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It’s been many years since I’ve had a chance to write on air-layering
by Art Drysdale
by Art Drysdale

email: art@artdrysdale.com

Art Drysdale, a life-long resident of Toronto and a horticulturist well known all across Canada, is now a resident of Parksville, British Columbia on Vancouver Island, just north of Nanaimo. He has reno-vated an old home and has a new garden there. His radio gardening vignettes are heard in south-western Ontario over radio station Easy 101 FM out of Tillsonburg at 2 PM weekdays.

Art also has his own website at http://www.artdrysdale.com


September 9, 2018

Above, David’s Dumb Cane plant as it is now. Below, one air-layer showing the plastic enclosing the sphagnum moss; and four air-layers on one plant at the same time. Photos courtesy www.instructables.com/id/ .





 


 



 

Recently I had a short letter from an old Toronto friend David Jaakkola: “I have a question about an indoor plant which was given to me when it was about 2 ft. tall and now years later it is over 7 ft. I don’t know what type of plant it is (see picture) and I’m wondering what is the best way to cut off the top without killing it. Also for the part I take off can I repot it to grow or will it be dead? Any advice would be appreciated.”

The plant you have is a Dumb Cane (botanical name: Diefenbachia picta).

There are a number of ways it could be handled but probably the easiest would be to use a treatment known as ‘Air-Layering’, which is quite easy to do and is usually successful. You only need a good sharp knife, a match stick or thick toothpick, a handful or two of sphagnum peat moss (not regular peat moss) which is available in small to large packages at virtually any garden centre, and a piece of clear plastic such as you might cut out of a small bag, and finally a couple of twistems or thin, tough string.

If you go to a garden centre to get the sphagnum moss, ask them if they have a little tin of rooting hormone such as one called Stim-Root. There has been a shakeup in that market and I don’t really know what is available now.

What do you do with all of this? First, with the sharp knife (such as an Xacto) cut a wedge shaped segment out of the stem where you wish the new roots to form. This should be done just below a node (place where leaves emerge). The cut segment should go at least 1/3 to ½ of the way through the stem. The little wedge piece is garbage. You should then place a short piece of the wooden match stick in the wedge-shaped hole on the stem.

Then, if you managed to get some Stim-Root (or equivalent) smear a thin coating of the powder on both exposed edges of the wedge-shaped section. You might want to do the smearing before inserting the little piece of match stick.

Then cut your piece of plastic in a square or rectangle (about 30 cm) and keep it handy. Wet the sphagnum moss with tap water and squeeze it out so it does not drip. Apply the sphagnum moss over the cut stem for a length of about 10 cm (four inches), squeezing the sphagnum moss so it stays in place and then wrap that whole little bundle with the cut plastic, tying it at top and bottom with the heavy string or Twistems.

Set the whole plant so it does not get much sun or the leaves will burn, and in a couple of weeks you should be able to see some tiny roots growing within the sphagnum moss. Once the new roots appear to fill the plastic surrounding the sphagnum moss it will be time to cut the main stem of the plant totally, thus removing the newly rooted (air-layered) plant. Depending on where on the plant’s main stem you did the air-layer, you may be able to keep the old original plant going, or if there are no leaves left, you might just need to throw the old plant out, perhaps on a compost pile.

Take some fresh potting soil and a new (?) pot and plant the air-layered top of the old plant in it and keep it shaded for several weeks. Be sure to remove most or all of the sphagnum moss from the new roots before you plant the new plant. It should grow well.

If a month or more passes and there are no signs of new roots having formed, that usually means the air-layer has not worked, and you will have to try it again, a little further up the main stem. By the way, your plant actually looks multi-stemmed which actually means that you could try doing more than one air-layer at the same time.

I don’t think I mentioned at the outset that Dumb Cane is a poisonous plant so it is wise not to bite into any part of it, and to keep pets and babies away from the plant at any time.

I suggest that you check the WWW for ‘air-layering’; or you may find that the following site is all you need: https://www.instructables.com/id/ .

   

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