My aim with my original write up regarding twin scaling, was to try and provide a simple, helpful guide that would achieve consistent results. Over the last couple of years I have received various helpful comments from people who have been twin scaling for longer than I have, so I have begun to experiment a little more.
Not wanting to complicate matters too much, I have retained my original write up, now entitled “twin scaling part 1”, with only a few minor amendments, and have added my other findings in this write up, entitled “twin scaling part 2”. It may be useful if both are read before you embark on twin scaling yourself.
1. Personally, I prefer to use a bulb that has undergone the complete growing cycle un-checked, whereas some will use a bulb that they have obtained earlier on in the season, either potted up or by mail order. There is no problem with using a recently acquired bulb, it is just that I have found that due to the interrupted growth cycle, there is a check in the growth of the plant, so you can end up with a smaller bulb. It is always a difficult decision whether to chip now or risk losing the bulb during the coming winter.
2. In twin scaling part 1 I mention cutting off the neck and up until recently I have discarded it. After various consultations I decided in 2008 to experiment in using the neck as well. 25 bulbs were chosen, all a different variety and the neck rings were included with the chips during the incubation period. Out of these 25, 9 varieties produced tiny “pips” on the neck rings. At this point the blind neck rings as well as the blind chips were discarded.
Neck rings after incubation period, showing the ‘pips’ that have formed.
Photo courtesy of Dr. Dowling Munro.
The neck rings that had produced “pips” were potted up separately to see whether they would produce bulbs. Out of the 9 varieties, 8 produced small bulbs, albeit in small numbers ranging from 1 to 5.
Bulb produced from the neck ring
Comparison in size between bulbs produced on the neck and bulbs produced on the basal plate (Ballerina).
The neck bulbs were again grown on separately to see whether they will eventually reach maturity and to ascertain their likeness to their fellow bulbs.
This experiment has continued in 2009, with a total of 74 varieties used, out of which 28 varieties produced “pips”
3. Having a somewhat impatient nature, I usually allow the incubating chips 12 to 14 weeks in the vermiculite before I become eager to pot them up. Any chips that have produced the tiniest of bulbils, I have usually discarded. Sometimes patience can be a virtue and as long as the vermiculite is still moist, any chips that have produced the tiniest of bulbils can be left for a few weeks longer. You may find that the bulbils will eventually grow. After 20 weeks I would either discard or pot up regardless.
4. I have always discarded “blind” chips, by which I mean any chip that has not produced a bulbil between the scales on the basal plate, or in the case of necks, any “pips”. In 2009 I began an experiment to see whether blind chips or necks, if potted up as normal after the incubation period, would indeed produce bulbils. Out of 38 varieties chosen, 10 varieties had some blind chips and 19 had blind necks. All of these have been potted up separately and I await the outcome. Unlike the pots of bulbils that produce growth and are then allowed to dry out during the summer, the pots containing the “blind” chips will need to be kept moist, otherwise the chips/neck rings will desiccate in the dry compost.
I will update my findings next year (2011) and I hope that this information has been of some help to you.
Now in 2012 I can say that...
a) It would appear that plants produced from the pips of the neck are identical to those produced from bulbils off the basal plate.
b) As to ‘blind chips’ and ‘blind necks’, I have personally not found any evidence that they will eventually produce bulbils/pips, so I now discard them.