How to Propagate Conifers from Cuttings

By David Speth
These first-year cuttings have been removed from the rooting chamber to their individual pots
These first-year cuttings have been removed from the rooting chamber to their individual pots

It’s easier than you might imagine, saves money, and makes the hobby all the more gratifying!

If you are like me, you started out with perennials, constantly having to divide, deadhead and feel like you should be trying out for a body-building competition after wrestling with all the overgrown plants and sometimes weeds. Not to mention avoiding inviting your friends in August since your perennial gardens are beginning to look tired.

I got started in conifers after attending a seminar presented by Gary Whittenbaugh in Grand Forks, ND. I heard this during that seminar: why should someone grow conifers?

  1. No deadheading
  2. No spring or fall clean up
  3. Year-around beauty

I was sold! Once Gary heard that my passion lies with rooting plants or planting up seeds, he fed my obsession with many cuttings, not to mention the numerous hours we spend talking about conifers, which plants do well in my northern frigid temperatures and what conifers do well from cuttings, etc. I feel so fortunate to have such a wonderful friend and mentor.

Now, have you spent all your cash with your spring purchases and need more conifers? Did you know there are some conifers that are easy to multiply by taking cuttings and allowing them to root? Let’s venture into the world of rooting conifer cuttings.

Conifers that readily root by cuttings:

Abies - koreana and balsamea cultivars

Cedrus

Chamaecyparis

Cryptomeria

Juniperus

Picea - some will root fairly easily

Podocarpus

Taxus

Tsuga

Thuja

Cuttings should be taken from healthy plants as these will root better than those from sick or stressed plants.

When and how to take cuttings

Plants have an internal chemistry that changes with the seasons. Therefore, taking the cuttings at the correct time of year is most conducive to rooting that particular plant. As a general rule, conifer cuttings root best when taken after the first few hard frosts of fall when the plants are in dormancy. The dormancy factor is satisfied by cold temperature (35 degrees Fahrenheit down into freezing temperatures) for at least 6 weeks. I’ve had the highest successful percentage rooting when the conifer cuttings were taken from December through February.

When taking cuttings I like to use this season’s growth as it is easier and faster to root than old wood in most cases. Basically you are taking a tip cutting two-to-three inches in length. It is entirely possible to use the old wood or past season’s growth but the amount of time it takes to produce roots with these old wood cuttings is a bit longer.

Preparing the rooting chamber

A greenhouse is not necessary for successful propagation. I use large clear/opaque totes as my rooting chamber. Maintaining high humidity around the cutting is critical and I find totes work perfectly and are inexpensive. I fill the tote with a soiless medium of 1:1 peat moss and perlite to a depth of about 3” to 4”. If you choose to use something other than peat moss and perlite, make certain whatever medium you are using is sterilized. You will be leaving these conifer cuttings in this rooting chamber for a long time (ideally 12 months) and you do not want to introduce any pathogens which will result in mold, eventually killing your cuttings.

Once you have your soiless medium in the rooting chamber, you need to add enough water to the mix to make it damp, not soggy wet. Too much water and your cuttings will rot, too little water and your cuttings will dry out. I think one of the biggest keys to my success is that I use rainwater or pond water instead of tap water.

Preparing the cutting

I take my cutting, make a cut below a leaf and remove leaves from the bottom third of the cutting if possible (any foliage that would be in contact with the surface of the compost could rot) then at the end of the cutting stem snip the end at a very severe angle exposing as much of the cambium layer as possible.

I will then dip my entire cutting leaves and prepared stems into a rooting hormone and place them into a premade hole in the soilless medium in my tote. I always take a pencil and create a hole in the pre-moistened soiless medium, as I do not want to displace any of the rooting hormone. If you are into labeling your plants in your gardens don’t forget to label your cuttings. Trust me: if you put it off until later you will most likely forget the name.

I have used several different rooting hormones; Clonex, Rootech Cloning Gel, Olivia’s Cloning Rooting Hormone...However, I have had the most success with Dip n’ Grow and Dyna Gro K-L-N. If I use the gel I cannot dip the entire cutting piece in the rooting hormone. In addition, I never use the powder rooting hormones as I have never had much success with the powders.

Be careful with the rooting chemicals. I just dip the cuttings and place them in pre-moistened mix. Do not allow them to sit in the rooting chemicals as it will burn the tissue.

Putting it all together

Now that we have all our cuttings tucked nicely into our rooting chamber, with the lid fit tightly in place, we need bottom heat. The temperature of your medium is very important for callusing and root stimulation. I use heat mats and I also have a few waterbed heaters (Not sure if the electricians approve of waterbed heaters but they are inexpensive). Place your rooting chamber on these mats and heat to 70-72°F. Remember, we want Warm Feet and Cool Heads. I will leave my rooting chamber on these mats until March or April when the temperatures start increasing. I do have the rooting chamber in an eastern sun exposure in my house or in my greenhouse.

I peek into the containers to ensure things are looking good. I watch for mold and dry soil. I usually have to mist the plants/soil’s surface with fungicide laced water about once every other week and more often if I see any signs of mold or the soil is too dry. When I mist, I mist with rain water or pond water instead of tap water.

Aftercare

Once I take the rooting chamber off of the heat mats I move the totes under my benches in the greenhouse. For the past few years I have been stacking all my totes outside on the north side of the greenhouse or down in my basement and mostly forget about them, only peeking periodically to ensure they are not drying out, until November or December when things in my life slow down. That is when I will pot them up. I am finding the longer I keep them in the totes, the better root systems they have. Once they are off the heat mats it is best to keep them in a shaded area and out of direct sunlight.

Some of the plants take a bit longer to root and definitely need a full year or two to root. Once you begin experimenting with cuttings you will be able to tell. You will see with these slow rooters, that they will have a large bulbous bump and no roots or a slight start of a white thick root. When you see this, you will know this specific conifer needs more rooting time.

Please note: before re-using these totes (rooting chambers), wash them out very well with bleach water. This is imperative. I lost an entire batch of cuttings from using my totes over and over without cleaning them up with bleach.

I usually keep up-potting my conifer cuttings until I get them potted into gallon containers. At this point I will plant them out in my gardens.

Growing conifers from cuttings is a rewarding experience and seeing the fruits of your labor come to life makes this hobby all the more gratifying. You can also expand your varieties by trading your newly rooted plants with fellow conifer enthusiasts.

The article was written by Tangula Unruh. Reprinted from The Coniferite

Excerpt from Central Region quarterly newsletter. Gain access to archives of past newsletters and the National Conifer Quarterly by becoming a member of the American Conifer Society.

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