Propagation techniques

Propagating plants is a rewarding and fascinating process to obtain new plants. Select the appropriate method and timing then follow some basic principles to ensure success.

Propagation equipment for cuttings

Propagation equipment for cuttings

Quick facts

Suitable for: Various
Timing: Various
Difficulty: Easy, moderate and difficult depending on task

Seed propagation

Most plants can be grown from seed using a variety of methods. Remember though that many will not ‘come true’, that is demonstrate the characteristics of the plant you collected them from.

See our page on seed collection and storage.

Seed sowing - indoors

Some seeds require a warm and protected environment to germinate or you may want to get a head start for the growing season by sowing under cover and protecting your crop from an unpredictable spring.

See our page on seed sowing indoors.

Seed sowing - outside

If you do not have a greenhouse or are short of window sills, you can sow outside once the soil has warmed up. You will save space this way and in fact some plants prefer direct sowing.

See our page on seed sowing outdoors.

Seeds of trees and shrubs

Tree and shrub species sometimes have specific germination requirements such as a chilling period to mimic winter. It’s best to research each species for best results. Often seeds from trees and shrubs require more time to germinate.

See our page on trees and shrubs from seed.

Vegetative propagation

Vegetative propagation is useful for increasing stock of named cultivars which don’t come true from seed. Use these methods to produce cloned copies of the parent stock.

Hardwood cuttings

Suitable for many deciduous climbers, trees and shrubs as well as evergreens. Take cuttings in the dormant season, however each plant will vary so check individual requirements.

See our page on hardwood cuttings;

Softwood cuttings

Suitable for a wide range of mainly deciduous shrubs, trees and hardy or tender perennials. Take softwood cuttings in spring and early summer selecting soft flexible tips.

See our page on softwood cuttings.

Greenwood cuttings

Suitable for berry fruits, Ceanothus, Forsythia and Philadelphus. They are similar to softwood cuttings but the base of the stem is firmer. Prepare as softwood cuttings, but make them slightly longer, generally 7.5-12.5cm (3-5in) long. Take later in spring through to mid-summer.

See our page on softwood cuttings.

Semi-ripe cuttings

Many plants are propagated using this method. The cutting base is quite firm, whilst the tip is relatively soft. Take semi-ripe cuttings in late summer to early autumn when sections of the current season’s growth has begun to firm.

See our page on semi-ripe cuttings.

Heel cuttings

This method is useful for woody plants that have pithy stems, such as Sambucus (elder), or old plants in less than peak condition. It is not very effective on broad-leaved trees.

Pull away a cutting-sized shoot from the main stem, to retain a small tail of bark, or heel, at the base. The heel contains high levels of growth ‘hormones’ (auxins) that help promote rooting.

Root cuttings

Some plants have thick fleshy roots, which make great cutting material. Lift plants during the dormant season.

See our page on root cuttings.

Leaf cuttings

Some plants can be propagated from a whole or a part of a leaf. It is an easy way to increase numbers of our favourite indoor plants.

See our page on leaf cuttings

Presenter, writer and gardener Ellen Mary, shows you how to propagate your houseplants by taking whole-leaf cuttings.

Layering

For producing one or two new plants, simple layering is aeffective for many shrubs. In autumn or spring (evergreens are better in spring) select supple shoots on the outside of the plant for pegging down.

See our page on layering.

Air layering

Use air layering for plants with brittle wood that won’t bend for tradition layering or where there are no low growing shoots.

See our page on air layering.

Grafting

A method that combines material from one plant with prized flowering or fruiting qualities with the roots of another that offers vigour and resilience. This is a difficult task and requires lots of skill and practice. In most cases, trees and shrubs are available to buy ready-grafted onto a rootstock. Most tree fruits and roses are grafted.

See our page on grafting.

Division

Many herbaceous plants are propagated by division – the separation of one plant into several self-supporting ones.
Split clumps into sections, each with at least one shoot and a root system of their own. Carry out in spring or autumn depending on the preference of the plant and overwintering conditions.

See our page on dividing perennials.

Micropropagation

The culture of plant cells within sterile laboratory conditions using high tech equipment to produce clonal copies of plants.

See our page on micropropagation.

Bulb propagation

Cuttings from the stems and leaves of bulbs will fail as the growing point is inside them. Many bulbs produce offsets, which are bulbs produced from basal plate of the existing bulb. Remove and pot up to increase numbers of your favourite bulb. To create greater numbers, use methods such as chipping or scaling.

See our page on bulb propagation.

Practical considerations

Collecting material

Before collecting any plant material for cuttings the following need to be taken into consideration.

  • Use clean tools and equipment during propagation (including surfaces). High standards of hygiene are important for success
  • Collect material early in the day when full of water (turgid) to avoid wilting. Ideally remember to water the plant the day before
  • Do not select pest-or disease-damaged material
  • Remove material with a sharp pair of secateurs, placing cutting material into clean plastic bags with a label
  • Once collected place cutting material in a fridge if it is not to be prepared immediately. Add a splash of water to keep slightly moist

Compost/growing media

There is a selection of ready-made cutting composts commercially available. They are free-draining using materials such as composted bark, sand, coir and perlite. This helps prevent rotting in humid propagation environments and provides air spaces creating a healthy growing environment for new roots. They are also low in nutrients as young plants have little use for them at this stage.

Wounding

Not all plants root easily from the methods above and some tricky plants such as Ilex, Camellia and Rhododendron, require wounding to encourage root production. It is thought that wounding creates a root promoting stimulus, perhaps of a chemical nature.

Prepare your cutting then remove a thin slice of bark near its base. The length of the wound will depend on the size of the cutting but a rough guide of 1cm (½in) can be applied. This creates a larger surface area for forming roots.

Rooting environment

Once the cuttings are in their pots and ready to grow, get them off to a good start by proving the ideal growing conditions.

  • Place in good light, avoid scorching direct sunlight. Diffuse bright light with a layer of fleece
  • Keep undercover in a propagator or greenhouse with bottom heat, to keep the cuttings warm and humid
  • A pot with a plastic bag over the top kept somewhere light and warm will also suffice
  • Vent cutting daily, by lifting the lid or plastic bag. This prevents cuttings from getting overly wet and stagnant, reducing fungal disease risk
  • Watering will vary between species, as a rule keep moist in summer and only water once the compost is dry in winter
  • Remove dead and diseased cuttings to reduce further contamination
  • Pot on cuttings once they show signs of strong active growth from roots and new shoots

Hardening off and aftercare

Once the cuttings have been potted on they will need hardening off before they can be moved out into the garden. This is done by gradually acclimatizing them to outdoor conditions for 2-3 weeks. It should not be rushed, as natural waxes coating the leaves must undergo changes in form and thickness to reduce water loss and toughen to withstand the wind.

Refrain from overly watering newly potted plants, as their new roots are vulnerable to rotting before fully establish within the pot.

Problems

Young cuttings and seedlings tend to be affected by fungal diseases such as Botrytis (grey mould) and powdery mildew and damping off. However these can be largely avoided by good hygiene and air circulation.

Pests such as aphids can stunt and deform growth and fungus gnats (sciarid flies) can feed on the base of seedlings and cuttings. Check regularly to prevent infestations.


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