I purchased a set of two 4-5’ tall Meyer Lemon trees online in September. I scored the root bulbs and repotted the plants in pots lined with stones on the bottom using Miracle Gro potting soil. They are in the corner of my apartment in Milwaukee WI with windows all around, but facing northeast. To supplement the amount of light available to the plants I purchased two Chinese 600 W full spectrum LED grow lights with good reviews from Amazon. The lights run on a timer with a schedule of turning on at 6:30 AM and turning off at 8:30 PM. Both trees dropped probably 30-50% of their leaves in the first couple weeks, which I attributed at the time to the stress of being repotted in a totally different climate, and I thought that perhaps I was overwatering so I tried to be more careful about waiting until the soil appeared to be dry to water. The trees continued dropping leaves and eventually I looked at them very closely and saw that they were infested with a large number of spider mites. I treated the plants with a water suspension of diatomaceous earth, which seemed to help. The plants began to rebound and bloom, although they would intermittently (every 4-6 weeks) drop leaves. Eventually I noticed that the spider mites were back. I treated the plant again, this time with a potassium salt based spray and that seems to have permanently killed off the mites. I refertilized the plants with citrus fertilizer at the same time. After this both plants rebounded and looked great for a month or so. About 1 1/2 week ago, I was traveling and let the plants go about 8 days or so without any water. The leaves of both plants had started to yellow before I was able to water them. I have been watering the plants every 3-4 days since then, but the yellow leaves did not get better and most dropped off. Both plants are now very sparsely populated with leaves and I am worried they will die. I also noticed that there seems to be a proliferation of small flies near the soil and water trays of each plant. It’s hard to tell if I am watering too much, too little or doing something else wrong. I am all ears for any suggestions! Thank you.
This is the time of year when the plants would normally respond to increasing light levels by budding out with new leaves. You would begin to feed with a liquid once or twice a month, depending upon the amount of growth you see. Lots of new leaves and flowers, feed every other week. Just a little growth, just a little fertilizer, like once a month. Feed until ~September. Change your water regime to adding 25% of the volume of the soil ball every time the soil is dry to the touch. Ideally, none would leak out the bottom into the tray, it would disperse into the whole soilball. Plants prefer wet, dry, wet, dry cycles and the black flies don't. They lay their eggs in the soil and the larvae eat the roots. They are hard to kill while flying around. Put a dish of Dawn dish washing soap on the soil surface, they love the smell. It's like the tar-baby. When they land on it, they can't get away. Spidermites are problematic, but this is your lucky day. Since you have so few leaves, you can do an emergency spray with Pyloa or any horticultural oil, several times. First, cut all the leaves off at the base of the leaf, leaving the stem on the plant. Flowers, too. Leave the fruit which may or may not survive. Assume that there will be lots of spider-mites and eggs on these leaves, so put down a bunch of newspapers taped together to catch those that fall off so they can't just hide temporarily in your carpet. If you have a hand held shower spray, tape a plastic skirt on the lower part of the trunk so that you don't collect water in the pot. Spray generously with warm to hot water a few times. Spider-mites hate water and you can wash many of them off. Spray with a mixture of dawn at ~10-15% in water, let dry, rinse, repeat. Next, mix up the hort oil according to label directions with the right amount of water. If you are able to rig some kind of shield, spray the plants and make sure you get lots into the crevices of the plant where the spider mites like to hide. Spraying in an apartment may not be a good idea. It may be more practical to paint it on, generously, a few times over a couple days. don't worry about the excess that drools into the soil because you're going to drench the entire upper soil, too, to about 3 inches deep. The drench will kill the Black-fly larvae, too. Just for this process, let the plant stand in the excess that drains out the bottom. (Next time, don't use stones or anything else in the bottom, just soil. The stones don't really provide better drainage and make good places for Black Flies to hide.) Black-fly and Spider-mites can be eliminated by this process, but remember that they are both hermaphrodites. If a lady can't find a guy, she can change her faculties and fertilize herself. And you've got a million, again. Watch in the future for what looks like little single strands of spiderweb. That's how they get around, on thermals in the air. There will be one at the end of that strand looking for home. Repeat, ad infinitum. Next time you go away for a while, buy a giant size clear plastic bag from a hardware store (a leaf bag). Put the whole plant in a bag, give it the normal amount of water, seal the bag, and go away for up to ~4 or 6 weeks. They may have some grey mold when you get back, but that doesn't hurt the plant and will die in the dry air when the bag is taken off.
The natural light in that location is not sufficient to sustain the trees so it's good that you've added artificial lighting. However I can't comment on whether that is sufficient. The layer of rock should be removed the next time you repot. It does not improve drainage but has the effect of raising the perched water table in the container: The Myth of Drainage Material in Container Plantings. (.pdf) The potting mix you used is not the ideal as citrus prefers a more porous mix. With that in mind 'standard' potting soils can be amended with various materials such as perlite, medium sized bark chips, and calcined clay. When watering it is suggested that a small amount of water be seen to drain from the bottom in order to facilitate the flushing of excess salts from the medium. This excess water should be then be removed; do not allow the container to sit in water. Lift the container slightly after such a watering to get a feel for its weight then water again when it feels relatively light. This method allows you to know when the tree needs to be watered. The flies you're seeing are likely to be fungus gnats. They are usually an indicator of an overly moist potting medium. Their numbers can be greatly controlled with a more judicious watering regimen, without having to resort to more drastic measures. Allow the soil to dry somewhat between watering. It should be relatively easy to deal with the spider mites at this time because of the little foliage remaining. Rather than horticultural oil, which may be problematic for indoor plants, insecticidal soap can be used. Follow the instructions on the label and be sure to repeat the spray every 7-10 days until they are gone. I recommend buying the concentrate and mixing the solution yourself as it is much more cost effective. Feed the trees on a monthly basis using a water soluble fertilizer at full-strength during the active growing season and half-strength at other times. Select one that includes micronutrients. An NPK ratio of 5-1-3 is recommended for containerized citrus. However you may want to withhold feeding until the tree shows signs of recovery.
Almost forgot to ask. What is the day and night temperatures where the trees are? Do they vary with the seasons?
Thank you both for the assistance!! Based on your recommendations, I have been much more judicious about watering — waiting until the soil feels dry not just at the surface but also down an inch or so. This has eliminated the fungus gnats and although the trees are still not thriving it seems to be doing marginally better. I have been using insecticidal soap to eliminate the spider mites and they are almost gone. The loss of leaves has slowed down somewhat, and encouragingly the tree continues to bloom and even has some new shoots of leaves. However, both the trees continue to lose leaves at a significant rate. I have observed that there are two patterns of leaf loss — the more common one seems to occur in clusters to a number of leaves close to each other and manifests as yellowing that starts at the base and progressively moves up the central vein of the leaf. Eventually the base is totally yellow and it falls off the tree. I have attached a number of photos showing the progression of this. The second pattern seems to cause the leaf to become “bumpy” and the very tip of the leaf becomes brown. This is less common and occurs randomly throughout the plants. The last couple photos show this. To answer your question, the indoor temperature of the room that the trees are in varies between about 70-80 degrees F. The temperature is fairly constant day and night, probably a bit on the warmer side at night time. I am concerned that the soil and potting method I used is very suboptimal. The bag says it is designed to prevent “over and underwatering” so I think it has something in it to prevent it from drying out between waterings (which seems to be a negative). Here are my questions: 1. What might be causing the leaf drop pattern #1? 2. What might be causing the leaf drop pattern #2? 3. What would be the best type of soil and additives (and in what percentages) to use if I decide to repot the plant? Joe
I could only attach 10 photos to the last post. The last post shows pattern #1, this post shows pattern #2.
I wonder if this might be a problem of nitrogen deficiency due to over-watering. The first half of the following document explains what might be happening: The Answers to Common Citrus Questions (.pdf). In your case: The trees have been over-watered, possibly suffering some root rot; Leaves are showing yellow chlorosis and dropping; The leaves that remain on the tree, as seen in the second photo in the first post, appear to be the newest ones. You may be able to find more information by searching on the phrase "yellow vein chlorosis" relating to citrus. Suggested material for amending the soil can be found in my first post. I can't recommend a specific recipe; it depends on the material on-hand. The resulting mix should be porous and fast-draining yet moisture retentive.
I repotted the plants this afternoon. I carefully shook out the old soil from the root bulb and repotted with Miracle-Gro Cactus Palm & Citrus potting mix (ref), except I added 3/4 cup of Espoma Citrus-tone (ref) to each 8 quart bag, and also added additional perlite. I did not use a drainage bed of rocks this time. The roots looked OK to me... I didn't see any obvious "rot" or slimy growth. I have had a tough time finding a 5-1-3 fertilizer. I found a 25-5-15 fertilizer that is made by J.R. Peters... I attached the specifications to this post. It has the "perfect" macronutrient ratio... but I'm not sure if the micronutrients are correct. It looks like it doesn't contain calcium, sulfur or magnesium... which I believe are needed for citrus right?
The J.R. Peters fertilizer is a perfect 5-1-3 ratio - good find. Some people supplement their fertilizer with an occasional epsom salt solution thus adding magnesium and sulfur to the list of micronutrients. Note the Espoma product already contains these two elements as well as calcium. However I don't know how one would determine the proper mix to use when two different fertilizers are involved. You may want to do some research.
Great thanks I will look into that. I think I am going to test my water as well to see how much calcium is in it to start with — I am watering with tap.
At this point I would wait for signs of recovery before doing anything more. Do not feed the trees any further particularly since you're already added some slow release fertilizer to the medium.
Unfortunately, the repotting intervention seems to have done more harm than good. Essentially all of the leaves have dropped, and now some of the twigs are turning brown. Even the new shoots of leaves have died off for the most part. Anything I can do to save them or are these trees goners?
I would recommend removing the fruit, it takes nutrients the plant needs for recovery. If it does not recover the fruit would be lost anyway. Also, prune back. At the very least cut off any dead branches as they can sometimes become infected with fungus.
It's not looking good. If the trees are not going outside, try moving the lights to a position just above the branches or even to the side so that the branches get as much light as possible.
No these will be inside-only plants. I live in an apartment and don’t have a suitable place to put them outside. I pruned all the fruit off the branches as suggested, and will move the lights closer to the branches tomorrow. Is it possible that these trees have citrus greening? The leaves have (had) chlorosis and the twigs are now experiencing dieback from the outside in.
Possible yes, but quite unlikely. Chlorosis is normal when the tree is trying to drop its leaves due to some imbalance. Heavy mite infestations and root rot can certainly initiate such an imbalance. Twig dieback can also be initiated by the tree under some conditions.
