A few months back we discussed proper potting of small citrus trees. My Key Lime tree has been potted now for about a year and it has not thrived. I have had excellent results from my Meyers lemon tree, however, yielding over a dozen almost softball size lemons this year! It too is potted. My lime tree has continued to lose leaves from lower branches and I thought it just needed time to equilibrate to its new home. But, despite flowering while still in my greenhouse over the last month, it still is not showing signs of the healthy plant it should be. Almost all leaves on the bottom half of the tree are gone and I will upload photos but can't seem to do that from my iPad. Small limes are starting to grow on those bare limbs. Soil pH is acidic at about 6. Do you think a citrus fertilizer is ok to use with fruit already on the tree? I can check other nutrient levels if I need to. Thank you. Kristal

Answer #1 · Maple Tree's Answer · Hi Krystal-Sorry to hear the lime is not doing well. A couple of things may be causing the leaf drop. Changes in temperatures can cause leaf drop. Is this tree normally outdoors and then brought in during the winter? The leaves look like they are a nice green with no damage I can see that may indicate a disease or insect problem. Check the leaves closely for any small spotting on the undersides. Spider mites can cause leaf drop but not normally only the lower leaves. This is also the time of year older lower leaves will be shed. Possibly the lower dropping leaves is normal. Did the lower leaves that had dropped possibly more yellow in color before dropping? Most usually find leaf dropping on lime trees to be associated with improper watering and or nutrient deficiencies. First as you know when planted in pots the soil mix needs to be very well draining. Too wet a soil will definitely cause leaf drop. This most of the time will also cause some yellowing of the leaves prior to the leaf drop with lower leaves dropping first. Too little water will cause lower leaves to drop quickly also. The last couple of years we have found that watering can be tricky more so with the lime than many of the other types of citrus. I guess this is why my wife feels like giving up more with these than her other citrus in pots at times. Consistently moist soil is important without the soil being kept too wet or dry. This is hard when grown in pots. One deep soaking a week seems to be best with some supplimental watering in the summer months. As mentioned nutrient deficiency can cause leaf drop also. Researching when and how to fertilize the lime can drive you crazy as you can find a lot of contradictory information. Grown in pots I have found nutrients can easily be leached more quickly from the potting soils. Too much of a nutrient such as nitrogen can cause burning or can force too much foliage growth at the expense of flowering and fruit development. Too much of the other nutrients can also be harmful. If you haven't fertilized for awhile I would do so. I have found using a fertilizer formulated for citrus or a slow release fertilizer such as osmocote works best for my wife's potted citrus. When using the citrus fertilizers I would fertilize at the noted intervels but only at half strength the first few years. I like using the osmocote as it releases nutients more slowly over a longer period of time. We normally fertilize our potted trees in the spring and then again around the middle of July. You don't want to fertilize forcing new growth to late in the year as this new growth can easily be damaged by any freezing temperatures.
I can't see the actual pot size in comparison to the tree in the picture. It appears the soil medium has deteriated and sunk fairly low in the pots. Too small a pot and or too little soil will dry out more quickly not allowing the amount of moisture the tree needs. If not a larger pot it looks as though the root ball should be lifted then new or additional soil added beneath and around the root ball. Addition soil can be added just covering the exposed upper roots I can see in the pot. Just fill to the top of the roots as you don't want the tree to be planted too deeply. At this time I would check and make sure the soil is kept moist, never too wet or dry throughout the entire pot. Make sure the soil drains quickly. If not drain holes may be plugged possibly by deteriorating potting soil that has become slug in the bottom. I would fertilize as noted at this time. Make sure the tree is also getting plenty of direct sunlight as too little sunlight can also cause lower leaves to drop. Let me know how the tree is doing as we move into the warmer seasons. Let me know if you observe any spotting or in leaf color especially yellowing of the leaves. Hopefully consistency in soil moisture and fertilization will help to develop more foliage and fruit production this year.

Please ask if you have any other questions. Hopefully your cryptomeria have outgrown the problem they were having some months ago. Has the watering management and the fertilization of your meyers lemon helped to keep the foliage a healthy green now?

John)