Manufacturers

Propagation Techniques

Plants can be propagated by sexual means (seeds) or through vegetative means (cuttings, division, grafting)

Seeds

A seed is a complete plant in embryo, but it is dormant.  Seeds may require some preliminary treatment before germination.

  • Seeds with hard coats will take a long time to germinate unless the seed is pre-treated by soaking for 24 hours in warm water.
  • Scarification may be required by some species, this is where the seed coat is abraded or nicked with sand paper or sharp knife.
  • Vernification may be required for hardy seeds that need to be exposed to frost prior to germination.
  • Incubation at moderate to high temperatures may be required for tender seeds (10-21oC)
For slow germinating seeds use a soil-based seed mix, all other seeds use a soil-less seed mix.  Desert plants require more sand incorporated into mix, bog plants more sphagnum, lime-free for Ericas, etc.  Seeds should normally be covered by their own thickness of seed-mix, very fine seeds should not be covered, and be sown evenly and thinly.  Large, valuable seeds should be sown into plugs or cubes to avoid having to thin out.  The seed-mix should be watered prior to sowing, do not water from the top after sowing as this reduces the aeration around the seeds, only add water from beneath.
Loose sown seedlings should be placed into pots as soon as their first true leaves appear, while plug sown seedlings should be potted on when white root tips can be seen at the edges of the cube.  Hold seedlings by the two leaves, do not grip the stem.

Cuttings

Cuttings in general are not so easy to manage since the material for propagation is wholly severed from the parent plant.  Lacking roots, the cutting has no means of taking up feed and water so is prone to wilting and drying out.  Cuttings can be taken from the stem, the leaf and the root.  Click the link below to see the X-Stream aeropropagator in action:

http://www.nutriculture.com/index.php?option=com_content&task=view&id=39&Itemid=48

Stem

Soft-wood or greenwood cuttings are taken in late Spring as soon as the current years growth begins to firm.  Select a vigorous growth between 10 and 15 cm long and cut straight through with a sharp knife.  If the cutting is taken in the garden or away from the preparation area, drop it in a plastic bag and immediately seal.  When you are ready to plant the cutting, remove lower leaves, cut across stem below a leaf node, dip the base in a rooting hormone (clonex) and insert at least 5cm in a soil-less potting mix or cube.  Water thoroughly, keep under cover (to increase humidity and slow wilting) and give warmth from below.  If you have soil warming cables use these with a good thermostat to prevent overheating and drying out.  If you have a mist/aeropropagator, use this to keep cuttings in good condition and use a good quality tank heater to maintain warm rooting zone. If you do not have these facilities use a plastic bag and wire or a plastic bottle to make a mini propagator which should be placed somewhere warm.  The cuttings will need full day light, if no access to the sun then fluorescent tubes and CFLs should be placed as close as possible .  Once rooted the cuttings can slowly be removed from under cover.

Semi-hard cuttings are taken from wood of the current season's growth as soon as the base has started to become woody.  The cutting is taken with a heel.  Take the cutting firmly, sharply tug down and out.  Trim of excess bark, any bruised tissue and remove any soft, sappy growth at the growing tip.  Dip the rooting end in hormone and plant in soil-less mix as per soft-wood cuttings.  Semi-hardwood cuttings will not wilt as fast as soft-wood.

Hardwood cuttings are taken from deciduous shrubs, trees and climbers immediately after leaf fall, with conifers and broadleaved evergreens they are taken at same time (when neighbouring deciduous drop leaves).  Cuttings of 40 - 60 cm long are taken with a heel as above.  The cuttings should be planted out in a sand lined trench 25cm deep.  The heel should be pressed into the sand bed and at least half the cutting should be berried vertically.  Water well then tread til firm, and after each frost.  Over Winter a callus forms which come Spring will begin to root.  Water regularly in Spring as leaf development will lead rooting and will increase the chance of wilting.


Nodal cuttings may be taken from shrubs or climbers, internodal cuttings from climbers with large internodes, especially grape vines. Select a vigorous stem from current years growth when the plant is dormant, make a clean cut above and below the node and insert the section horizontally in the seed-mix, treat as for tender seeds.  Nodal cuttings should be placed with one nodal bud facing up and the other rubbed out.

Root

Many plants with thick fleshy roots can be increased by root sections.  Parent plants are lifted when dormant, cuttings 2cm thick and 10cm long are taken with straight cut nearest parent, and sloping cut nearest root tip, then the parent is replanted.  Plant the cuttings vertically in pots or seed-beds, with straight cut at the top and sloping cut at bottom, with the tops being 1.5cm below the surface.  Plants with "eyes" on root cuttings must be planted with this bud uppermost.

Leaves

Leaf cuttings are laid flat on a layer of fine sand 7mm thick over potting compost.  The leaf is pinned into position, the mid-rib and main veins are cut no more than 7mm long.  Water well, give plenty of light and young plants will form on the cut nearest the petiole.

Petiole cuttings must be cut cleanly from the parent without bruising the petiole.  Insert the cuttings vertically into a soil-less mix no more than half way.  Water well.


Division

This is the simplest method of increasing plants.  Mainly used on bulbs and herbaceous plants, but also many shrubs, this involves seperating large plants into smaller plants complete with own shoot and root system.

Simple division by lifting dormant or post flower plants and tease the roots apart either by cutting main roots and using your fingers, or two forks back-to-back, or if large and tough enough then simple chopped up with a spade.  If the plant has large leaf area, then cut back some foliage..  Spreading plants will have the most healthy and vigorous shoots on the outside of the clump, so discard old, woody centres.

Woody crown plants need to be lifted, crowns washed to reveal shoots, and cut leaving at least one healthy bud and roots on each portion. Replant in well prepared soil.

Tubers can be propagated simply by cutting into pieces with at least one eye.  Dahlias should be divided carefully when dormancy is broken by cutting vertically so each portion has at least one strong shoot, a portion of stem and one or more tubers.

Rhizomes should be prepared after flowering by slicing into 5 to 8 cm lengths with strong new growth.  Retain youngest sections with one leaf or bud and only needs a few roots.  Plant the rhizome horizontally half below the surface with leaves facing the sun, reduce leaf area if necessary.

Suckers produced from creeping roots  can be dug up when dormant, severed from the parent and replanted elsewhere.  Losses can be reduced by separating in situ and leaving there until the sucker has recovered, produced more roots and then replant.

Layering

This technique is used mainly on woody plants, particularly climbers.  A growing branch is partly severed or constricted into contact with the soil or potting compost, and allowed to root there.  The young plant is then able to form its own roots and support itself prior to being severed from the parent.  This can be carried out at any time of year, but rooting will only occur during the growing season.

Layer a branch by making a slit on the underside about 30cm from the tip at an angle of about 20o penetrating no more than a third through.  Open the slit and peg down into a sand lined hollow with the tip tied vertically to a cane.  Cover and water well.  Allow two seasons growth to root, then sever from the parent and leave in situ for another season before moving.

Pot-layering is ideal for climbers which are pliable but resent root disturbance.  One pot should have medium fill the bottom, while another has the stem threaded through the drainage hole.  This pot is placed inside that with medium with the growing tip sticking out between the rims.  Allow two seasons growth before severing and planting.

Air-layering is used where a branch is not suitable to bend down to the soil, or there is no soil.  A vigorous, upright shoot has a slit made 30cm from the tip, hormone applied to the slit and wrapped in damp sphagnum moss and sealed in opaque plastic.  Bind tightly with tape.  Allow 6 to 9 months for rooting, and once severed, the plant will need careful nursing in close conditions until the root system develops fully.

Stooling is when a woody mother is cut back just above ground level to produce shoots which are then earthed up to induce rooting.  Most of the rootstocks of popular varieties of apple and pears are produced by stooling.

Grafting

Grafting is the joining of the rooting system and main stem of one plant (stock or root-stock) with the shoot of another plant (scion) so that they become one.  The stock and scion must be compatible (closely related) and there must be good contact between the cambium of stock and scion.  Grafting is normally carried out towards the end of  the dormant season.  Stocks should be young, healthy, active and sparingly watered to prevent excessive bleeding.  Dormant scion wood should be taken from strong, one year old woody shoots in Winter for grafting the following Spring.  Keep shoots in good condition by storing in a cool, moist environment bundled together and set vertically in sand near a North facing wall.  Soft or leafy scion material must be kept in humid conditions and used as soon as possible.

Whip and Tongue used frequently for propagating fruit and ornamental trees.  The stock and scion should be 13mm in diameter, with the stock one or two years old.  The scion should be from the middle of  a one year old shoot stored over winter and have four good buds.  Behead the stock 15cm above the ground with a sloping cut about 4cm long.  Make a matching cut across the base of the scion.  A downward cut should be made just below the apex to form an upward tongue.  A similar cut should be made on the scion and bound together and sealed with wax.  Remove any growth from the stock.

Saddle grafts are suitable where the stock and scion are similar in diameter, and is mainly used for rhododendrons.  A wedge-shaped piece of wood is cut from the stem to leave an inverted V and the stock is cut to fit.  Saddle grafts do not need to be coated with grafting wax.

Approach grafting permits the scion to retain its own rooting system until the union is complete, used mainly with nuts and vines.   The stock and scion are grown in pots side-by-side, a thin layer of wood is removed from the stems exposing the cambium tissue and the wounded surfaces are bound together and sealed with wax.  When the union is complete, the stock's top growth is removed just above the union and the stem and roots of the scion are removed below the union.

Budding is carried out between mid-June and the end of August mainly on roses, but also fruit trees.  Shield buds are taken from about halfway up a strong stem which has flowered by making a shallow upward cut below, behind and coming out well above.  The thin sliver of heartwood should be carefully removed. A T-shaped incision is made on the stock, the corners of the bark lifted and the bud slipped into position.  Any protruding shield rind is cut away at the top of the T before being tied and bound.  Chip buds are taken by making a cut above the bud and sloping down on one side behind it.  A second intersecting cut is made down the other side releasing the psion.  A wedge shaped peice is cut out of the stock to receive the bud.

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