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Re: Root Cuttings

On, 12/28/96, Duncan wrote:

>I have never tried root cutting process in a large scale. I have taken
>classes from the Rhododendron Species Botanical Garden  and they taught
>us about softwood cuttings and  how to select  the  species for a nodal,
>basal, internodal, single  and hell cutting.   What plants do you
>propagate by cuttings and why? Is a cutting much easier to propagate
>than germinating a seed?

Hello everyone!

I know this post from Duncan was a long time ago, (and that may tell you
just how far behind I am on my mail), but I since I just finished writing an
article on this subject, I thought you all might be interested in it and
have posted it below.

I love doing root cuttings. They are so easy, and you can do masses of them
in such a small space, which is great for nursery propagation. I would be
most interested in any recommendations for other species that take well this
way, especially rock garden plants and alpines. (See the list at the end of
my article). Amber 

PROPAGATION LECTURE SERIES PART 6:  ROOT CUTTINGS 
(By Amber Hearn)

Tonight we will begin talking about increasing plants from cuttings, and
thankful I am to be done with the seed germination topic as I've never
written anything so difficult in my life. I'm still not sure I covered it
adequately, and keep thinking of things I should have said.  Perhaps
sometime when I'm feeling up to the task, I will put it all in a book. In
the meantime, we will move on, and I will cross my fingers that I have not
totally confused everyone, or scared anyone out of trying to grow plants
from seed. Cuttings are a much simpler subject to write about, as there are
not nearly so many variables involved.  

Most texts on cuttings begin with stem cuttings,  but we will begin our
discussion of cuttings with root cuttings for two reasons. One is that it is
the right time of the year to do root cuttings and I feel it is appropriate
to talk about them while you can actually go out and practice.  Two, second
only to division, root cuttings are the easiest method, available to the
home gardener, for increasing stock of many plants.  If you find that
surprising, consider that, beyond seeds, this is one of natures most common
ways of ensuring survival. What happens if you yank a dandelion or bindweed
from your garden and don't get every piece of root, or even worse, try to
get rid of a patch of weeds by tilling them under? The same happens after
natural disasters such as mud-
slides and floods.  Every little piece of root left takes hold, and forms a
new plant identical to the old one. Realizing that this doesn't just apply
to noxious weeds, and in fact can be said to be true for many plants, we can
use this wonderful little facet of science to our advantage.

This is probably my favorite method of cuttings as it is so easy, and
applies to so many different plants, including trees, shrubs, alpines,
perennials, etc. To be specific about which ones, you can either buy a text
that will tell you what plants are the best subjects, or experiment on your
own. (I've included a partial list below) In addition, there is no need to
purchase expensive  equipment and most subjects can be rooted without even
having the benefit of a cold frame. There are, however, some guidelines to
follow to ensure a better success rate. After all, if you're going to go to
the trouble of digging up a plant and stealing some of it's roots, it'd just
as well be a rousing success. 

The first order of business, is to prepare a cutting soil, also called
medium or compost,  to insert (strike) your cuttings in after collection. As
with seeds, the cutting medium is there more to hold the cuttings in place
and to provide moisture than for anything else. Cuttings, not being complete
plants, are incapable of photosynthesis, and cannot process food, so the
medium need not
contain any nutrients.  It is best to provide a free draining mix that stays
reasonably  moist, but not soggy, as cuttings of any type will be more
likely to rot in a very wet medium. The usual recommendation is a mix of 1
part peat and 1 part coarse sand or grit. For some subjects, such as finicky
alpines, you may want to go with 1 part peat to 2 parts grit for even freer
drainage.  Some growers do away with the peat altogether and use just coarse
sand, but this dries out very quickly, and requires more attention from the
grower than I have to give.  One important note, you must prepare fresh soil
for each batch of cuttings. Reusing old soil is asking for disease
transference, and I find that old soil is much more prone to fungus and
mold. Once you have prepared the mix, go ahead and fill you containers 2/3
to 3/4 of the way full and moisten the mix. 

What containers? This is up to you. I find that seedling flats make
excellent flats for root cuttings because they are easy to work in, but you
can use just about any size pot or flat, providing it has good drainage.
There are even some cutting flats on the market designed specifically for
this job. Barring all of this, it is also OK to insert the cuttings directly
on the floor of a  propagation case or cold frame. Just put the mix on the
floor, and insert the cuttings into it.

The only other tools you will need are a very sharp knife (I prefer a razor
blade or exacto hobby knife) and a spading fork or shovel.  Take with you to
the garden, a magic marker and clean polyethylene baggies in which to store
the cuttings during collection. This prevents them from drying out.  

It is recommended that root cuttings be taken when the plant is dormant, to
prevent damage to the parent plant.  If the plant is in full growth, it is
much more susceptible to damage. In addition, the wounded parent plant is
less likely to become infected by underground pests and root rot if root
snipping is done when the soil is cold.  Having said that, I might also say
that I've had very
good success starting  the root pieces left when moving plants from place to
place in spring and fall, but I probably wouldn't dig a plant at the wrong
time just to take root cuttings. 

Either dig up the parent plant completely, or just remove enough soil along
one side to expose a good portion of roots. The thickness of the roots you
select will vary with the species of plant you are collecting from. Some
plants, such as Papaver and Stokesia, have thick fleshy roots, and you can
take pieces that are about the thickness of a pencil, while others, such as
Phlox paniculata or Linum have very stringy roots, and will be much smaller.
In either case, examine
the root system. You do not want to take the fresh fibrous feeder roots, as
they will not root, and in any case would cause undue harm to the plant.
Neither do you want older woody roots, as they are slower to take. Select
firm, healthy roots, preferably from the previous seasons growth. With your
knife, make a cut at the top of the root, near where it meets the crown or
base of the plant, but not so close as to cause damage. You may also use
pruners or secateurs, but you will need to re-cut with a knife later if you
do. Carefully free the root from among the root mass, avoiding tearing or
breaking it up too much, and trying also not to stretch it, as this will
also cause cell damage. Remove several roots from the parent as desired, but
keep in mind that you don't want to damage the parent too much. Usually 4 or
5 roots are plenty, as they are further cut into smaller pieces. 

When you are done, carefully replant or recover the parent with soil, and
tamp it in firmly. If the soil is dry, you will probably want to give it a
drink to ensure that all the air pockets are filled. In addition, if you
live in a climate like mine, with repeated freezing and thawing during the
winter months, it isn't a bad idea to put a nice layer of mulch around the
plant to keep it from heaving out of the ground.  

Before moving on the next plant, I take my black magic marker, label the bag
with the varietal name and make a mark at the top end of each root. This is
the end that was closest to the crown or base of the plant, and is
technically called the proximal end.  The bottom is, the one farthest away
from the plant is known as the distal end.  It is important to know the
difference between
the two when striking the cuttings. Not because it has any effect on whether
or not they will take. It doesn't.  But because, although you may not be
able to tell the difference, the plant can, and will always commence foliage
growth from the proximal end, and root growth from the distal end. If the
cutting is inserted upside down in the pot, both ends will have to turn and
grow the
other direction. This makes for growth that is very easy to damage when
potting up, and in the case of woody subjects, some very ungainly trunks. 

Back in the warmth of your home or greenhouse, remove the roots from the
bags, one species at a time, and wash them gently in cool water to remove
all of the garden soil, and any lurking insects. Then, with a sharp knife,
cut the pieces in to lengths approximately 2" (4-5cm) long. Make the
proximal cut straight across, and the distal cut on a slant. Again so you
can tell the difference when inserting them. It is not necessary to dip them
into a rooting hormone before
insertion, but most growers do shake the cuttings in a bag of powdered
fungicide to help prevent them from rotting. I use the rooting powder as it
is mostly fungicide anyway, and I don't like using many chemicals. 

Your cuttings are now ready to insert. Here you have a couple of methods
available to you. Thick pieces can be inserted vertically in a pot around
the rim as you would a stem cutting.  I make a hole the approximate length
of the cutting and push the cutting down into it, making sure that it
reaches the bottom, then pinch the soil in around the cutting to make sure
there are no air
pockets. Make sure that if you insert your cuttings in this manner that the
slanted end, which should be the bottom (distal) end is inserted first. The
cuttings are inserted about 2" apart to allow for root growth and ease of
later pricking out. After the flat or pot is finished, I dust the top of it
with about 1/4" of medium and water it in again.  Then I top dress it with
1/2" of granite
grit.  

Thin roots are nearly impossible to insert in this manner as they tend not
to want to stay straight, so they are inserted in flats horizontally.  This
is by far the easiest of the two methods, as it can be done with the thicker
pieces as well, and is almost always the method I use unless I have only
enough cuttings for a small pot. Simply fill the flat 2/3 full with cutting
compost and lay the
cuttings in horizontally, again leaving about 2" for root growth. Cover over
the entire flat with a good dusting of soil, and top dress with granite grit
as above.  Then water in with a fine spray from the hose or watering can.
Note that with this method, it isn't necessary to know which end is which. 

After the pots/flats are prepared, the best place to put them while you are
waiting is a cold frame if you have one. The frame should be in bright
light, but not in direct sunlight. I like to put mine on the north side of
our garage.  If you don't have a cold frame, simply bend wires into U shapes
and place in the pot or flats, and cover with plastic sheeting, thereby
making a mini frame. Again, put the pots or flats in indirect but bright
light.  Bottom heat, while not necessary for most subjects, will
substantially decrease the amount of time it takes for the cuttings to root
in, and is something to consider when in a hurry. I like to sit flats of
root cuttings on top of my refrigerator and water heater, under fluorescent
lights to speed up the process, but if you like you can go and buy heating
cables.

While they are rooting, the flats should be kept constantly moist to the
touch, but never soggy. (You shouldn't be able to press liquid out of the
soil by pinching it).  Shoots will often appear within a few days or weeks
after insertion, especially if the cuttings are in a warmer climate than out
of doors. Do not take this to mean that the process is finished, as the
shoots are usually the first things to grow. Wait until spring, or at least
until you see the root tips beginning to stick out of the bottom of the flat
before potting on and hardening off. 

Remember that the medium you use contains no nutrients, so as soon as the
plants are solidly rooted, you should either pot them up to a good soil or
add  a little food to the medium. Keep in mind that the plants are tender,
having grown under protective cover, and will need hardening off to the
elements before planting out. You can do this by putting them in a cold
frame, with the cover (the British term for cover here is lights) off during
the day, or by planting them in a nursery row with a protective row cover on
during the night and stormy or windy days. If you inserted your cuttings
directly on the ground, you can of course just leave them there until you
are ready to put them in the garden, but remember that the plants are only a
few inches apart, and will soon become overcrowded.  Also when you move
plants rooted directly in the ground, remember that each little piece of
root you leave behind when you move them is  potentially a new plant. This
can result in a real mess for your next bunch of cuttings if you aren't careful.

That's all there is to it, and since I have a bit of room left, I'm going to
fill it with a list of plant genera that are normally suitable for this type
of propagation. (I apologize in advance for only using the Latin names in
some cases, but to be frank, I really don't know many of the common ones).
Don't take this to be the final word, as it is only a partial list. Go out
and experiment. I can't count the times I've rooted something you weren't
supposed to be able to according to the texts. 

Acanthopanax, Achillea (Yarrow), Aconitum (Monkshood), Aegopodium, (Goutweed),
Ailanthus (Tree of Heaven, Anchusa (Alkanet), Anemone (Windflower), Aralia,
Arnebia (Prophet Flower), Artemisa (Wormwood), Campsis (Trumpet Vine),
Catalpa (Bean Tree), Catananche (Cupid's Dart), Ceanothus (New Jersey Tea),
Cephalaria, Cladrastis, Clerodendron, Codonopsis, Convolvulus, Coriaria,
Crambe (Giant Sea Kale), Daphne, Dendromecon (Tree Poppy), Dicentra
(Bleeding Heart), Echinacea (Coneflower), Echinops (Globe Thistle),
Embothrium (Chilean Fire Bush),  Epilobium, Eryngium (Sea Holly), Euphorbia
(Spurge), Gaillardia (Blanket Flower), Gentiana (some species) Geranium
(Crane's Bill), Gymnocladus (Kentucky Coffee Tree), Gypsophilia (Baby's
Breath), Helianthus - perennial species (Sunflower), Houttuynia (Chameleon
plant),  Humulus (Hops),  Hydrocharis  (Frogbit), Koelreuteria (Golden Rain
Tree), Limonium, Linum (flax), Macleaya (Plume Poppy), Oenothera (some
species) (Evening Primrose), Papaver (Poppy), Phlox, Physalis (Chinese
Lantern), Pulsatilla (Pasque Flower), Rhus (Sumac), Romneya (Tree Poppy),
Sorbaria, Stokesia (Stoke's Aster), Symphytum (Comfrey), Verbascum
(Mullein), Verbena (Vervain)

The next lecture will continue on with the subject of cuttings. 
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Amber & Wayman Hearn                    jadare@accessus.net
Whippoorwill Creek Nursery              USDA Z-5
943 Foxville Road                       mintemp = -15F/maxtemp = 102F
Kell, IL 62853
618-822-6000
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