You know that week between Christmas and New Year’s when it feels like time is dilating and contracting at the same time?
When you want to do something but you can’t exactly pinpoint what and why you should do it? And you feel like the slowed down pace of life is equally relaxing and unnerving?
As a gardener, I experience the same kind of temporal no-man’s land between the end of November and the end of February.
The spring bulbs are neatly tucked in the ground. Whatever perennials needed a pruning got one earlier in the fall. And I’ve already mulched my borders for the winter and collected all the dead leaves of the season.
Yet, I still want to spend time out in the garden, and I’m itching for a good excuse to be out there in the cold, damp and gray weather.
Combine this feeling with the fact that nothing motivates me more than making more plants from my existing stock, and I’ve found my reason to go out into my garden in December: propagation.
But can you really propagate plants in the winter?
Yes, my equally hermit friend, you can. You can propagate plants by taking root cuttings in the winter.
If you think this is some kind of unimaginable sorcery, you’ve clearly never tried to remove a mint plant only to have it resprout from small segments of root left behind.
Essentially, when we take root cuttings, we’re mimicking what nature does when it sends runners that re-sprout a few feet away from the mother-plant. The beauty of propagating this way is that it’s not just for plants that send runners. (I’ll elaborate more on this below.)
Why should I bother with root cuttings?
Yes, I understand the confusion. Why should we even bother with taking root cuttings when there are more straightforward ways to propagate plants, such as taking cuttings, division and starting them from seed?
We’ve already covered all of these methods, by the way. Just click on the links above.
Here are some advantages of taking root cuttings.
It gives us a reason to be out in the garden.
We can take the root cuttings in the absolute off-season for gardening, from November until February. This is when the plants are dormant and we can disturb the roots without disturbing the plants too much.
This is also when the level of carbohydrates is concentrated in the roots. As soon as the plant starts pushing out buds in spring, the energy will be redistributed to these sprouts and taking root cutting will be less effective.
Root cuttings don’t require much maintenance.
In every single article I’ve ever written about propagation, I include a section on maintenance and aftercare of the cuttings.
The good news is that root cuttings don’t need much. Since the root sections are dormant, they really don’t require water, save for a bit of moisture every month or so. They don’t have leaves, so they don’t require sun. It’s winter, so they don’t require heat.
It’s basically a set it and (almost) forget it method of propagation.
Root cuttings can give us a large number of plants.
When we propagate from stem cuttings, we have to make sure we get enough leaf nodes to start growing roots and to generate new sprouting.
That’s not necessary with root cuttings, since we’re already propagating the roots themselves. As long as the roots are thick enough to store carbohydrates for growth (we’ll come back to this later), we can take as many cuttings as we want.
It’s a good way to break the foliar infestation cycle.
There’s no trace of foliage in our root cuttings because, well, they’re roots and because we take them in the cold season when the leaves have already fallen and the plants are bare.
For this reason, the likelihood of passing down foliar pests and pathogens is much lower with this method of propagation. This is super useful when we want to share our plants with others without sharing the diseases as well.
What plants can we propagate from root cuttings?
Before we move on to our root cutting tutorial, have a look at the list below. I’ve tried to include as many popular plants as I could find. And you may notice that not all of them send root runners.
Herbaceous plants (Perennials and biennials)
Oriental poppies (Papaver orientale)
Bear’s breeches (Acanthus mollis)
Asters (Doellengeria, Eurybia and Symphyotrichum)
Japanese asters (Kalimeris pinnatifida)
Cardoon (Cynara cardunculus)
Joe Pye weed (Eutrochium)
Tall phlox (Phlox paniculata)
Globe thistle (Echinops)
Barrenwort (Epimedium)
Bleeding heart (Lamprocapnos)
Mums (Chrysanthemum)
Comfrey (Symphytum officinale)
Sea holly (Eryngium)
Windflowers (Anemone)
Japanese anemone (Anemone hupehensis or Anemone x hybrida)
Mullein (Verbascum)
Tooth-leaved primrose (Primula denticulata)
Blue stars (Amsonia)
Colewort (Crambe cordifolia)
Shrubs and vines
Japanese quince (Chaenomeles)
Bottlebrush buckeye (Aesculus parviflora)
Aralia shrubs
Common fig tree (Ficus carica)
Rose of Sharon (Hibiscus syriacus)
Glory bowers (Clerodendrum)
Panicle Hydrangea (Hydrangea paniculata)
Mock oranges (Philadelphus coronarius)
Golden rain trees (Koelreuteria paniculata)
Oregon grape holly (Mahonia aquifolium)
Pussy willow (Salix discolor)
Raspberry (Rubus)
Blackberry (Rubus)
Oregon grape holly (Mahonia aquifolium)
Dogwoods (Cornus stolonifera)
Lilac shrubs (Syringa)
Roses, but only nongrafted ones
Sumac (Rhus typhina)
Bleeding glory bower (Clerodendrum)
Passion vine (Passiflora)
Sophora shrubs
Trumpet vine (Campsis)
Osage orange (Maclura pomifera)
How to take root cuttings
Now that you know what plants will propagate from root cuttings, here’s how to take them step-by-step.
I’m propagating a Joe Pye Weed roots (photo above) and some red raspberries. I’ll show you some photos to demonstrate this method on the raspberries because we can see the roots better.
Step 1: Access the roots.
Notice that I didn’t just say “dig out the roots” because we can do this two ways.
If we’re planning on transplanting the plant OR if the plant is due to die anyway (such as a biennial in its second year) OR if the roots are hard to access any other way, we should just go ahead and lift up the entire root clump.
This will give us better access to the roots and we’ll be better able to see what we’re doing. But uprooting everything is not completely necessary.
I was relocating my Joe Pye Weed (Eutrochium) anyway, so I lifted it altogether.
The second method for accessing the roots is to simply dig around the plant that we’re propagating until we get to roots that are large enough to take cuttings from.
This method is much more practical when we’re propagating large perennials and shrubs, which would be very cumbersome (and totally pointless) to lift.
What roots work best for propagation?
That depends on what plant you’re propagating. I’ve seen the phrase “pencil-thick roots” used a lot in other tutorials, but that’s simply not feasible for most plants.
If you’re taking root cuttings from a mature shrub, sure, you may be able to find roots as thick as a pencil or your pinkie finger. But for herbaceous plants, that’s simply not what we’re working for.
And again, if you’ve ever tried to pull out remnants of mint plants or bear’s breeches, you already know that the thickness of the root is not an indication of how viable that root is for propagation.
Thinner roots will be sufficient as long as they’re thick enough to have stored enough sugars and carbohydrates to withstand winter dormancy.
The roots have to be fleshy (not dry) and flexible (not brittle). If in doubt, use your fingernail to scrape a bit of the protective layer off the root. If it’s white or light green underneath, the roots are alive and ready to use.
Whether you’re taking cuttings in situ or digging out the plant, don’t cut off more than a third of its root system. Taking too much won’t kill the mother-plant, but it might set it back and possibly delay flowering.
And if you removed the entire clump, remember to replant it as soon as you’re done with the propagation jobs.
Step 2: Cut and prepare the roots.
Just like with stem cuttings, we’ll take a longer cut than we need (if available), then divide it into smaller sections. Cut them off as close to the crown as possible. This is where the root is the thickest. And if you’re propagating a shrub that’s planted in close proximity to other shrubs, dig as near as possible to the crown, just to make extra sure you’re taking material from the right plant.
Here’s what I’ve got to work with.
These are a few long roots coiled together. Each root will give us at least a couple of cuttings.
First, we’ll remove the thin root end, if any. Then we’ll cut each root into lengths of about 2-5 inches (roughly 5-12 cm).
Remember it’s all about food reserves (stored carbohydrates). So the thinner the root, the longer the length. Super thin roots such as Japanese anemone, garden phlox or tooth-leaved primrose will need to be on the long side, just to compensate for how thin they are.
Thicker roots, such as those of hollyhocks, bear’s breeches or sea holly can be propagated from shorter lengths.
Once we have our lengths ready, it’s time to clean them up. Remove all the fibrous roots – they’re feeding roots and they will not regenerate. If the roots are gnarly or twisted in weird ways, try to get some straight pieces out of them. (It will come in handy, but it’s not essential.)
Here’s what an individual root cutting will look like:
Step 3: Plant the root cuttings.
Let’s get the propagation containers ready first.
I use regular garden compost with a quarter to a third perlite added to the mix. You can also use horticultural sand, coco coir or vermiculite in place of perlite. It’s really essential to add bulk without adding too much compost that might end up staying too wet.
I then water the soil and press it down to remove any air pockets.
Also, don’t fill the container to the brim at this point because we’ll need to add more soil later. Leave a margin of at least a couple of inches.
Here’s where the fun part starts because this is where root cuttings and stem cuttings differ. With stem cuttings (both softwood and hardwood ones), we would just stick them in the ground vertically. With root cuttings, we’ll lay them on the growing medium horizontally.
That’s why I’m using a long and flat propagation tray. You may also use regular pots or single-stem propagation pots depending on the number of cuttings you’re taking.
Place your root cuttings flush with the soil, making sure you leave about a couple of inches around each one on all sides. Less if fine, if you need the space to fit more roots in, but make sure they don’t touch. New growth can emerge from several places along the root, and you don’t want to cram them too much.
Once all your root cuttings are in place, cover everything up with another layer of potting mix. I’ve also seen other gardeners use grit or sand for this final layer of the “cake.” You don’t need much of a top cover, just about an inch in height should do.
You can water it again, very lightly, then cover it up with some cling foil or a plastic bag. I’m using the lid of the propagation tray.
Step 4: Aftercare for root cuttings.
Just kidding, I told you there would be very little maintenance for root cuttings. All you need to do at this point is place them in a cold frame, greenhouse or enclosed porch to keep them away from the elements – no rain, no snow and preferably no hard frost.
And since you won’t be able to tell what’s in the container until the new growth starts showing up, make sure to label the tray. I’ve added the month too because I’m planning on taking more root cuttings in February.
By next spring, you will start seeing signs of growth. Some plants will grow roots first – straight down – while others will also sprout leaves. Make sure you remove or raise the protective plastic cover once the new shoots appear to make room for their growth.
Remember that these are baby plants, so give them the same treatment as you would baby seedlings. When spring rolls around, try to get them acclimated to the temperature, humidity and sunlight outdoors by exposing them gradually.
You can divide out the new baby plants by-mid spring and move them to their individual containers. Then plant them in the garden – or share them with friends – by the following fall. If the plants have several sets of leaves, you can also skip potting them up and move them straight into the garden.
And as a final reminder, did you remember to put the mother-plant back in the ground and cover the exposed roots? Give it a bit of water to remove the air pockets and help it settle back in.