One of the primary means of propagation for cycad growers and collectors is pup, or offset, removal. If you are not yet a cycad enthusiast, it is analogous to taking cuttings from other plants. Pups are genetic clones of their parent plant, and they typically develop around the parent plant near of just below the soil level. This article is intended to explain procedures related to successful pup regeneration.
I try to remove most of my pups in late winter to early spring (March to April). This allows six to seven months to regenerate roots and push leaves before the temperatures begin to dip in fall.
The first thing that I look for is the size of the pup or pups to be removed. I prefer to remove pups only when they have reached the very minimum size of about 3” diameter, but I am more comfortable with a 4½” - 5” diameter pup if given the choice. I do know that pups can be successfully grown if removed when much smaller, but a larger pup has the advantage of greater caudex mass, which translates to greater food reserves. This enables the regeneration of roots and leaves more readily and with greater performance. Since pups generally grow more rapidly while they are still attached to the parent plant, we shouldn’t hasten their removal if the caudex mass isn’t sufficient. Another advantage to larger pup size is that as a pup develops in size while still attached to the parent plant, that pup begins to develop its own root system, and gradually takes over some of the burden of sustenance that had initially been solely provided by the parent plant and its root system.
Complete/Partial leaf removal on pup:
Typically when pups are removed, some or all of the leaves on the pups are also removed. Pup leaf removal serves two purposes. First, when the lower/older leaves are removed from the pup, this provides easier access to the separation seam between the parent plant and the pup. Second, a pup that has had some or all of the leaves removed is less likely to dehydrate during the reestablishment process, and the food storage that is in the pup can then be dedicated to new leaf and root production. If a pup appears to be significantly robust and is holding a lot of leaves, I will often try to preserve about 20% - 30% of its leaf mass. This involves completely removing many of the older leaves (the ones closer to the ground) and cutting the remaining newer leaves so as to preserve about 1/3 of their overall length. This step is contingent on being able to preserve a small portion of cleanly cut root mass when the pup is removed from the parent plant. If in fact I am able to maintain some healthy leaf and root mass on the pup at the time of its removal, then the pup can carry on with the normal process of photosynthesis and hydration, or water intake, even though these systems aren’t at their full capacity. The key to this process is to try to maintain a relative balance between roots and leaves. If you have misjudged, and the amount of leaf mass is excessive, the transplanted pup will often reject or abort some of the partially cut leaves, because it cannot sustain and maintain full hydration with the smaller diminished root system. In this case, cut off more leaves so as to relieve some stress and correct the imbalance. After cutting and reducing the leaf mass on a pup, if the pup cannot be removed with sufficient healthy roots, then I would completely cut off all of the remaining partially cut leaves and proceed with the normal process of re-rooting and flushing a cleanly trimmed leafless pup.
The process of removing a pup begins with digging with a shovel and hand trowel and any of a myriad of other tools, to expose as much as possible of the entire pup and the uppermost roots where they emerge from the pup without damaging too many roots. It is not unusual to target one or two pups for removal prior to digging, only to remove the soil surrounding them and find several other pups that weren’t visible and may be a better choice for removal, or finding that you are better off removing more pups than you had intended to remove, in order to access your original selection. Be flexible. After removing as much soil as is needed, I will often use a hose with moderate water pressure to wash away most of the remaining soil to gain a better picture of the pup attachment and all roots in the general area.
Finally the harvest! I prefer to use a sharp wood chisel with a 2” wide blade along with a hard rubber mallet and a variety of gently tapering hardwood wedges that range in length from 6” to 14”. With the rubber mallet, drive the chisel down the seam between the parent plant and the pup to cut through and separate the tissue that joins the parent plant and the pup. I try to get as clean a cut as possible midway between the parent plant and the pup. At this stage, if no other pups are hindering removal, then all that could be preventing pup removal would be pup roots. Ultimately you will need to cut some roots, but at this point, you should try to save as much root material as possible. Try to make your cuts as clean as possible. A cleanly cut root, even if only a few inches long, is more likely to regenerate than a shattered or raggedly torn root. When all the pup roots have been cut, with a little coaxing the pup will come free.
Treatment of wounds:
At this point I get the hose out and spray water onto all wounds on the parent plant and pup, including the cut roots. While still damp, with a paintbrush, I dust a fungicide powder onto all wounds on both pup and parent plant. Some growers recommend adding rooting hormone to the root wounds on the pup along with, or in lieu of, the fungicide, in order to stimulate robust root growth. Then I put the pup in a cool dry area (garage) for one to two weeks, and wait for the wound on the pup to dry out and callous over. I will leave the parent plant with its treated wound exposed to the air for about the same amount of time before once again covering the dried wound with soil up to its original soil level.
Step 1 – Planting in Pumice:
When the time comes for planting the pups, I prefer to use a sterile inert potting medium, such as pumice. Other rooting mediums such as sponge rock, lava pebbles, perlite, etc. may be used. I find pumice is uniquely suited for rooting out pups, because it has the unique propensity to hold the right amount of moisture for pup regeneration. Pumice is a porous volcanic medium that is available in several graded sizes, and I prefer a grade size that is between ¼ and ½ inch. Use this pumice to surround and secure the pup in a plastic grow pot while new roots and leaves regenerate. The pumice can cover the pup and roots up to approximately 2/3 of the height of the caudex (bulb), as well as the entire root callous below. Approximately the top 1/3 portion of the pup should remain free of pumice, or uncovered. This growth bud for new leaves is best kept dry. Be certain that your grow pot has sufficient depth as to allow room for the pup’s new root development that will soon follow. This area should be a minimum of two times the height of the pup for root growth. As was mentioned earlier, the pumice is sterile and inert, and will supply no nourishment to the pup as it develops. As the pup begins to produce roots and leaves, usually within a few months, you may wish to begin using a water-soluble chemical fertilizer at about ½ of the recommended strength with your weekly watering regimen. This can assist in more rapid growth of your pup, and take some of the burden off of the pup’s own food reserves that are being depleted for root and foliage production. Even though your grow pot with pup and pumice will hold very little of the water or water-soluble fertilizer that you provide, you only need to drench the pumice and rooting pup about once a week.
Step 2 – Placement of potted pup:
Your rooting pup will benefit from warmth as it regenerates. A greenhouse is an ideal situation. If a greenhouse is not available, provide a warm location and moderate light. A good daytime temperature range for a rooting pup is approximately 75-90 degrees Fahrenheit.
Step 3 – Checking for roots:
When the pup has finally produced a flush of hardened leaves, it is necessary to carefully ease the pup from the grow pot to inspect the root production. If you have little or no root regeneration, then you should replant the pup in the pumice and check again in a few months. If you have a reasonable amount of new roots, then the pup should be completely removed and gently shaken to remove most of the pumice. The low water pressure spray from a hose can also be useful to carefully spray pumice from the roots. USE EXTREME CARE AT THIS STAGE, BECAUSE THE NEW ROOTS ARE VERY BRITTLE. It isn’t important to remove every pumice particle.
Step 4 – Planting in Sandy Loam:
Next, the pup should be potted up into a slightly larger grow pot and surrounded with a well-draining sandy loam. This potting mix will allow the roots to develop further and gain strength in a more natural soil medium. Generally speaking the rooted pup should be covered with potting mix up to approximately midway up the height of the pup. Some growers may choose to plant a pup in the ground directly from the pumice medium. Although this can be done successfully, I prefer the added time of growing the pup in a grow pot with a sandy loam soil mix outdoors. When the pup has produced the second flush of leaves, it has proven the efficiency of its newly developed root system. After the second flush has hardened off, your new plant can safely be planted in the ground.
The techniques described here are not the only techniques that can be successfully employed. These are just a few of the procedures that have worked well for me, and it is my hope that they will also work well for you.
Grow and prosper,