My lemon tree is couple years old and was looking great about half a year ago but since then it has dropped almost all leaves. They go brown from sides and drop off. I've cut off dried parts but all the new leaves that come also drop off after a week or two. I've also noticed that new leaves are much lighter color than they used to be and less shiny. There are couple of roots coming out from the bottom of the pot, would it be great idea to re-pot it at this time of the year? I'm afraid that otherwise there might be nothing left next spring. I'll be posting before/after pictures later too.
We are going to have to give the best advice possible from the little information that you give. Not knowing the history of how the tree has been cared for, nor seeing the tree, it makes it difficult. However, from what you state concerning the tree, it sounds like the tree is root bound, and the root system is suffering from a toxic level of soluble salts. A citrus tree needs to be transplanted into a larger container at least once a year, or the roots pruned, and the foliage balanced. When done with care, a citrus tree can be transplanted at any time of the year. Now is a particularly good time to transplant. First CAREFULLY tease the outer inch of the root ball to encourage spreading root growth, and remove any roots found circling the inside of the pot. The bottom of the pot is filled with moist potting soil so that the crown of the plant rests two inches below the rim of its new container. More moist potting soil is tamped gently into the space around the plant to fill any air pockets, using a dibble stick, then water thoroughly. Have you ever flushed the container, or has the container been flushed out in the last 3 to 6 months? Flushing is very important to the health of the tree. A containerized tree's root system needs to be flushed using CLEAN CLEAR water in the amount of 4 times the volume of the container every 3 months (4 times a year) to remove the soluble salts that builds up with each watering and fertilizing. When the salts levels accumulate to toxic levels, the result is leaf scorch and leaf drop, and the tree's attempt to replace the lost leaves ends in failure. You need to flush the container quickly. Good luck to your tree. - Millet
The tall tree does not look to be suffering from high soluble salts. What size container is the tall tree planted in? How long has it been growing in the current container? What is the potting soil made from? How many inches down deeper into the container has the potting soil settled sense you first got the tree, or last transplanted the tree? How much direct sun light does the tree get per day? - Millet
Just to avoid confusion, it's the same tree on the pictures. Left one is taken year and a half ago when it looked healthy and the right one just yesterday. Reading your replies and some other threads I realised I don't know much about my tree. After all it was just a seed from a lemon given with a Colgate toothpaste in some campaign that I out of curiosity planted. I never knew you are supposed to flush it, but will be doing so tomorrow. When you say clean water then do you mean somehow different from normal tap water that you let settle before using? Should I be concerned about fertilising later since with such amount of water I probably flush away more than just salts? It was last transplanted two years ago, meanwhile it didn't look to me as if it needed more space and so I didn't. The container is 25cm diameter, 20cm height and tree is about 80-90cm tall. Between, why is it good time to transplant at the end of summer? It has soil of 70% peat, 20% compost, 10% sand with pH 4,6-5,5. The soil has lowered about one inch but it isn't exactly adequate because if I remember correct I added one inch at some point. It's in south-facing room and I'd say about six hours direct sunlight on a sunny day in summer. In winter the shortest time of daylight is also six hours. Light conditions have been the same all those years. Thank you for all advice so far, you have such a helpful forum here.
Using tap water to flush your container depends on the soluble solids your tap water contains. After giving the container a good flush, you should fertilize when it is time for the next irrigation. When done properly and carefully, a citrus tree can be transplanted at any time of the year. I have probably transplanted trees in every one of the 12 months of the year. I do not know if it is worth repotting a citrus tree that has not been transplant for over two years. The root system must be in very bad condition. Concerning the potting soil you are currently growing the tree in, it is almost completely backwards from the recommended growth medium. A common commercial potting soil would have a formula as follows: 3 parts conifer bark (or CHC), 1 part peat moss, and one part COARSE builders sand (not play sand). I use 4 parts CHC and 1 part peat moss. The growth medium you are using is 70 percent peat moss, and 20 percent compost, both of which are ingredients that quickly degrade and become compressed. Because your medium has already compressed 2 inches (probably more) the "soil" has lost a major amount of its pore space, thus the soil Oxygen level is highly depleted, and the soil CO2 is probably near a toxic level. Peat moss and other compressible ingredients should occupy the least portion of the mixture. If you are going to successfully grow citrus you WILL NEED A SOIL THERMOMETER. If you place your tree directly in front of a south facing window during the winter months the sun can raise the tree's leaf surface to 100F+ (40C) and higher, therefore, you have to be absolutely sure that the potting soil is maintained at 65 to 70F (18 - 21C). Remember, just because your home is set to 68F, due to evaporation, the growth medium in the container will be cooler than room temperature. Absolute zero for citrus is 55.4F. So when soil temperatures are at or near 55.4F the root system of citrus are dormant, and cannot send water to the leaves to help cool the tree. Therefore, the tree drops it leaves, called winter leaf drop (WLD), in an attempt to cool down and come in balance with the root system. IMPORTANT feed your tree at least twice a month at a 250 PPM Nitrogen level, and once a month during the winter. Good luck to this tree, it is going to need it. - Millet
I'm going to try saving my tree and if not successful then at least I won't make same mistakes again. But what does CHC stand for? And how would 7% from my current fertilizer bottle compare to 250PPM, can I use simple math or are they compared somehow differently?
CHC = Coconut Husk Chips. I can't say about your fertilizer bottle, as you do not say what the formula of the fertilizer is. There are various methods of figuring PPM (parts per million), but you should not have trouble if you just remember that 1 mg per liter = 1 PPM. - Millet
Just to give you a sample calculation, for liquid fertilizer that is 10% N, 1 ml would be approximately 100 mg of N, (10% of 1 gram--although the density of the solution may be somewhat higher than 1, so the actual amt may be a little higher) There are 5 ml in a teaspoon, therefore, 1 tsp per 2 Liters would be 250 ppm. Skeet
