parent plant, which can be vital if some feature of the parent cannot be perpetuated in any other way, e.g. variegation. Variegation in a plant is not perpetuated by leaf cuttings however; there has to be some stem involved, or you will find that the plant will revert to solid green again.
Cuttings should be severed at a natural joint if possible, at the side or base in the case of a branching cactus, or choose a stem or pad in a jointed species. Your cuttings are most easily rooted up during the growing season. Late spring and early summer are the best time for taking cuttings, and all propagation is best done between March and September.
Most cacti and many fleshy-stemmed succulents can be propagated by stem cuttings. This is also a good way to increase some of the exotic flowering cacti, like Epiphyllums, Aporocacti and Selenicereus, all of which root readily as stem cuttings; as the correct way up is often indistinguishable with these cuttings, ensure that you know which is the top and which is the bottom, and be sure to insert them in the rooting mix.
Take great care with Euphorbia cuttings, as these plants have a milky and irritant sap. In their case, begin taking your cuttings from the bottom of the plant and work your way upwards; this way the sap will not drip on you as you continue to take your cuttings.
Your cuttings can take the form of a beheaded stem or, in the case of Opuntias and some other branching subjects, you can choose to remove a pad or a side branch.
There are several pressing reasons for cuttings to be taken as well as simply increasing your stock of a plant.
A damaged plant can often be rescued if the healthy part of the plant is removed above the area of rot or damage and re-rooted. A columnar plant which is outgrowing its space can be beheaded and a new smaller plant established. The cut portion will also resprout with several heads which can in turn be removed and rooted.
Plants which seem to have become less vigorous – a fault with some Opuntias – will often make much faster growth when a pad is removed and rooted separately.
You also have the chance to tidy up a plant which has become too tall, top-heavy etc.
Decide beforehand where you want to make the cut in the parent plant, and try to make a smooth, even cut, with no rough edges. Put the cutting in a clean container and lay it in a dry, shady place – perhaps under the greenhouse staging – where it should remain to dry out for a week or so. A longer rather than shorter period is desirable, but it depends very much on the temperature. Higher temperatures mean that the cutting takes much less time to be ready for potting up, but if you are in any doubt, wait for rootlets to form, when you will be certain of success.
Unlike most other plants, cacti dislike wetness; they are the last plants to root up by standing them in a glass of water. They do not have the resistance to bacteria and fungus infections carried in moisture which plants originating in wetter areas possess, and they can succumb to rot disappointingly easily. Therefore keep them dry! As mentioned above, they will often surprise you by already producing tiny roots even before you come to pot them up.
After a week or two pot them up into slightly moist compost – any house-plant compost will do, peat-based with extra gravel or a soil based John Innes mixture. Water sparingly until they show signs of growth, when you can commence to water and feed as usual.
Many succulents, like Echeverias, Crassulas, Kalanchoes, Haworthias and Sedums for example, can be propagated quickly and easily by removing a leaf from the parent plant and allowing it to dry out as described above. Choose a plump healthy leaf, and you will find that a whole new miniature plant will develop from the base of the leaf, which will eventually shrivel away.
Rosette-forming succulents can be set with a small piece of stem still attached. Aeoniums can be propagated by taking one of the rosettes which form its crown.
Yuccas and Agaves both produce very thick branching amongst some of their roots, quite distinct from the thinner, more fibrous roots.
New plants can, with patience, be grown by cutting off pieces of engorged root and allowing them to dry out. In time, complete new plantlets will form from these pieces; sometimes more than one per section. The pieces should be at least 2″ long, and should preferably have some fine roots on them already.
After a plantlet develops its own roots, cut it off the parent root.
Many of your cacti will reward you with a show of flowers in the spring and early summer and these plants will then go on to set seed. Keep an eye on the ripening seedpods, for once they are dry they should be removed from the plant. The fresher the seed the better. Furthermore, seedpods left on over the winter can be a focus for rot and decay; they are also susceptible to raids by hungry mice!
Some pods can be split and the seed will cascade out ready for sowing. Rebutias will flower readily in the spring, you can collect the ripe seed and have it germinating by July!
Some of the seed pods are fleshy, like Mammillarias, for example. To remove this seed squash the pod, then soak it well, when the heavier seed will separate from the pulp, dropping to the base of the container while the debris floats above it. Lithops have apparently impenetrable seedpods; a drop of water on these and the pods peel open revealing a fine, dust-like seed.
If you want to be certain that seed is pure, you must protect the flowers from the attentions of pollinating insects, and take pollination into you own hands by using a new, clean paintbrush to cross-pollinate your chosen flowers.
You can also make deliberate hybrids, by selecting likely parents. Epiphyllum growers have produced a cornucopia of beautifully coloured hybrids by this method. There is also scope with some of the small, easily-flowered globular cacti, like Rebutias, Sulcorebutias and Chamaecereus.
To ensure that nothing interferes with your work, put a polythene bag over the chosen flower after pollination, and don’t forget to label it with the details of its “father”.
Grafting is a more complicated method of plant propagation, but it can be a useful technique for a variety of reasons.
Some cacti, especially the rare and choice varieties like Aztekium, Pelecyphora, Lophophora etc., are very slow growing and can take an excessively long time to reach maturity if grown on their own roots. In this case, grafting them as seedlings can accelerate their growth. The grafted plant is likely to become more engorged and often produces many offsets. It can be left indefinitely to grow as a composite grafted plant, or the plant can be taken off the stock plant and treated as a cutting when it has grown big enough. This is also a technique to rescue a damaged or diseased plant, which can often be saved by grafting a healthy portion of the plant onto a stock plant.
Grafting also allows the growing of forms not found in nature. For example, the Japanese have spent many years developing a range of Gymnocalyciums without chlorophyll, in shades of pinks, creams and maroons. These plants could not grow if they were not grafted on a green stock for chlorophyll production.
The unusual wavy and crested forms of cristate plants, which have developed as a result of damage to the growing point, fascinate many people and often grow better when grafted.
Some people also use this technique to create a “standard” Christmas cactus, in the way that gardeners produce standard roses.
The best time for grafting is when plants are in strong growth, and again the late spring and early summer is probably the most favoured time for trying this technique. Success rates are lower than in other methods of propagation, so it is probably wise to try to take several grafts at the same time in the hope that a proportion of them will be successful.
The scion is the cutting or seedling which is to be grafted, and the vigorous rooted host plant is called the stock. A cactus plant obtains food and nutrients through vascular tissue; this can be seen in cross section when a cactus stem is sliced through as a slightly darker core in the centre of the stem, surrounded by a circle of cells which act as water storing tissue. For a graft to be successful, the vascular tissue in both the stock and scion has to be in contact in at least one place, and the larger the areas in contact, the more successful the graft is likely to be.
The stock plant should be a sturdy, fast growing cactus, such as Trichocereus or Pereskia. A youngish plant, say a year or so old, is the best choice as this will be at its most vigorous, and the stock should be at least as wide or ideally a little bit wider than the scion.
In flat grafting both the stock and the scion should be cut straight across in a clean cut, with the edges of both pieces chamfered to fit together to avoid shrinkage. Look carefully at the stock and the scion for the vascular rings which should as far as possible be lined up, because this it where the plants will bond together. Try to avoid any air bubbles becoming trapped between the two cut sections by gently rotating the pieces before finally fixing them. The two pieces should be held together firmly either with crossed over elastic bands going over the top of the scion and down underneath the pot or string tied in the same position. Some people use cocktail sticks or long cactus spines to hold the union together.
In the case of long, slender scions, when a columnar cactus is being grafted, there is a variant where the stock and the scion are cut on the diagonal and married together.
Keep the pot in a bright position out of full sun for two or three weeks after which the graft should have taken and the bands can be removed. Protect from full sun until the scion shows obvious signs of growth when the plant can be treated just like any other member of your collection.
The other method is the use of a cleft graft; this is appropriate for Christmas Cacti and epiphyllums. In this case the stock has a V-shaped cut made into it, and the flat scion is tapered to shape and pushed down into the cleft to a depth of about 1″ (2.5cm); the stock and scion are held together with a long spine or a cocktail stick. Cleft grafts need a little longer to take than flat grafts, allow a week or so longer and give them a shadier position; the composite plant is then treated in the same way as in the flat graft method.
Do not water any of your grafted plants until you are certain that the graft has taken.
The techniques desry.cribed in this article have been tried and tested here at the Nursery, and we have found that they have high rates of success.
But one of the pleasures of working with living things is that they can always surprise us, so don’t be afraid to experiment!
Good luck and happy growing from all of us at Glenhirst Cactus Nurse