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.
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Follow the easy steps in this guide to propagating plants by taking root cuttings.
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
Method for thick-rooted plants, such as verbascums, Oriental poppies, anchusa, acanthus and sea kale
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.
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.
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.
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.
Method for thin-rooted plants, such as Japanese anemones, phlox and hardy geraniums
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.
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.
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.
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.
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.