Citrus trees sold as ornamentals/houseplants in 1-gal pots are typically small-leafed with correspondingly thin branches, looking much like small bushes. Given the proper conditions they grow to much greater size and bear little resemblance to their original form. (Not surprising since they are trees.) So could it be that these ornamentals are treated with a growth inhibitor to maintain their small size? It occurred to me that this may be a possibility since poinsettias are so treated to make them short and bushy.

[Question cross-posted to another forum.]

Hi Junglekeeper, you pose an interesting question. I guess, anything is possible, but it would be illegal. If a growth restricting chemical such as B-9, and others, were applied as a spray to a small citrus tree, they would of course, greatly reduce the tree's growth, through the reduction of the internode length. I have sold such chemicals to the floral industry, for years. However, citrus nurseries would not spray these type of chemicals on citrus for several reasons. First, the tree produces eatable fruit, and secondly, in most countries (United States and Canada included) it is illegal to use a chemical for any application that is not SPECIFICALLY listed on the product label. In the case of citrus, the tree is not listed on the product label, therefore, the application would be strictly illegal, with serious EPA consequences. Happy New Year. - Millet

The small (usually #1 pots) containing citrus with fruit are most often calamondin. Often referred to as "miniture oranges" they are grown from rooted cuttings and pinched or pruned several times to cause them to form a small bush. Given the right conditions, calamondins will bloom and fruit as soon as they get a foot or so high. Because of this, they are profitable for growers and retail nurseries as impulse purchases. The small size is deceptive - they can easily grow to 25' or more.

There are some on my neighbor's property, that are at least 25', that were grown as seedlings. They are loaded with fruit and make beautiful ornamentals. I will try to remember to take a picture tomorrow and post it.

Millet is right. Citrus nurseries are strictly monitored to ensure that they are using only approved fungicides and insecticides. I know of no growth regulators that are approved for such use. I am sure they can and do use pruning, fertilization, and moisture and light levels, in achieving desired growth responses.

Ned

I've seen Calamondins sold as Ornamental Citrus also. It used
to be somewhat more likely to see them offered for sale by mail
order seed and plant sources they got in, as many of those olden
day mail order sources did not grow their own plants, for small
growing Citrus mostly as an indoor novelty plant.

Some of the novelty Citrus sold here that I can recall have been
the Myrtle Leaf or Chinotto Sour Orange that were sold in one
gallons. I have not seen them in a while and of course as soon
as I write that I'll see some rather soon.

I agree with Ned in that from what I've seen also that these are
seedling grown or rooted cuttings that have been pinched back
to keep them small in size. It is their natural dense growth habit,
appearance and hands on training is what makes them the novelty
ornamental plant. As soon as they are bumped up to a larger sized
container they will outgrow their current state shape. At one time,
the Calamondins and the Myrtle Leaf Citrus made for very nice
pre-Bonsai plant starting material.

Jim

Thanks for the replies. I was not aware of the restrictions on the use of these chemicals. I thought of the possibility of their withholding fertilizer to a minimum required to maintain healthy growth. However most trees seem to come with a liberal dose of slow-release, osmocote-type of fertilizer. I can't say whether it was thoroughly mixed into the soil so perhaps it's sprinkled on top just prior to being shipped out from the growers.

Ned wrote:

I am sure they can and do use pruning, fertilization, and moisture and light levels, in achieving desired growth responses.

This is the most likely explanation then. A trade secret, no doubt.

My calamondin produces new growth that is in proportion to the old; it has not increased much in size from when it was purchased. My Eureka and Lisbon lemons, which receive the same treatment, are a different story. Their leaves and stems are easily 2-3 times the size of the old. (The larger leaves are 7" long and 3.5" wide!) One stem in each of these two former bushes has become dominant and both are now over 6' tall. I know these two varieties produce relatively bigger trees but the differential is eye opening. From what I can tell all my trees that came in #1 pots are cutting grown and so their size is not influenced by a rootstock.

Now that I think about the differences between these trees, maybe forced blooming is a way to control their growth. The calamondin has bloomed and produced a large number of fruit whereas the other two have produced much much less in comparison. This would appear to be a good approach for the growers to take since not only would it control size but a tree with flowers and fruit would be much more desirable as an ornamental.

A trade secret, no doubt.

I think a photo of the particular ornamental Citrus in question
may promote more ideas as to what really went on to produce
the plant in question. We are not so sure any of us can say
or conclude with certainty what may be thought of as being or
is a nursery trade secret when dealing with such an unknown.
If we have a specific plant to reference and the grower source
is known to us then we can ask them how did they do it. The
answer coming from them will have much more meaning than
a possible, even a probable answer will have coming from us
if we have not seen an example or have done it ourselves. We
deal with the growing source in such cases.

Each nursery that is producing such plants may have their
own way of doing things such as producing the plant for sale
that may have a dense, compact shape with small twiggy
branches than some of these same or similar small trees
seen in retail outlets loaded with fruit as well. Our seeing
the small plant covered with small fruit does indeed require
a little different means to get the plant to that point. It is not
so much a trade secret for the grower to tell people how to
achieve the small tree covered with fruit, it is just that they
may choose to be more selective in who they will tell how
they could accomplish this feat. From a grower standpoint,
what they may have learned on their our own and from others
can be information they may not want to give out just to anyone
online and herein might be the so-called trade secret to someone
not directly involved in the nursery trade.

Jim

Stressing the plant by witholding water will do the trick, but this is seldon necessay with calamondin.

Before we get carried away I should say my comment on it being a trade secret was tongue in cheek. I'm sure there are techniques but I wouldn't go as far as to suggest they're trade secrets applicable only to citrus. Having said that if anyone is privy to such information I'd like to hear from you.

In any case both lemons came from Monrovia. If I had a proper camera I'd take some photos. The trees remind me of Jack and the Beanstalk. Is the leaf size unusual for these two varieties of lemons? Lemon leaves are supposed to be 2.5 - 4.5" long according to Julia Morton's write-up on the lemon. Mine are quite a bit longer.

Sorry for the intrusion, I thought the original question was wanting
to know a chemical means that can cause a Citrus plant to dwarf
down in size, my mistake.

Jim

An apology is not called for, Jim. I'm interested in ANY (non-toxic) means to control the growth of these trees. Besides, your feedback is always welcomed. I think this is a case where a winking smiley after my comment would have been appropriate. Do you have any ideas on the seemingly oversized leaves? Maybe I'm being too generous with the fertilizer? The trees appear to be very happy.

Growers must have something at their disposal to force branching. I recently saw some variegated calamondins that looked nothing like Laaz's seen in this thread. The scion on each shrub looked similar to a witch's broom, with many, many, long, weak, spaghetti-sized branches many of which had fruit at the end which caused them to bend over resulting in a fountain effect. Leaves were few and small-sized. These do not look like normal, healthy trees; they looked weak and spindly. I guess they're somebody's idea of 'ornamental'.