As the summer comes to a close here in Washington, my thoughts turn to where I will move my myers lemon, cocktail grapefruit (new :) and bear lime tree. A few years back, when I got the lemon tree I thought I could grow it inside my house. I was lucky that it survived at all! The leaves fell off and the branches completely died! Through the summer it flourished and grew new branches and leaves (thankfully!) Last year, I invested in a heat mat to keep the roots warm and an LED grow light and placed it (along with the new lime tree) in the garage during the winter. They both came through the winter with flying colors! Once when the weather got very very cold, I brought them inside fearing the cold would be too much for them, even with the protection of the garage. The leaves of my lemon immediately began to drop again! I quickly moved them back to the garage and it gradually grew new leaves. Today, the lemon has silver dollar sized lemons all over it (a first!) I also bought an irresistible grapefruit tree last month. All plants are doing fine outside. I don't have as much room in my garage as I'd like and wondered if there was a way to bring them inside without the worry of leaf/fruit drop. The grapefruit came with 4 softball sized grapefruits on it. I have expected them to drop off since I do not keep them in a greenhouse like it came from, but they seem to be fine so far (about a month has passed since I brought it home.) I have a room upstairs that is available, but I'm afraid the rising heated air might dry it out. Does anyone know how to successfully grow them inside? I have no problem putting up the LED grow lights and keeping them on heat mats, but even with this accommodation, my lemon tree dropped its leaves last winter. I'm stumped!
If you keep the growth medium (potting soil) at 70F throughout the winter your tree should have no problem. Because of evaporation from the container surface cooling the medium, a tree in a 70F room will not be 70F. Use the search function on this forum and look up either of the phrases shown below. Although your addition of extra lighting is fine, for citrus it really is not required (search PAR on this forum). - The best. - Millet (1,206-) WLD Winter Leaf Drop
Millet, Thank you for replying so quickly. I don't know if what I'm seeing is Winter Leaf Drop or something else. Before when I experienced problems with the tree in the house, there was no heat mat under it. I understood that the roots were possibly too cool and the leaves were drying out from the heat of the house and lights and therefore dropped it leaves (and killed off the branches) as a result. When moved into the garage, the air seemed more moist and the heat mat provided enough heat for the roots to stay in balance with the temp of the branches and leaves. Also, the LED light did not generate any additional heat from above. It seemed like a more stable climate. When I move it back into the heated house, last winter, I made sure to use the heat mat thinking that the roots needed to be as warm as the branches. Within a day, the leaves began to dry up and drop again. I didn't take the temperature of the soil but you'd think the mat would have kept it at a temp that was more akin to the room's temp. I also was careful to keep it away from any heat exchange and keep up with the LED light. Whether or not that was necessary, it was consistent from one space to another. Do you think the move into the warmer house was too abrupt and to sharp a change in temp, creating a leaf drop situation? I will search the forum as you suggested, too. Thanks again for your assistance. I always appreciate your help!
Citrus appreciate higher humidity, but do not require it. A lot of citrus varieties are grown in the hot dry heat of Arizona, and commercial citrus groves are planted along Interstate 10 in the Mohave desert, where temperatures are frequently above 100F. At temperatures below 55.4F citrus roots stop all functioning, therefore cannot supply water to the tree's foliage. Even at temperatures above, but close to 55.4F, the root system's ability to function is very marginal. My guess is when you kept your tree in the cool garage, the temperature of the growth medium (potting soil) was quite cool, and when the tree was brought into the warmer house, the tree's foliage begin to naturally transpire moisture through the leaf''s stomata, but the cold root system could not supply the needed moisture. Therefore for the tree to get back into balance, the tree had no choice but to discard its leaves. It takes quite a long time for a heat mat to re-warm a full container. Before bringing your trees in from the garage, insure that the growth medium is first warmed to a temperature at least above 64F. In some European estates, citrus tree are put into almost dark cool basements for the winter, and they seem to do fine. Of course, by doing so six months of additional growth is lost. - Millet (1,206-)
Millet, Thank you for your examples of where one can find similar dry (or much drier) circumstances in nature. In retrospect, I can see how a quick move into the house from the garage would have been a big change in the root temp, even if it was just for one day. I'm hesitant to try it again with fruit finally showing on my lemon. I swear I feel giddy just looking at them every day! Though it did grow new leaves in the garage last winter and bloom throughout the winter periodically, I never got what one would think of as exceptional growth. I know that Limes are particularly finicky about temperature. Would you advice hold true for it as well? Besides my heat mat, is there a good way to heat up the roots to above 64 degrees?
If you need to bring your tree into the house for safety, due to a abnormally cold spell, then set your trees in a location where the trees will not received direct sunlight. In front of a north window would be OK until the root system warms. Also during the winter months water your trees only with warm water (around 80F). According to research the prime growth temperature for citrus roots is 86F. - Millet (1,205-)
I had never considered watering with warm water before. I will be sure to do it this year. When I brought the trees into the house last winter for that one day, I kept them in the hallway just inside the garage door in the house with their heating mat and also their light. The only thing that changed is the location. They did not receive light at all since no window extends light that far. The house was around 67 degrees while the garage was in the cool 30's. Doubling the temp must have made the big difference. Like you said, the roots would not have been as warm as the surroundings. Even on the heat mat, it probably wasn't as warm as that. The leaves would have warmed up substantially faster wouldn't they have? Thus the leaf drop? Thanks for baby stepping me through this process. Even though I've studied up on this quite a bit I still feel like a total novice in times like this. I did search for winter leaf drop and read quite a few threads.
Millet, would misting the leaves help with the transition? I will be bringing my kumquat trees inside once the average daytime temps fall below 70. Do you think that misting can help return some of the moisture to the leaves to help with the transition? I know that moving a tree inside from a warm to a warm environment and moving from a cold to a warm environment is different. But in both circumstances will misting give the tree time for the roots to adjust to the change in temperature? What do you think?
Purdue University has conducted research on the possible benefits of hand misting citrus trees. The research has found absolutely no benefit to the tree, other than a possible reduction of dust collected on the foliage. It was determined that the life span of a mist delivered from a misting bottle by hand is of such a short duration as to offer no benefit at all. I would not bother. The most important benefit to prevent WLD when bringing in your tree in from outside, is to insure the growth medium (root zone) is at a temperature of 70F before bringing your tree indoors. This can be done by setting the tree's container in a full bucket of 80F water for 10 to 15 minutes. Don't worry about over watering when you soak the tree. A citrus tree can set in water for 24 hours without a problem. Root deteriorations don't even start until the roots of a citrus tree have been submerged for over 48 hours. Then keep your tree at or above 64F throughout the winter, if you plan to place the tree in direct sunlight, to obtain additional growth during the winter months. If during the winter your tree begins to show shows symptoms of WLD, raise the root zone temperature to up 70F, and this should stop any leaf drop. The very best to you and your tree.- Millet (1,1-99-)
