How to take root cuttings - pushing the cuttings into the compost

How to take root cuttings

BBC Gardeners' World Magazine

Published: Wednesday, 28 August 2019 at 4:40 pm

We show you how to take root cuttings from plants such as phlox, primulas and Oriental poppies.

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Taking root cuttings couldn't be easier and it's the ideal way to increase your stock of perennials, such as phlox, rhus, mint, Japanese anemones and Primula denticulata.

There are two ways to grow root cuttings: vertically for thick-rooted plants such as verbascums and poppies, and horizontally for thin-rooted plants like Japanese anemones and phlox. We've shown you how to do both.

Take your root cuttings while the plant is dormant. Generally this is from around November to March, but in some spring-flowering plants enter dormancy earlier in autumn and come into flower early the following year.

You will need:

Garden fork, For plants in the ground
Sharp knife
Large pots
Gritty compost mix, Made from equal parts grit or perlite and potting compost
Label and pencil

Total time: 30 minutes

Method for thick-rooted plants, such as verbascums, Oriental poppies, anchusa, acanthus and sea kale

Step 1:

Expose the roots of a plant in the ground or take a new plant out of its pot. Select roots that are young, pale brown and slender – about 5mm thick.

Exposing the roots of sea kale

Step 2:

Trim off any hair-like roots and slice the main root into pieces. The length of these isn't crucial – if you're planting them into modules, cut them to the module depth.

Dividing the root into pieces

Step 3:

Line up the cuttings so you can keep track of which is the top (the end that was closest to the crown of the plant) as they won't grow if they're upside down. Fill module trays with a loam-based compost mixed with grit.

Lengths of root

Step 4:

Insert one cutting per module, vertically, and push it in until it's flush with the compost surface. They'll root just as quickly in a seed tray, but will be easier to pot up from modules and will suffer less root disturbance. Expect to see leaves developing on the top of the cuttings after a month or so, but wait a further few weeks before potting on – new roots develop after the leaves.

How to take root cuttings - pushing the cuttings into the compost

Pushing the cuttings into the compost

Method for thin-rooted plants, such as Japanese anemones, phlox and hardy geraniums

Step 1:

Expose some roots of your chosen plant using a hand fork. Those on the outside of the clump will be the most vigorous. Or, lift a whole clump using a garden fork, select the best roots and cut off near the crown of the plant.

Dividing the root into lengths

Step 2:

Slice the roots into 5-10cm lengths – the thinner the root, the longer the cutting should be. They'll dry out quickly, so don't delay potting them up. Fill a seed tray with a loam-based compost mixed with grit.

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Dividing up the roots into sections

Step 3:

Lay the cuttings on the surface of the compost and press them down firmly, keeping them horizontal and making sure they're in close contact with the compost. Hold them in place with a covering of horticultural grit, which also helps retain moisture and provides drainage. Water well, from above, to ensure they're nestled in happily, but always use a fine rose to ensure nothing gets washed away.

Laying the cuttings on the compost

Step 4:

Most of the cuttings will develop new leaves along the surface of the root after a month or so. This helps to produce a bushy plant from the start. Wait a further few weeks before separating and potting on.

Newly developed leaves

The right way up

Thick roots can be pushed vertically into planting holes made with a pencil. Make sure they go in the right way up. Roots will form at the end that was furthest away from the parent plant, so this end should sit in the bottom of the planting hole.

Watering can

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