Until the layer is full of roots, so you have what to cut off and plant. Trees can take a long time (mos)!

2 months. The new tree is now larger than the parrent!

Bill, my experience with layering is mostly with maples, but the findings may be applicable to calamondin. Initially I used the sphagnum moss and wrapper method but found the method rather cumbersome for any initial inspection. Some specie has a great ability to heal back a wound, in which case no roots will ever form and I believe your specie belongs there.
To make frequent inspection easy, I use rock wool and a drip system to maintain moisture and hold the wool with wire and clip. The drip system is sensitive to the weather: on hot sunny days, the drip interval is lenghtened and it stops whenever it rains. Another method is to use a split plastic cup (purchased from Lee Valley) and rooting soiless medium. The cup snaps into place and is easily opened to do inspection. With maples, it is often the case to wait more than a year for the roots to appear espcially with athropurpurum. The greatest problem is preserving the callus already formed through winter. It either dies sitting in an ice cube when frost hits after rain or gets scorched if the wool is completely dry and the winter sun gets too hot. It is too risky to continue with the drip system outdoor in winter. Your sphagnum method does not give this scorching problem but the ice cube is present. I guess your plant is indoor in winter, then you are lucky.
If you are impatient or want to speed up the rooting, you needn't wait for a full growth of roots. The plant knows how to balance its energy source between its various needs. I had the experience of removing a full moon maple branch which has a girth of 0.75" and when planted a height of 4 feet.It has only 2 rather small roots when I decided to spare it the winter hazzards and cut it. Then I kept the plant outdoor but close to a north wall, give its roots heat conveyed by running warm water at 75 deg. F through copper tubes. I wasn't sure that I could succeed at first but this plant did expand its reserved energy to grow a profuse rooting system, as other areas remained dormant in the cold. Naturally, the reserved energy drop did show up as lesser number of leaves at bud break. Never fear it recovered quickly enough and by summer you won't even notice any difference.

Actualy Layering the calamondin was extreamly easy. I did it with a tennis ball size of moss. I used cling wrap and wire to secure the ball, I made sure the area around the branch was sealed very good. After about a month I wanted to peek so I opened the ball and while digging in a little I could hear the roots breaking. Not knowing how many roots broak I let it sit another month. The moss ball was moist, not wet. This was in the spring time. So after 2 months, not watering the ball, I cut the layered branch and planted it. I did not have ANY die back and the layered branch is now larger than the parent. When it was planted It was growing new shoots and they contuined to grow. I think being in florida helped. The intense heat and sun probably made it quicker and a bit eaiser.

This next spring I may layer a few branches on both trees, I may try another method. Just so ya know, calamondins layer very eaisy in Florida as I demonstrated.

Thanks guys for the help.

Bill
You show such ingenuity when you used a tennis ball, wonder why nobody thought of that. Does your tennis ball allow rain to soak in as I am surprised that the moss is still wet after 2 months of florida sun?
In fact I just bought an rather expensive "styrax japonicum' but this one produces pink flowers. I am going to try your tennis version.
On another plant I am going to attempt to root some branches in autumn and through winter by supplying heated water through copper tubes. I wonder whether the warmth is sufficient to fight dormancy. Pity I can't get the buds to break to create the water needs of the branch in order to encourage rooting. Just curious on plant behaviour.

Jam, please read his post carefully. He says that he used used a tennis ball-sized piece or clump of moss, not an actual tennis ball. The "ball" of moss was then attached using cling-wrap.

-Audric

Well, true, I did not use a tennis ball. But after writing my posts and reading them I did think the same as jamkh. I dismissed it quickly. But why would that not work. I think together we came up with a good idea that needs explored.
Then only doubt is what is a tennis ball made of and are there any chemicals in the 'rubber' that would inhibit growth or cause harm?
Ill give that a try come spring and post back. Ill drill 2 holes slighly smaller than the thickness of the branch, for a better seal. Then cut the ball with a blade to open it up. Ill give it a try. Thanks jamkh for encourgaging the insite.

Bill,
A slip of the eye has perhaps given both of us an opportunity to satisfy our curiosity. Let's see if we both get the same response. Most interesting situation, I believe. THanks for mentioning the tennis ball.

UPDATE::
I tried to air layer a banyan tree, which should have been realy eaisy. The problem was with the equipment. I used a tennis ball inside of plastic wrap and aluminum foil. I used dip n grow on the cut/scrape. I think the chemicals in the tennis ball are toxic. I did not get any roots after one month during the wet growing season. With that, at the same time I air layered a calamondin again. I used plastic wrap, alum foil and dip n grow and I have a new tree with tons of roots.

Conclusion, dont use a tennis ball to enclose your moss on an air layer.

Thanks for the tip :-)! My very first layer was about 30 yrs ago and it was on a huge, out of control F. elastica in the lobby of a public bldg (part of the plant had grown 10' long against the sunny window!). I just used the prop-open stick & peat moss method (no idea if I had hormone then) plus plastic wrap. It worked(!) and I then just repotted the 4' long straggler into a new pot... wonder how it's doing now.