I live in Central Valley, CA so I don't experience true freezes. But it's 8a,8b,9a range where our freezes are 25'ish a couple times in winter. There are varieties of citrus that can stand colder weather -- but what is usually discussed is the upper foliage and fruit. Any of them in typically sized containers are going to suffer root loss if unprotected below 30F weather, which can severely compound the problem if even lower. Unless you are burying the entire pot in-ground (or creating a giant mulch mound around it), it is best to continue your practice with relocating the citrus of the extreme cold. If you are asking about in-ground plantings, the satsuma mandarin is supposed to be very cold hardy, so are kumquats, and many lemons will regrow the canopy if the rootstock was protected adequately (much easier than protecting the entire tree) during rare freezes. However, you might visit this link to check out his opinions about cold hardy citrus, esp from WA folks asking about it. He thinks it's a myth. Here is a link that might be useful: Cold hardy Citrus a Myth?

miyami, it does look like Gummosis to me, which is Foot Rot caused by Phytophthora. You might be able to save your tree, but this looks pretty extensive, sadly. There are treatments you can apply to the trunk to save the tree. Copper based fungicides applied to the trunk, Ridomil Gold applied to the soil as a soil drench (expensive, and hard to find, as it's commercial, but it is treatment of choice). The feeder roots are at the edge of the canopy, don't worry about what you're seeing by digging around the trunk. No, yellow leaves are not normal and have zero to do with our wonderful California sunshine - that should make your leaves green, not yellow :-) Your tree is seriously underfed, and is in need of regular fertilizing at the canopy edge (dripline) of your tree. Use a good quality citrus fertilizer that contains micronutrients. Also, I can't see because your photos are too little, but it looks? like your tree has algae growing on the trunk? That would make me suspect it is getting hit by sprinkers? If so, this is why you are getting a fungal infection on the trunk. Citrus do not like to get hit by sprinklers. You should be drip watering the tree, with 1 to 3 deep waterings a week, depending upon how hot it is (more in the heat of our summers). And, any grass under the tree should be removed, as grass will compete seriously for nutrients, and cause your tree to become nitrogen-deficient (hence the chlorotic appearance). Water is the culprit here. Too much of it, and in the wrong places. Patty S. Here is a link that might be useful: UC IPM: Gummosis

Hi guys, I wanted to pass along an e-mail response I just received from Dr. Toni Siebert on the question of whether there were any negatives we should consider to planting citrus too deeply. Dr. Siebert works with Dr. Tracy Kahn at what is arguably the premier citrus research center in the world (the Citrus Experiment Station at UC Riverside). The institution has been planting trees since the early 1900s. Here is Dr. Siebert's reply: Hi Tim, In our experience, planting citrus trees too deeply in which the soil and any moisture covering any portion of the trunk is a disadvantage. Exposing the trunk to constant moisture by planting the tree too deep causing water ponding or waterlogging of roots, has been known to be associated with the invasion of root tissue by wood rotting organisms, usually Phytophthora or Fusarium fungi. The general rule when we plant our citrus trees is to only plant the tree to a depth at which the tree can set evenly with the soil line, so the depth depends on the size of the pot the tree is being grown in. In our citrus classes, the planting instruction that are given to students are as follows: "1. Dig a hole that is 2-3 times as wide as the diameter of the container holding the tree. While the tree is in the container, find the area where the stem merges with its root system. Measure from this area to the bottom of the container. Dig the hole as deep as the measurement. Save the soil from the hole to use as backfill. If the hole is deeper than the measurement, prior to placing the tree in the hole, backfill with enough soil to hold the tree slightly higher than the measurement. Firmly press the soil before setting the tree on it. 2. Position the tree. Carefully remove the tree from the container, supporting the rootball. Place the tree in the hole and center it. Check the hole depth. It is most important to plant at the same height or slightly above the height of the soil level in the nursery container. Cut any circled or kinked roots. Loose roots should be positioned facing down in the hole. 3. Fill the hole. Remove any rocks, grass or debris from the dug-up soil. Break up clods. Add backfill soil, firming it around the lower roots by hand. Continue filling and firming 4-6 inches at a time. Press gently with the top end of the shovel handle. Soil should be firmly, but not tightly packed. Create a basin to hold water that is just a little larger than the rootball. Build and compact the edge of the circular basin to a height of 6 inches. Pull out all weeds in the basin. 4. Water After the tree is planted, fill the basin with water. Check the original soil line one last time. If the tree does settle, now is the time to move it back to the correct position with soil level against trunk at the same level that it was in the container." Best, Toni Siebert toni.siebert@ucr.edu Although there are root stocks that are more resistant to Phytophthora (e.g. Trifoliate orange) rendering this possibly as less of an issue, there is evidently no cure for Fusarium fungi. Therefore, I would still practice caution by heeding the above planting guidelines of these researchers. jkom, I do have a question for you. Since I recall you mentioning that one of your Meyer trees was actually derived from the seed of a fallen neighbor's fruit that had successfully germinated, I'm wondering if you've ever seen the trunk/root crown interface exposed? I ask this since I'm curious what is the natural exposure of a citrus (in this case a Meyer) tree's roots when it grows unaided by humans. If you currently do not see the upper adventitious roots, since you're in the Oakland hills, could erosion have buried the trunk over the years? Cheers, Tim

keodark, if you find that "miracle" potting mix, please let us all know, lol! Seriously, there just isn't anything out there that will fit your requirements. But, I understand trying to use the KISS method. I don't have the time to mix my own container mix, either, and, here in S. Calif, I need something that is actually more water retentive than gritty mix or 511 mix. Farfad's is probably your best choice, but I can't find it anywhere in my area, sadly. So, my next choice is EB Stone's Cactus Mix, which is got fir bark in it ( Fir Bark, Lava Rock, Canadian Sphagnum Peat Moss, Sand, Redwood Compost and Mushroom Compost to be exact.) So far, my container citrus are doing exceptionally well in it. I've even brought a few abused citrus back to life in it. Fertilizing - you have to fertilize container citrus even more frequently than in-ground citrus. I use the new Osmocote Plus, which has a decent N-P-K ratio for citrus plus the micros, and I also will fertilize with a small amount of regular citrus fertilizer (Gro Power Citrus & Avocado Food) every 3 months during the growing season, too. Citrus are pretty heavy feeders, really needing nitrogen, so if you want to grow citrus in containers, and keep it as carefree as possible, this is what I do, and so far, it's working very well. I anticipate I'll need to re-pot in a few years, maybe 3 or 4 if I'm lucky, since I have my citrus in a little larger containers than some of the really serious container citrus growers on our forum, but I can do this because I'm not moving my citrus in and out for weather reasons. They just sit on my patio all year 'round. So, saves me a few re-potting sessions. Before: One year later: Before (this was a very coveted, rare citrus, I about had a cow when it came to me in this condition:) About 2 months later: Patty S.