Organic Gardening Tips and Methods Propagation Methods and Tips Producing Hybrids; When growing Cacti and other Succulents in a mixed collection, cross- pollination may occur, ie; pollen from the flowers of one species or cultivar may pollinate those of another to produce a hybrid offspring, sometimes these hybrids are improvements on other types raised and may be worth propagating, more frequently, however, they are not worth keeping. To be sure of raising plants with the desired characteristics it is necessary to control the pollination process, controlled pollination may be used to produce further plants of the same species which retains the parental characteristics or purposely produce hybrid offspring from different species (which combine the characteristics of the parent plants), to produce a new hybrid, choose the parent plants (usually species of the same genus) in an attempt to combine the best characteristics (eg; leaf shape or flower colour) of both parents, to prevent open pollination by insects occurring, just before the stigma appears receptive or the anthers are ready to dehisce, tie a small paper bag loosely over the flowers that are to be used, transfer the pollen from the anthers of one parent plant to the stigma of the second parent plant by hand using a soft brush (such as a make-up brush), then re-cover the hand pollinated flower with a paper bag. Many Cacti and other Succulents are not self-fertile, and it is essential to cross pollinate in order to obtain seed, if a species is self fertile, however, cover the flowers with a bag (as above) to prevent cross pollination by insects, a gentle tap on the bag is usually sufficient to spread pollen onto the stigma’s within the flower and effect self pollination, as the fruits ripen, they become soft and fleshy and may release seed, if not, slice the fruits open and leave them for two or three days in a partially shaded but warm position so that the pulp dries out, then wash the seed to remove the pulp and dry it on blotting paper before sowing. Stem Cuttings and Stem Sections; Stem cuttings may be used to propagate many species of succulents including Euphorbia, Stapelia and most Columnar Cacti... Take stem cuttings or sections in early to mid-spring, the amount and type of stem material that is removed depends on the plant, some cacti such as Opuntia consist of a series of rounded pads or sections that may be severed with a sharp knife at the joint base for propagation, for plants that have flattened leaf-like stems, for example; Epiphyllum, make a cut across a stem to produce a section 15-22cm (6-9in) long, to avoid disfiguring the plants, remove a complete “leaf” at the point where it joins the main stem and treat this cutting or cut it into several sections, most columnar cacti and some Euphorbia species may have sections of stem removed to provide cuttings, all Euphorbia species and some Asclepiads produce a milky latex when cut, to stop the flow, dip the cutting into tepid water for a few seconds, seal the cut on the parent plant by holding a damp cloth against the wound. Avoid getting the sap on your skin because it can cause irritation, leave stem cuttings in a warm dry place for anything from two days to two months to allow a callus to form before potting them up in suitable compost. Inserting the Cuttings; Insert one stem cutting centrally into a prepared pot, or place several small ones around the edge of the container, the cuttings should be inserted just deep enough to stay upright but not too deeply, as otherwise the base of the cutting may rot before they have rooted, stem cuttings from succulent that bear true leave such as Pereskia, need to have the lower leaves removed before they are inserted in the same way as non-succulent plants, apply a mist spray of tepid water occasionally, but do not over water as this may cause the cuttings to rot. Rooting normally takes place after approximately two weeks, although cuttings from some genera such as Selenicereus may take a month or more. Division of Offsets A large number of clump cacti and other succulents such as Conophytum, Mammillaria and Sedum may be propagated from offsets early in the growing season. Clump-Forming Offsets; Scrape away the top layer of soil from around the parent plant to reveal the base of the offsets and carefully detach one or more from the parent plan as required with a sharp knife, treat any wounds on the offsets with a fungicide, leaving them to dry for two or three days to allow a callus to form, pot up undamaged offsets immediately. Rootless offsets should be inserted into compost made up of equal parts; fine peat substitute (or peat) and sand, if the offsets have already developed roots, use standard potting compost, use appropriately sized containers/pots with a layer of “crocks” at the bottom of the container/pot (to help drainage), pot-up offsets separately and water them lightly, keep the potted offsets in semi-shade for about two weeks at a minimum temperature of 15 degrees-C (59 degrees-F), and water them again after the first week, once the new growth appears, the plants should be potted on into a standard potting compost and the normal watering routine applied. Offset-Tubers; Some tuberous-rooted succulents, such as Ceropegia produce small offset tubers around the main tuber of the parent plant, these may be treated as divisions and grown on to produce new plants, during the dormant season, remove some of the compost to reveal some of the offsets and separate them from the parent plant using a clean sharp knife, treat the surfaces of the rootless offsets with fungicide and allow a callus to form, insert each offset tuber in a clean pot that contains a mix of equal parts, peat substitute (or peat) and coarse sand, if the offsets have roots, place them directly into a standard potting compost, top-dress with a thin layer of washed, sharp sand-grit and label, place the pots in semi-shade and maintain a temperature of 18 degrees-C (64 degrees-F), allow the tubers to settle for three or four days and then water them regularly with a fine mist-spray (taking care not to over-water), as soon as growth starts and some young shoots start to appear, follow the normal watering routine, pot-on into a standard potting compost as soon as the young plants have several shoots and have become well established. Division of Rootstock; Many species of Aizoaceae such as Delosperma and Frithia, some clump-forming cacti and genera such as Aloe are readily propagated by division, for some cultivars of Saservieria, division is the most reliable method of retaining the variegation, as leaf cutting may produce plants that revert, divide clump-forming cacti and other succulents in the early stages of the growing season, lift the whole plant from its pot and carefully pull apart or cut the rootstock into a number of smaller pieces, each with a healthy bud or shoot with well formed roots, treat all cut areas with fungicide and pot up each section separately into standard potting compost, label, water and place in a semi-shaded position until well established, alternatively, cut away a piece of the rootstock without lifting the plant, and ease section out of the soil with a hand-fork, dust the cut surfaces with fungicide and pot-up (as for tubers), fill any gaps that are left around the parent plant using a standard compost and water lightly. Grafting Some cacti and other succulents, notably certain members of the Asclepiadaceae, such as Edithcolea and Pseudolithos, are slow to mature and flower when grown on their own roots, by grafting them onto established specimens of related species that are quicker to mature, they can be induced to flower much faster, during the growing season the top growth or the scion of the required plant is grafted onto the rootstock of one of the more vigorous species, three grafting methods are/may be used, Apical-wedge grafting, Flat-grafting and Side-grafting. Apical-wedge Grafting; Epiphytic cacti are often propagated by apical-wedge grafting in order to create an erect “standard” or tree-like plant, use; Pereskiopsis or Selenicereus, which are sturdy but of slender growth (as the rootstock), to produce the rootstock, take a stem cutting of the selected plant, when this has rooted and shows evidence of new growth, it is ready to be used for grafting, slice off the tip and then make two standard downwards cuts into the top of the rootstock stem to produce a narrow, vertical “v”-shaped slit approximately 2cm (3/4in) long, select a healthy shoot from the scion plant and prepare it by trimming the lower end into a wedge-shape to match the cleft in the stock, insert the prepared scion “wedge” into the cleft so that the cut surfaces match as closely as possible, secure the stock and scion firmly in position either by pushing a cactus spine horizontally through the graft, or alternatively, by binding with raffia or a weak clothes-peg, place the grafted plant in partial-shade at a temperature of; 21 degrees-C (70 degrees-F), the stock and scion should unite within a few days, once this has happened, remove the spine or raffia (or clothes-peg), dusting any holes made by the spine with fungicide, when fresh growth appears, water and feed as for established plants. Flat-grafting; This method is used to propagate crested variants (succulents with a typical, often contorted growth), certain other succulents with tufts of hair, and Gymnocalycium mihanovichii and Echinopsis chamaecereus as their seedlings may be lacking in chlorophyll, genera that can be used as rootstocks include Echinopsis, Harrisia and Hylocereus, make a straight horizontal cut through the stem of the rootstock at the required height, then remove the rib margins with a sharp knife to form a bevelled edge and trim off any spines near the cut, prepare the scion in a similar way and position its base on the cut surface of the stock plant, place elastic-bands over the top of the section and under the base of the pot to keep the scion securely in place, making sure that the bands are not too tight, leave the grafted plant in a well-lite position but not in full sun, keep the compost barely-moist until the scion and the stock have united (normally in one to two weeks) when the elastic-bands may be removed, thereafter, water and feed as for established plants. When grafting Asclepiads, the fleshy tubers of Ceropegia or the robust stems of Stapelia may be used as rootstocks, the former, in particular, make excellent stock plants for some of the Madagascan and Arabian Asclepiads which may otherwise be difficult to propagate. Side-grafting; This method is useful if the scion is too slender to be grafted onto the top of the stock, it is very similar to spliced side-grafting, used for woody-plants, prepare the stock by slicing off the top at an oblique angle, then trim the base of the scion to match the stock as closely as possible, secure them together with a spine or raffia and treat as for flat-grafting. Note; All information coincides with the guidelines of The Royal Horticultural Society.
Posted on: Mon, 30 Sep 2013 23:04:05 +0000
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