It is a huge selling advantage if a nursery can sell flowering or fruiting citrus, compared to their non-fruiting equivilent. How do they induce flowering? Is it chemically, or a drought stress?

I'd like to induce flowering and fruiting in some of my citrus grafts in bags that I plan to give to friends.

Thanks,
John

One of he fasted methods is by grafting a mature bud, onto a root stock. After grafting the plant should flower in 1-2 years. You can speed growth by maintaining the roots at approx 80F while artificially lighting the tree to extend the "daylight" to 15 hours per day. Doing so should produce 5 flushes of new growth per year. -Millet

Millet, I do the grafting already. I'm asking specifically on how to induce flowering as the commercial nurseries appear to be doing. Do you think it's an artificial daylight extension? My thinking is that it's a foliar spray(?)

There are hormones, which induce flowers, but I have no idea if they are used ...

Chemical retardants interfering with gibberellin production are used to shorten juvenile phase and to induce out of season flowering.
Below are some links to the action of one of them - paclobutrazol.

http://www.jhortscib.org/Vol69/69_1/21.htm

http://www.fshs.org/Proceedings/Password%20Protected/1995%20Vol.%20108/361-364%20%28URRUTIA%29.pdf

http://nepjol.info/index.php/JIAAS/article/view/661

This is a very interesting question, as I bought a couple of young grafted liner trees (very young, first year) from Citrus Tree Source. I re-potted them, and when I was watering my Buddha's Hand (not kidding), I noticed it was blooming. I was pretty shocked, especially this particular cultivar, which can be hard to bloom and fruit for some folks. Now, the Lee x Nova is just being a young tree, no blooms, and growing slowly. I don't know if this is just the fact that I'm in a climate that is very conducive to lemons, or if Citrus Tree Source treats their young seedlings to promote early blossoms. I have a call into them, and I can ask what they do, if anything. It could be how they fertilize, but frankly, most commercial tree growers growing trees for dooryard orchard culture tend to fertilizer with straight nitrogen or a very high N fertilizer to promote dark green, leafy growth. Curious question.

From my experience a period of cool weather will start the lemons / citrons blooming.

Ah, well then. Just like my limes. We finally had a break in our hot, hot weather about 2 weeks ago. Both my Bearrs and Thornless Mexican limes are blooming/have bloomed. I'll have to go check my Mystery lemon tree more closely, and my Meyer. My Palestine lime seems to be much like my Meyer - constantly in a full cycle of everything. All those beautiful, insipid fruits I just toss. I need to call Millet and have him come over and take care of things. I just am too much of a softie, I guess.

In my experience, rooted cuts/air layers bloom much sooner than grafts.

Drought will pop most citrus into immediate bloom. Don't dry them enough to drop all the leaves off, but do let them wilt. Most will then flower on the next flush of growth. Once flowering has been induced, you need to go back to providing a good, steady water supply so they'll set fruit rather than drop all the flowers off. The drought stress is just to initiate the formation of flower buds.

Verdelli Method of Sicily

Same can be done in pots, but very carefully.

In pots all is happening much faster and the leaves should only wilt a bit ...