One of the most satisfying things you can do is propagate your plants. You get to increase the stock of your favourite plant for free. And you get the most tremendous sense of achievement. Indeed I’ve previously blogged about taking salvia cuttings and I’m forever dividing my perennials such as sedums, achilleas and phlox. But, what I’ve not talked about much before is, for me, one of the most magical, almost mystical ways to propogate plants – by root cuttings.
So I’m devoting today’s blog to this technique. After all, this is the perfect time of year to give it a go.
What Root Cuttings To Take and When
Root cuttings are best taken when plants are dormant – November through to March. This makes perfect sense when you think about it as you don’t want to put extra strain on a plant by disturbing its roots to take cuttings, when it’s trying to grow and bloom.
Sadly, not all plants are suitable for propagating in this way. It’s ideal for certain perennials – verbascums, oriental poppies, campanulas, phlox, Japanese anemones, anchusa and acanthus.
With the thinner rooted plants like phlox, campanulas and Japanese anenomies you lay the root horizontally. For the lovely fat, rubbery roots of verbascum and oriental poppies you use the roots vertically.
How to Take Root Cuttings – The Vertical Method
Root Selection and Preparation
- Lift the plant (verbascum or oriental poppy) using a fork – you don’t want to damage the plant in the process of doing this and remember to return it to the ground as soon as you can afterwards
- Choose a younger root – they’re usually pale brown – those closer to the crown of the plant are the most vigorous
- You want to select a root that’s about 5 mm thick, like a slimmish pencil
- If there are hair roots on your selected root, trim these off
- Then divide your root into chunks – the length doesn’t matter too much, as it’s dependent on the container you are putting it into. I’d say 1.5-2 inches. It needs to be a long enough section of root to contain the carbohydrates to sustain and get the new plant going.
- It’s important to know which is the top end of your cutting (the end which was closest to the plant above ground). As the cuttings won’t grow if you plant them upside down!
- To know which end is which I line the root cuttings up carefully as I cut them, and as an extra precaution I cut the bottom end of each cutting at an angle.
Line up the cuttings – remembering which end is up!
Planting
- The root segments are grown in seed trays, pots or modular trays. Fill these with a loam-based compost mixed with plenty of grit or perlite. You won’t want the cuttings to be boggy and you want a mixture that the new young roots can easily develop and spread in.
- I use modular trays as I think there’s less disturbance to roots when it comes to potting things on.
- Insert one cutting per module, vertically – bottom side down. Push it in until it is level with the compost surface.
- Water a bit and keep the tray somewhere cool. I don’t have a cold frame so I use a cool windowsill
- Then be patient and wait!
- Leaves will miraculously appear on the top of the root after a month or so. It’s absolutely fascinating to watch. If you do this with kids they’ve love it!
Potting On
Don’t rush to pot on. Leave things for seveal weeks. In fact, assuming the plant cutting doesn’t become huge, I’d possibly wait until spring before potting them on. That’s because the new roots develop after the leaves. You want to be really sure your cutting has had time to develop a good root system.
When I pot them on I will put them in a decent size pot and grow them on in pots – outside – for a year, before planting out in the garden the year after that.
The Horizontal Method
Certain plants like campanulas, phlox and Japanese anemones have much thinner roots. For them you need to use the horizontal method.
In essence you lift your plant and again select a young looking root, near the crown of the plant and trim off the hairs. But this time you will lay your chunks of root horizontally under about 1cm of the compost. As the roots are thinner, to provide your cutting with the same level of sustenance, you need a longer section of root – probably about 3 inches. So you obviously won’t have the space to grow them in a modular tray and will need to use a pot or a seed tray.
Otherwise, the process is the same.
My Root Cuttings
I have a huge stock of phlox, a really gorgeous variety called Mount Fuji. It grows over a metre tall and has a lovely fragrance. Much as I love it, I really don’t want more of it. Indeed, if anything I need to reduce my clumps of phlox through division (which I’ll do in early spring before the new growth begins) and give the spare plants away!
I also don’t need more campanula. I have oodles of it, growing like a weed. It even comes up through the cracks in my patio. I love it but I don’t need to actively propagate it.
The one plant I definitely want more of is oriental poppies. In my sunny bed which is next to my patio, I thought it would be oh so lovely to have a few oriental poppies of the variety called Coral Reef, rising majestically among the roses, gypsophila, echinaceas and campanulas.
So when I planted up the bed years ago, I put in five of this lovely plant. However, only one survived. It was handsome but looked rather lonely with its solitary bloom. Rather than fork out for more, I thought I’d increase my stock of this one healthy plant by root cuttings. That was four or so years ago and I’m happy to say I’ve gradually increased my supply ever since.
Today I have a decent swathe of the poppy in the bed, (above) but I’d still like more. So in early November – as part of my November gardening jobs I took some further root cuttings. I followed the process I’ve described and these have just started to take. Can you see the teeny-tiny leaves below?
So do have a go yourself. Or when you next buy one of these plants take a cheeky root cutting before you plant it out. You too could become root cutting mad like me! Happy gardening x
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