People ask about defoliating citrus over and over, if you search GW you will probably find multiple existing discussions - I wouldn't assume that your location makes comments originating in warm climates or in reference to indoor specimens irrelevant. All the more so since you are talking about defoliation occurring during the warmer time of the year.

Thank you for the feedback! I posted here specifically for a couple of reasons:

1) I've not been able to find an answer that works for me on the Citrus forum. One of my plants is in their recommended mix, I water with their recommended fertilizer and with added vinegar at about the average recommended frequency, and I've read a great many posts there.

2. There are a number of very experienced folks in the NW forum (yourself and Gardengal come to mind). If, for example, I should be taking my plants inside at night to keep them from going dormant (roughly believed to occur at around 55F) then I'm more likely to hear that from someone that is already growing citrus in our cool climate than I am from someone in southern California.

3. I'd like to get a pulse on how often NW gardeners are watering their plants, and what potting media they are in, to evaluate my own frequency.

Thanks again!

It sounds to me like you are fiddling with them too much and maybe even producing a problem in the process. Watering with vinegar for instance, why do that? To make the rooting environment more acidic? Usually here an acidic condition in excess of what is desired may rather often occur, even for plants like rhododendrons.

In general when plants of any kind drop leaves to excess or at the wrong time of year there is something haywire with the rooting environment. Of course, other things happen also, such as sun burn or frost damage.

Pictures please. I had horticulture classes and worked in a nursery in Phoenix AZ in my youth..sold tons of citrus and have grown lemons in my greenhouse here in Portland ...No idea why you would be watering with vinegar...

Iron chlorosis is frequently associated with alkaline soils such as they have in the desert SW - where irrigation water may often also be full of minerals. Here I would expect leached out, soil-less container media to be acidic. Countering this tendency is probably why dolomite chips are often included in such preparations, here and elsewhere.

If you have in fact been trying to acidify your container media you should probably get a pH test kit and see where you are.

I grow Meyer lemon, Washington navel, and a key lime (from seed). I would stop using the vinegar, and just use the foliage Pro. Meyers are heavy feeders and I use 1.5 tbs per gallon and the other trees I use 1 tbs of FP/gallon. I also use a slow release fert during the summer. My orange tree is in a 511 the other two in gritty. I bring the key lime in the house for the winter but the other two trees I leave out side almost all winter. Last winter I brought the trees inside for the night maybe five times. Most of the time they were kept under a patio to keep them dry. In summer I water everyday if the temps are 90 or above and every other day if the temps are in the 80s. Good growing, Jack

Thanks for your feedback. Here are some pictures:

I poked around in the roots this morning and it didn't seem like the roots had developed much at all since being planted - they were confined more or less to the original diameter of the root ball when the plants were planted. I found some dry and crumbly roots in the lemon's pot - does this indicate past root rot? I did not find any brown / slimy / smelly roots.

How often would you imagine these plants might want water when daytime temps are in the 60s and 70s?

I think a soil test is a great idea - I'll get a kit this weekend.

One doesn't typically "test" a potting or container soil, primarily because such a mix generally contains no soil (they are 'soil-less' mixes) at all and all nutrients are supplied by the grower in the form of a liquid fertilizer. You will not get any sort of accurate reading (and even less so when using a home test kit!!). Generally pH is less of a concern as well with any sort of container culture as that too is addressed by the grower, either through an acidic based fert or through applications of either lime or sulfur depending on which way you need to adjust. However, most commercial potting mixes are pH adjusted and Al's recipes for both the 5-1-1 and gritty mix are also pH adjusted.

Container grown citrus do not require a particularly acidic soil base, certainly nothing like growing blueberries in a container. Typically, just a good quality potting soil (like the 5-1-1 or gritty mix) will be adequate for their needs providing they receive sufficient supplemental fertilization.......I think that's where you may be lacking a bit. As noted, these plants do tend to have a strong nutrient demand, especially N. You may find additional input on the Citrus forum, paying particular attention to discussions on container grown citrus........the concepts are the same regardless of where one resides :-))