Striking Cycad Offsets
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Note: this is a series of postings to the cycad list group in June 1998 about striking cycad offsets or "pups".
First remove the soil from around the offsets. I wash the extra sand away with a hose to be able to see what I am doing. Cut all the leaves off of the offsets. This is important. Until there are roots on the offset, the leaves are drawing moisture out of the offset through respiration. This is the big secret to rooting E. woodii offsets. Many times people have told me their plant leafed, then died, they seem to leaf before they root, and the stem can't handle the stress yet, and this kills a very expensive offset. Cut the offset from the plant so that the cut is as smooth as possible. If it is not you can recut the offset smooth right before you process it. As soon as you cut it, dunk it in fungicide, for a few minutes. Pull the offset out and let dry.
When you are dunking it, if you want to mix in a liquid rooting hormone that is good too. After it is dry paint on a tree sealer, (that tar looking stuff). When I first started taking offsets, I found the larger the wound, the more chance of it dying. I would lose about 10%. After painting them, I rarely lose any. After the paint is dry, I put them in rough builders sand, about half down in the sand. Then put them in the shade, and don't water them. If it rains on them that is ok. If your irrigation hits them a little that is ok. You don't want the water to get into the wound if you have not sealed it properly. If you are in an area that does not get ant rain for a month then go ahead and water them once or twice a month. That should do it.
Hi folks - all that correspondence about rooting cycad suckets/offsets etc is interesting. But no-one has yet mentioned a little trick that we have found works wonders. We slice off (horizontally) the bottom quarter or one-third of the caudex very cleanly with a very sharp machete (very carefully!). This rather dramatic action exposes the ring of cambium, which is the tissue the roots originate from. After that, we let the cut suckers sun-dry for a few days and then plant in a very sandy well-draining mix. In an experiment comparing the success rate of the "cut" suckers vs. the uncut suckers (do I sound like a Jewish Rabbi now?) we found the cut ones gave 500% more roots and hence much more vigorous plants. Those of you who get the "Encephalartos" magazine will see our report + photos about this technique on pp. 9-10 of Issue #54 of Sept, 1997.
Roy, Actually most of the offsets I do are cut in the manner in which you talk about. I was told a long time ago not to pull the offsets off the parent plant. Sometimes if you pull the pup off a small pencil shape piece of stem stays attached to the offset. This makes a hole in the stem of the parent, and makes an entry point for fungus. So I always cut the offsets smooth from the parent. Usually this cut is fairly large. I have also found that the bigger the cut, the more roots you get. This big cut also gives you a better chance to kill the offset. That is when I started using the tree paint. This reduced the open wound to a minimum, but the roots grow right through the sealer, no problem.
Roy, have you ever tried to plant the back cuttings? If you take a big offset and cut the bottom inch or two off . Not only will you get a large plant, but a ring of small plants will grow all around the wafer looking slice. I have taken off a foot of trunk off a plant, rooted the top and the foot I sliced into three inch slices and started about 300 extra plants, all of course clones of the original (female) plant.
Regarding rooting offsets, my practice has changed over the years. I use to utilize bottom heat but presently prefer not to use it except for some more tropical central African species. Bottom heat does speed up rooting but also increases the chances of rot and loss. If you must root an offset quickly, bottom heat helps. However, by just rooting things in the greenhouse without bottom heat, I found my losses were cut in half. It takes longer but overall the results were better. I always, however, root inside the greenhouse.
A warm, shady outdoor location could be used. Our greenhouse gets to about 90 degrees in the summer and as cool as 40 degrees (F) in the winter. I utilize our tropical propagation house for Zamias. It gets down to about 55 degrees at the coldest and is more humid. I root offsets all year but would prefer to start the process in the Spring.
Encephalartos as a group are not difficult to root. A beginner could expect a loss rate of about 10 to 15%. In the best of hands, this can be diminished to 2 to 5%. Pre-soaking suckers with a fungicide such as Daconil is beneficial. I only utilize pumice as a medium although others use sand or perlite. I use root stimulants such as Rootone on the bottom of the caudix. I always check for soft or rotted spots and carefully disect them away prior to placing them in the rooting medium. Any cut surfaces are treated with fungicide and a sealing compound. I water about two to three times a week, preferably around the caudix and not into it's crown. I wouldn't even think of checking for roots until at least three months because of the risk of breaking new brittle roots. A safe thing is to wait until you see roots at the bottom of the container. With any luck, you'll have a rooted and leafed out specimen in 6 to 12 months. Seeing a quick throw of leaves with no existing (or formed) roots is often an ominous sign. Collapse and death often follows on many species. I prefer the offset to root first and months later throw it's new leaves.
Of the Encephalartos, there are certainly easier species to root than others. Blue species such as E. horridus and E. lehmanii are very satisfying, E. longefolius and E. arenarius are a little more tricky. E. cycadifolius and E. ghellinckii are definitely more troublesome. E. latifrons and E. woodii are quite difficult. I would recommend that, due to the expense of the offsets, one not purchase a E. latifrons or E. woodii unless they are fully established. Dioons and Zamias root well, but Zamias prefer a little more humidity. Ceratozamia suckers are the slow and fairly difficult to re-establish. They can take years.
As you are aware, we have established many thousands of suckers of almost all species and have learned through our mistakes and failures. I would recommend that an eager person on the list give it a try and follow the guidelines above. The rewards are very satisfying.