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Asexual Propagation
by John Harmon
July 28, 2002

I'm very happy that the weather turned to rain. Those hot muggy days at the beginning of the week were too much for me. It's supposed to be a dry cold here. It's sad to start thinking about fall but it's rapidly approaching and now is the time to take some cuttings to grow over the winter indoors.

Asexual propagation is a method of producing plants identical to the source. A fancy name for taking cuttings or vegetative propagation. Everyone that has taken a cutting from a Geranium and stuck it in a jar of water on the windowsill is practicing asexual propagation. There are more reliable methods than the jar of water even though rooting cuttings in water will work for some types of plants.

Geraniums are a good example. Choose an actively growing top shoot. Avoid taking cuttings from plants that are in the late stages of flowering. Young new shoots are best. Cut the stem cleanly with a sharp knife. Using pruning shears or scissors will crush the stem while it cuts and the bruised tissue has a tendency to rot in the water. I use a razor blade. Make the cut at an angle just below a leaf. Peal the leaves off the stem for a few inches. Stand the cutting up in a jar or other container with enough water to come up to the first leaves left on the stem. Leave at least three leaves. Place the cutting where it will get bright light but no direct sun. Cool white fluorescent lights encourage root growth.

You don't have to wait till there are masses of roots before potting up. As soon as roots appear the plant will be able to take up water and nutrients from the soil. Keep the new plant moist for the first few weeks and gradually more it into a sunny spot. Feed it with a starting fertilizer like Plant Start made by Green Cross. Starting fertilizers contain root stimulators to encourage rapid root growth.

You can skip the water phase altogether. Take the same cutting and coat the bottom inch of stem with a rooting hormone, powder or liquid, and plant directly into the soil. This works very well with softwood cuttings like Geranium. Rooting powders like Stim Root come in different types. No.1 and on up. Each kind is formulated for a different kind of cutting. Check the label to make sure the rooting powder is the right one for the cutting you are going to root. I like the liquid because it coats more evenly and can't "cake" in clumps on the stem, which can inhibit root growth at that spot. Use a very light dusting of rooting powder and shake off any excess. For rooting gel I like Clonex. It's a "precise and stable blend of high potency hormones, 500 times more powerful than most powders. Clonex also contains a complex profile of vitamins, mineral nutrients, trace elements, and anti-microbials, all in a gel base". Use a potting mix that will hold moisture to plant your cuttings. Follow the same directions for light and in a very short time the cutting will form new roots.

One thing to remember is not to dip the stem directly into the container of powder or gel. You run the risk of contamination. Shake the powder out or apply the gel with a q-tip to keep the rest clean.

There's some new stuff for starting cuttings called Gel-2-root. There is no need to water, feed or use rooting powder because the gel contains active ingredients to produce vigorous root formation. It also has all the nutrients a plant needs to enhance the growth of roots and the water to sustain the cutting while rooting. It comes in little tubs like yogurt and you just poke a hole in the cover and stick the cutting in. This stuff is also sterile so you won't have any problems with stems rotting because of bacteria or algae in the water. I haven't found a supplier in Canada but you can order from the website at: http://www.gel2root.com/ This stuff is pricey but worth the extra for tough to propagate species.

For plants with woody stems like Ivy or Silver Lace Vine It will help to enclose the potted cutting in a clear plastic bag to retain moisture. It takes a little longer for these kinds of stems to root and preventing water loss and stress is important to success. Put the new cutting under a cool white florescent light for a few weeks to get the roots started. Bottom heat will also help to encourage new root development. Use a propagation mat or the top of the water heater or any other warm spot. When new growth appears move the plant to brighter light and feed.

You can also use the same method to take cuttings from plants like Caragana or Lilacs for planting out next spring in the yard. They are not a touchy as some houseplants and can be started in potting soil after a dip in the rooting hormone and without the plastic bag. You will have to fool these plants into thinking it's not winter to keep them actively growing till spring. You can do this by giving them supplemental lighting. Provide 16 hours a day of florescent light on a timer till it's time to plant them out in the spring. I use cool white bulbs for starting and then switch them to full spectrum grow bulbs over the winter. Feed them a good balanced fertilizer or pot the up with some good compost. You can pack a surprising number of small plants under a four-foot twin bulb fixture.

A final thing to remember about bringing plants indoors is to be sure and check them for bugs. Any bugs you bring indoors will have to be dealt with later so leave them outside. Take cuttings only from healthy plants without bugs.



John Harmon owns and operates Tropicals North. Write to John at The Real Dirt, c\o 211 Wood St., Whitehorse, YT., Y1A 2E4 or e-mail tropnorth@polarcom.com.

 

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