WTF is propagation?

Welcome to my WTF Gardening series, where I take common gardening terms and explain them for those who are new to the world of plants. Find the entire WTF Gardening series here.

In this blog, I’m talking about propagation. The word ‘propagation’ has lots of different meanings, but in the plant world it refers to the process of plant breeding!

You might have seen this word pop up on YouTube or Instagram, where growers have expressed their delight at having propagated their succulent/monstera/fiddle leaf fig (delete as appropriate). What this means is that they’ve created a brand new plant from one or more parent plants.

 

 

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“So, if that’s the case,” you wonder, “why should I ever need to buy plants again?”. Well, the thing is, propagating can be a little difficult to master. Different plants can be propagated in different ways with varying success, and newly formed or ‘baby’ plants have different needs to their adult counterparts – so it’s easy to get it wrong.

However, that shouldn’t put you off from giving propagation a go! You never know: you might have a hidden talent for it!

The two different types of propagation

There are two types of propagation: sexual and asexual. 

Sexual propagation

This is a natural process which involves the pollination and fertilisation of two parent plants to create a new plant. In most species, this new plant grows from a seed, however, sexual propagation also includes plants that grow from a spore (for example, ferns, algae, moss and liverworts). 

Sexual propagation allows for ‘genetic diversity’, which means that plant breeders can select the best traits from parent plants (like colour, size, hardiness, and more) and use those to create improved plants. In nature, genetic diversity allows the natural continuation of a plant species through ‘survival of the fittest’; plants that adapt to changing environments survive and create new plants with the same traits, while those that don’t adapt simply die off.

F1 hybrids – a type of sexual propagation F1 hybrid seeds refers to the process of ‘selective breeding’ by cross pollinating two different parent plants. This produces ‘F1 hybrid seeds’, which carry the dominant characteristics in each parent, but they’re not identical to either parent. To create every new batch of F1 Hybrid seeds, you need to copy the original hybridisation. So that’s why F1 Hybrid seeds are labour intensive to create, and expensive to buy!

Asexual propagation

This process occurs when a plant reproduces without fertilisation.

Vegetative reproduction is a branch of asexual propagation, where a new plant grows from a single parent plant’s vegetative parts (e.g. its leaves, stem or roots). This can be a natural process, or it can be achieved artificially – the latter is the type that you’re more likely to see your favourite plant influencers displaying on their social media!

Plants that are created using asexual propagation are usually clones of their parent plant. 

Methods of asexual plant propagation that you can do at home

Fancy having a go at propagating your own plants? Try one of these methods:

Cutting

Propagation using this method involves cutting a piece from a plant, and planting it to create a new plant. 

Best plants for taking cuttings:

There are so many plants that can be grown from cuttings, so the best thing to do is research particular plants beforehand. Plant cuttings can be grouped into four categories, with some falling into more than one: softwood (from fresh, new growth), greenwood/herbaceous (from plants with non-woody stems, e.g. annuals), semi-hardwood (from tougher, more mature stems), and hardwood (tough stems that are dormant; usually taken in late autumn or winter). Here are some plants from these categories:

• Buddleia (softwood)
• Hydrangea (softwood)
• Rose (softwood)
• Boxwood (greenwood)
• Dahlia (greenwood)
• Gardenia (greenwood)
• Azalea (semi-harwood)
• Camellia (semi-harwood)
• Honeysuckle (semi-harwood)
• Angel’s Trumpet (hardwood)
• Fig tree (hardwood)
• Viburnum (hardwood)

 

How to do it:

• Make sure your parent plant is healthy and showing stable signs of growth. The best time to take a cutting is in early spring and, if you want to be really specific, the morning after watering, when the plant has absorbed plenty of water.
• Use a clean, sharp knife, scissors or secateurs to take the cutting. Do not use a tool that has been used to cut back diseased plants, as the disease can transfer to your parent and baby plants.
• Choose a shoot near the top of the plant which is growing to one side, and that doesn’t have buds or flowers on it (this will allow the energy to be put into growing new roots rather than flowers).
• Cut the shoot off with a straight cut, rather than at an angle.
• Plant your cutting in a pot with levelled-out compost and remove the lower leaves if they are touching the soil, as they will likely rot anyway. You can dip the end of your cutting in rooting hormone to improve successful root growth – just make sure to tap off any excess.
• Water your cutting, and cover it with a clear plastic bag – or in a greenhouse, if you have one – to help prevent it drying out. Place it in a location with plenty of indirect light. Maintain this environment until your plant has rooted (around 6-8 weeks).

Division

You can propagate plants by division if the parent plant produces bulbs, tubers or rhizomes. There are many plants with these characteristics, so again, it’s best to research beforehand!

The method of division depends on the type of plant. Here are some helpful videos for each type.

Bulbs (example – Daffodils):

Tubers (example – Dahlia):

Rhizomes (example – Sansevieria Whale Fin):

Plants with stolons can be divided for propagation too – all you have to do is cut the stolon at the base of the baby plant, and all the back to the main plant, or the next baby plant.

Stolons (example – Spider plant):

Layering

This method of propagation involves the stem of a parent plant forming roots while it is still attached. It is best carried out in spring or autumn – for deciduous plants, spring is best. There are different types of layering, including tip, simple, compound, mound and air layering; these all follow a similar format.

Tip layering:

This works for plants which have shoots that grow towards the ground, like raspberries and blackberries. The tips of the shoots develop roots once they reach the ground, then grow new plants.

Simple layering:

This is for plants with flexible, low growing stems. The stem is bent to the ground and staked in place. Part of it is covered with soil, while the tip is left free. If necessary, you can wound the stem at the bend and apply a rooting hormone. The new plant will then grow in the bend beneath the soil.

Compound layering:

The entire stem of a plant is forced horizontally, secured in place and covered in soil or a propagation medium. Multiple new plants grow along the length of the stem. For quicker propagation, you can wound the main stem and apply a rooting hormone where you want new plants to grow.

Mound layering:

This is for plants and trees with thicker, less flexible stems. The lower stems are wounded above the trunk/main stem to produce lots of new buds. The following spring, soil is mounded over the new shoots, and roots start to develop. This is a very popular method with growers of fruit trees.

Air layering:

The main stem or trunk of a plant\tree is wounded and rooting hormone is applied. The wound is then wrapped in moist sphagnum moss, and then further wrapped with a plastic layer (preferably black or opaque, to discourage the growth of algae). The plant is left like this for a period of time (depending on the species) while it develops roots. Once ready, the top of the plant is then cut off just below the rooted section, and transplanted to a pot to grow on its own. The original plant will continue to grow. 

I cover air layering of Dracaena marginatas, a popular houseplant, extensively in this post.

 

What would you like to learn about next in the WTF Gardening series? Let me know in the comments below!