First, allow me to indroduce myself. I am a 32yr old male attorney from Brooklyn, NY- originally from the UK.

I am completely and hopelessly addicted to gardening, particularly fruit gardening, particulalrly tropical/mediteranean fruit fruits.

I have a postage stamp sized back yard (about 20ftx 10ft) but I manage to cram in about 30-40 fruits and berries.

I recently bought a 800 wsuper spectrum lighting system and currently have a 30 plants crammed into a small room (4ftx4ft) in the basement, including a meyer lemon, a golden nugget mandarine, another mandarine of uf unknown variety (i lost the tag), etrog, and washington navel orange. (see pics below.)

The temp in the room ranges between 75-85 during the day and 50-65 during the evening. I have a small humidifier in the room and the gage reads the humidity as between 15 to 40%- normally around 24%, although the gage is as far away from the humidifier as it can be)

I plan on moving my plants into my garage next winter as the garage is a larger space- I will have to insulate and heat the garage.

ok here is my q- will the citrus benefit from misting by one of those hand held misting spray bottles. if yes, how often should I mist

link to pics
http://s189.photobucket.com/albums/z285/lycheeluva/jan%2008/

IMHO there is not much to be gained by misting except cooling when the leaves are in direct sun. If you really just want to raise humidity there are better ways. Repeated misting can be detrimental if your water has too many dissolved solids.

Welcome to the forum.

what are the better ways to add humidity (other than by adding humidity machines)?

Welcome to the Citrus Growers web site. We are excitred to have you as a member. Many indoor growers of citrus, frequently hand mist their trees, believing that their efforts are providing a needed benefit to the tree. Test by the University of Purdue showed that the process of hand misting provides very little, if any value, due to the extremely short life span of this type of mist. The University's report did state that a minor benefit could possibly result as an aid in reducing the dust residue that collects on the leaf blade. If anyone is interested in the report, they can find it on the Purdue web site. From reading your posting, I gather the actual humidity level at the spot where the trees are located is not accurately known. Humidity levels approximating 70 percent would be optimum for a citrus tree. - Millet

Thanks Millet.

Do you or anyone else have any suggestions what I can do add humidity. I plan on buying a proper humidity machine once I move my plants into the garage next winter. But is there anything I can do without a humidity machine to add humidity for the remaining months of this winter.

Placing a shallow tray with gravel and water in the area will help more than misting.

Millet and I live Colorado which is a very dry climate. I add very little extra humidity and my plants appear to not suffer any problems. Any problems are caused by me and not the climate they live in.

You have to understand that loading moisture into the air lowers the air temperature unless you supplement heat energy in evaporating the water.

Real field observations of citruses in the semi-arid farms of California and Arizona that produces very appealing citrus fruits is a big paradox that indeed it would take a lot of convincing for me that an optimum humidity of 70% is the best for producing the best citrus fruits. Our summer humidity averages far less than that and California produces most of the cleanest exportable citrus fruits. I am convinced that in the "inland empire" of California has the best citrus quality, both taste and appeal in the world, having gone, seen and tasted fruits there myself. Yet the average humidity is less than half of the supposedly optimum 70% RH.

I agree with you Joe-- living down here in the humid south, all we get is problems from the extra humidity-- fungus, molds, and disease thrive in a humid environment.

It is recognized that the fruits of all citrus varieties tend to be smoother, thinner skinned, and in general more juicy and perhaps richer in quality when grown in an atmosphere of fairly high humidity. It is a common observation that fruits of the Washington Navel and the Valencia orange grown near the coast in California tend to be more nearly spherical. It is an environmental response due at least in part to the difference in atmospheric humidity. One of the most marked effects caused primarily by differences in atmospheric humidity to be found in citrus is in connection with the sever fruit drop, know as "June Drop" that occurs commonly in warm dry areas. In the desert and semi-desert sections of California and Arizona this drop is so heavy many years, that the yield is greatly reduced.

Average Humidities:
Los Angeles 63%
San Diego 72%
Riverside 52%
Fresmo 52%
Corpus Christi 74%
San Antonio 63%
Miami 73%
Jupiter 81%
Moscow Russia Unknown

One problem concerned with the growing of citrus in humid areas, as already stated by Skeet is the higher levels of fungal diseases and insects.

Millet

Are the average humidities quoted based on yearly averages or growing season averages? Were those humidities taken from an Airport Station or from Agrometeorological field stations?

We have measured (using Polycorders and portable weather stations) humidity hourly during the growing season during my graduate studies, and the humidity ranged from 15% (around 5PM DST) and 80% (around sunrise). The average during the growing season would be around 30% in most places where we measured them. If you factor in the winter NON-GROWING season, it skews the annual humidity up as the humidity is hovering above 80% for about three months when the citruses are almost doing nothing in terms of growth, except for the ripening and deeper development of colors of fruits of cultivars normally harvested at those time.

I believe that the June Drop is not mainly caused by humidity, but rather, it is only CORRELATED with it, not cause and effect. My main suspect would be untimely application of water during the drier years, when there is not enough water stored in the soil during those years, and farmers doing the same schedule and amount of application. This will lead to inadequate water for the citrus crops, and so the citruses will respond by dropping more fruits in those drier years. And drier years have lower humidity and are therefore correlated with the June Fruit drop but not the cause. For farmers that knew better on how to deal with the drier years, it is the amount of watering and the timing that is crucial for minimizing yield losses, more so, than increasing the humidity of the air.

If there are scientific studies in a controlled environment where adequate water is supplied, and all the other factors equal except for humidity which will be varied and the yield compared, then it should be a more convincing cause and effect studies. I'd be glad to read such scientific literature.

Joe, June Drop, is a major problem in the citrus industry. I'm sure that a person can find an almost inexhaustible amount of information concerning its cause and effects. For starters begin with the Citrus Industry. Everything you say above I'm sure would be generally helpful in the cultivation of citrus in any major citrus growing region around the world, whether that region's climate is hot, warm or rather cool. What you stated in your post is not only good citrus culture, but also good culture for almost any type of crop grown by farmers world wide. I believe that there is much more to June Drop than simply correlations. Thanks for the response, it's appreciated, it always makes for better and deeper discussion. - Millet

I guess handmisting is not benefical.
The humidity lasts not long enough, to realy reduce air aridity and lessen the higher evaporation from the leaf blade.
Usually the fine droplets also wetten the leaf surface and can be a benefit for fugal spore growth, and thus provide better conditions for fungal attacks.

There for: I encounter not realy problems in low humitidy, if I maintain a good water supply to the pot, and maintain good water condition to the roots... and my humidity drops well below 24% rH during heating phases....