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Root Cuttings: The Forgotten Propagation Technique · Hydroponics Daily

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  Hello there and welcome back to
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  Hydroponics Daily, your go-to podcast for everything soilless cultivation.
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  I'm your host, Dr. Russell Sharp, the founder of Utrema Limited and a former academic lecturer.
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  And today you could say I'm going back to my roots because we're talking about plant propagation.
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  I used to research plant propagation back when I was a PhD student at East Moorling in Kent.
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  And today we're talking about root cuttings, which are an unusual type of propagation
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  that very few people have actually heard of, but is quite useful for a number of different species.
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  So let's look into it, because some of these plants are quite interesting.
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  So root cuttings are a good method of propagation for species that regularly
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  produce suckers, but the technique is not exclusive to these types of plants.
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  Root cuttings can also be useful for removing a pathogen that is causing a disease
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  on the foliage of the plant, especially if the cutting is sterilised and then
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  allowed to sprout in an area some distance from the diseased mother plant.
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  So say you've got red spider mites or thrips, then this could be a good way
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  of getting fresh plants that are free of that pest.
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  Now, some plants are great for taking root cuttings from, others you simply
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  cannot take root cuttings from them, and some you get variable results from.
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  Okay, so examples of plants that you can take root cuttings from would be sassafras,
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  safras safras albedium albedum
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  easy for me to say i think that's huge isn't that
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  used in root beer or was originally and then it was removed because
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  it was carcinogenic i think that was devil's walking
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  stick aralia spinosa they're two plants particularly
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  suited to propagation via root cutting i've got
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  a couple of foxglove trees in my garden
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  they are the paulonia tomentosa
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  so they're very very beautiful they produce massive displays
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  of purple flowers that my neighbors are very jealous of in
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  the spring and the closely related
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  paulonia elongata which is another foxglove tree that is the fastest growing
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  hardwood tree in the world so a really good plant a tree to plant if you want
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  a tree very to get to a good size very quickly it's the foxglove trees and they
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  can be grown with root cuttings.
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  Then there are three types of tree where the propagation is quite complicated.
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  So the...
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  I've talked in the past about cuttings and how the mature plants,
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  once they've flowered, they become really, really difficult to take cuttings from. So...
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  Once they've had flowers on them like rhododendron, then the genes that are
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  turned on when they become mature makes it much harder for cuttings to be taken.
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  So you want your mother plant to stay in its juvenile form.
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  Now if it has become a mature form, for a few trees you can revert them back
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  into the juvenile form by taking root cuttings first.
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  So the silk tree which has
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  nothing to do with silk albizia gillibrizin aspen
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  which is a very popular forestry tree
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  and tree of disturbed habitats and georgia plume then are propagated straight
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  from root cuttings due to the problems of maturity instead root cuttings are
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  first taken and the shoots produced revert to the juvenile growth form and then
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  you can take shoot cuttings and dramatically improve the rooting capacity.
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  Root cuttings are also useful for hops, whose dioecious sexuality means vegetative
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  propagation is needed to ensure new plants are female and useful in brewing.
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  Could that be used in other plants in the cannabis family? I'm not sure of any
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  legal cannabis work that's been done on root cuttings, but if it can be done
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  on hops, then potentially it can be done on hemp and legal cannabis.
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  For plants that are difficult to propagate by root cutting, it should always
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  be placed vertically with the cutting orientated the way it was on the mother plant.
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  For plants that are very easy to propagate by root cuttings,
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  such as clematis, another popular ornamental climber, the root cuttings can
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  be placed horizontally in the growing medium, so no need to place them vertically.
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  Placing the cutter horizontally is useful as it often results in more than one
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  plant arising from just one cutting.
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  So if you're a commercial clematis grower.
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  Which there are a few are up in Lancashire, I believe, in the UK near Preston,
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  then they probably put them horizontally and then chop them up after that.
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  Now, this is the most important thing when it comes to root cuttings.
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  Unlike stem cuttings, the use
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  of rooting hormones should not be undertaken because
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  the plant is already a
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  root and then putting an auxin hormone on that
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  is going to promote extra root growth is not
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  what you want you want shoot growth and so do not
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  use rooting gels auxin liquids anything
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  like that when you're taking rooting cuttings there
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  will be other potential hormones that could be beneficial
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  i've not looked at the rich literature but there probably are
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  a few maybe gibberellins things like this definitely don't
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  use a growth inhibitor and they should
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  be fairly easy to take because they're planted into the the growing
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  media you don't actually get a lot of water loss
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  from the root cutting so it can sit there and stay there you don't
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  need to worry about dehydration just make sure that the grow
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  medium remains well watered whereas a
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  stem cutting you're always basically just trying to prevent it dehydrating all
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  the time with a root cutting it's pretty much take them plant them and then
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  wait for them to emerge so they're a lot easier just don't use any rooting liquid
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  it's important to note if you're growing a variegated plant,
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  if you take a root cutting as opposed to a stem cutting, you can lose the variegation,
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  especially if it's due to genetic chimerization.
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  These chimeras we've talked about when grafts.
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  Grafting curiosities there was a pest episode on that if you take a root cutting
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  you can lose that talked about pests and disease one of the big pests you can
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  lose by taking a root cutting free your plants of a pest is the nematodes that
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  stem nematodes in flocks and so flocks plants are,
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  root cuttings are very useful in flocks and they're the routine way of doing
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  it because you can remove the stem nematodes that parasitize the plant by doing
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  that and then finally the last thing to say about root cuttings is that if you
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  do take them off a plant in outdoors and then bring them inside,
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  your mother plant may suffer damaging effects because of that.
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  It can reduce the hardiness of things like foxglove trees if you root prune
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  them and remove roots from them, especially as these root cuttings are normally
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  taken fairly late on in the season, closer to the winter, and so they might not be hardy.
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  So just bear that in mind. It'd be really interesting to know
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  if anyone has taken hop cuttings from
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  root cuttings because that's something we're looking at doing something we're doing
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  at the moment we're growing hops in our grow room we've got about 10 plants
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  now but i'd like to get more and more and they're not looking too healthy at
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  the moment i'd like to improve them increase the number of that we've got and
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  so maybe rather than taking stem cuttings all the time when we separate them
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  we could take some root cuttings be interesting to know.
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  If they're successful because the hop growers we
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  speak to and we there are some of our best and
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  most enthusiastic customers they struggle to propagate hops
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  especially their new varieties new varieties
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  are coming out all the time and so if we could take root cuttings that
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  would be a good thing for them so we'll look into that actively if
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  you found this episode about root cuttings interesting then please leave
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  podcast is to check out utreema.co.uk and
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  if you can't spell utreema it's latin for wasabi and then
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  just stick co.uk on the end of that thank you
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  very much for listening if you've got any feedback any comments about root cuttings
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  then let me know i think we could do an episode tomorrow on root pruning that
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  would be a good one getting back to the nuts and bolts of horticulture after
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  a few controversial news stories it's always good nice and relaxing thank you
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  very much for listening it's been an enjoyable one and i'll speak to you again tomorrow goodbye.