What's the temps in that room?

What is the temps on that floor?

How many hours are you giving that tree light?

Can you put aluminum foil or reflective material around that light to make it more intense instead of letting it slip away on the outside open space?

What kind of mix is that and how long before it dries out?

Do you have vinegar?

Have you checked for mites?

Mike

Most important, do you have a SOIL thermometer? You need to know the ratio between the light and the soil temperature. It is this ratio that almost always is the cause of leaf drop in indoor potted citrus. Make absolutely sure the soil is at 70+ F.

Silica. What do you mean by the ratio between the light and the soil temperature?

What is the optimum ratio?

Mike Rivera, answers to your questions:

What's the temps in that room?
I don't have an exact read on the temperature in the room but the thermostat is usually set for 68F, so it's unlikely that the soil is warmer than that. The CFL puts off a bit of heat but not much. I do not have a soil thermometer but I will order one.

What is the temps on that floor?
Again, not an exact read but likely even a bit colder than the air as it's above the garage.

How many hours are you giving that tree light?
Did have the light on for 8 hours but cut it back when we noticed that the leaves under the light were falling off at a higher rate.

Can you put aluminum foil or reflective material around that light to make it more intense instead of letting it slip away on the outside open space?
Yes we could do that, or we could get a higher wattage bulb if necessary.

What kind of mix is that and how long before it dries out?
I don't know the exact mix as its the soil it came in (planning to repot it before returning it outside) but it's on the dry/sandy side. Water runs through it pretty quickly. Have reduced watering since bringing it inside.

Do you have vinegar?
I have some but have not used it with the plants.

Have you checked for mites?
Just checked, no sign of mites. It had some over the summer outdoors but they actually didn't seem to damage it (they moved on to my green beans and tomatoes instead.)

I also have Vladimir's question: what is the ideal environment to create as far as light and soil temperature ratio and what's the best way to create it? For instance, what's the best way to warm the soil to the right temperature? What's the best way to warm the air around the plant? How about humidity?

Silica respectfully speaking that is such a broad statement that I completely don't get.
It's impossible to keep all my indoor and outdoor trees at 70 or higher and with such little sunlight even worst. My trees would all be dead because of a lack of sunlight.

But none would drop leaves and they would grow like gang busters if I took them to my friends house in Florida, Miami that is where the temps have been above 70 for days with tons of sunshine

But I can't even think of anyone growing in containers anywhere north of that that can possibly keep their roots at 70 at all times among even my friends as far south as Mexico lately.

So I genuinely ask for those that can supply hours of sunlight or extra strong lights how much light do they need in order to match the ratio of roots temps held above 70?

What I can tell you is that my trees have never seen more than a few days of root temps into the 70's by night or by day even in summer and still hold on to their leaves well..

The roots to these trees are kept at 50 to 65 at all times during the winter with artificial lights and with what little sun I can get in winter.

Mile

My trees kept cool because of a lack of sun and artificial light...The only one that I stuck into warmer temps in a sunny south facing window in which the temps range from 70 to the 80 is the one in the next post last pic

So it sounds like the likely culprit might be root/soil temperature (although it doesn't need to be at 70). Is it worthwhile to invest in a soil thermometer and heating pad or are there better ways of maintaining the proper environment?

What's strange is that the tree does really well outdoors in the summer in the same soil. Would it be too much or too little water that would make the leafs drop? Maybe it's not getting enough light. The light meter reads that it's dark even with the light on— ~150 out of 2000 for the light reading (not sure of the unit). Is there a guideline about the right kind of light? Do I have enough wattage? The right color temperature?

Hi Jenny

Good job on the answers.

If it was my tree, I would make sure the root temps are ether cool with that amount of light, under 65 degrees or warmer as suggested above but with at least 10 to 14 hours of added lights close to that tree by at least 6 inches above...

I will be back tonight when it's slower here at work. I have much to share if you are interested)))

Any advice you have is much appreciated. After two years of this I'd like to know how to successfully winter the tree indoors.

Citrus leaves are normally warmed by the sun, or some form of artificial light (HID, Sodium, incandescent etc.,). plus the climate conditions the tree is placed in.. The stronger the light source, or the closer the light is to the leaf, the warmer is the temperature of the leaf surface, and the greater is the photosynthetic activity.. Citrus leaves cool down through transpiration. The roots send up water to the leaf and the leaf transpires the water, and thus the leaf is able to cool. Citrus roots cannot function at or below 55.2-F, and function poorly at temperatures close or semi close to 55.2-F. At these cool temperatures the roots do not send the needed amount of water to the leaves, therefore they cannot cool. Not being able to cool, the tree has no other option than to discard the leaf. Most everyone on this forum has at one time or another read the technical information sheet on WLD. It says on the WLD information text, that when a citrus tree is dropping leaves, to raise the root zone temperature to 70-F or higher, and this should slow or stop the problem.. Another method is to reduce the light, so the leaves don't warm.. As an example remember, on the WLD information sheet, it said that citrus trees in a north facing window (less direct light) had less leaf drop problems then a south facing window tree.

Silca, the information is very vague even to an experienced citrus container grower up north like me in 'containers'...

When it say's to raise the root temps, is that when the tree is getting plenty of sunlight?

When it says to put the tree in less brighter conditions, does that mean when our trees are not getting enough light to keep up with the demand with the roots needs at warm temps?

When it says to raise the temps to 70, is that for tree with very little light of one it lots of sunlight? How many hours of strong sunlight?, like those of us that can only provide sunlight all winter which is nill?

So what is the ratio of sunlight verses root temps?

It's nearly impossible for any of us to warm up the roots to our trees past 70 when you are talking about dozens of them...Know what I mean?

Because in all the years I have been growing hundreds of indoor trees I have never experienced 'WLD' unless the roots of my tree were too warm for dimmer and low light conditions as the pics above illustrated..

Thank you)

The original article published in Limette does not mention increasing the soil temperature to 70 F (21 C). That suggestion was made by Millet. This is what the Limette article said: Keeping the root temperature around 15°C (59 F) but below 18°C (64 F) seem to work best for stopping winter leaf drop. It also recommends decreasing the amount of light to slow down leaf drop.

My understanding of the article is that one should try to keep the root temps between 59 F - 64 F and to decrease the amount of light if the tree starts to drop leaves.

Vladimir, thank you))

That is what I took from it too. I guess that is why what I have been doing is working well.

My trees are subjected to temps even cooler than 59, let's say low 50's and never higher than the mid 60's. It only take a day or two at warm temps like that and I get extreme leaf drop over night.....But they all do well in much cooler temps since they are not getting strong long hours of sunlight...Appreciate that!

Mike

Jenny, if it were my tree this is what I would do))

First I would make sure that my tree is getting plenty of light to ratio of root temps..Which means if I was keeping my trees at room temps, 60's usually mid sixties by night and or day, then give more light. 8 hours of artificial light will not do it, so I would provide more light to at least 12 hours if my tree is not in a south facing window instead of cutting back which is why you are probably having an issue, that is if the root temp are above the mid sixties..For my trees, the threshold before I loose leaves in any temps over 65 without a good long amount of sunlight.

If in a south facing window, then I would turn the lights on earlier than the sun hits it, like at 5 am and then extend the lights after sundown to about 6 p.m.

Then find Mylar or some sort of reflective material and allow your plant to absorb all the light it can instead of being dispersed through the room. The light has to be intense with roots that warm under lights.

You see, if that tree were kept very cool, less slight would not matter if that makes sense. you have to make sure that if you are keeping your tree that warm, it's important that it receives at least 12 hours or more of good light and sunlight.

How cold does that floor get? How cold does it get near that window? Do you know?

If that floor is cold, which I highly doubt, because if it were cold to the point of dropping your roots temps below the low 60's, then your leaves should stay in tack which such little light

The after the light situation is fixed, I would make sure that the soil has not compacted or stays wet too long. It only takes one season with a nursery mix to compact suffocating the roots. If it does not dry out with a week it's not a good soil mix and you can almost be certain you are loosing root therefore leaves. When a mix stays wet far too long, it does not allow good oxygen exchange, or gets too dry repelling water through and through...

If it's holding too much water you have a few options but before we go there let me know how the mix behaves...Can you take a close up of it, the mix that is?

Once the soil issue is resolved , then move onto the dissolved salts that you have yet to flush from that mix.

Once that is resolved then let me know, come back. Don't want to over whelm you)

I'm going to guess I also need to repot the tree to a larger pot with fresh soil, I think the current soil is all in one large clump at this point. I've been meaning to do it for ages. Can you recommend a soil mixture? Is it safe to repot the tree during the winter?

Jenny if it a matter of life or death, I would re pot any time of the year. It's 'bare rooting' that can cause the most stress and or damage if not done right that would be better done at peak growing season around Father's Day.

If it were my tree, I would knock off as much of that old soil as possible without disturbing the roots too much. Tap the side of that root ball and let the old soil fall away, then use a good quality mix with add perlite unless you can get your hands on Pro Mix or something comparable that has good drainage and re pot into a pot slightly larger than the root ball. This is just to hold you over until the prime time to bare root and will give your roots the much needed oxygen free aerated soil with no salt deposits to get you through. That is what I would do. The less stress you cause to the already stressed roots would be prefect...In other words, just re pot, don't bare root.

Thank you. I will try this and report back.

Mike rivera, I'm glad to hear your such an experienced grower. I don't see any problem in keeping a container root system around 70-F. It is done all the time.

Vladimir, yes indeed the WLD article states raising the temperature to 70-F to slow or stop leaf drop......quote directly from the WLD article ............" If WLD persist, you may force the root temperature little bit higher, around 21-C (70- F)" .............

The WLD article also says.........."Irrigate with warm water 25 - 32-C (77-90-F)

Both of the above quotes raises the soil temperatures in efforts to stop the problem of WLD.

You will find the quotes on the WLD article please re-read.

I have about 50+- citrus trees. 10 in the ground, and the rest in containers. None - not one- has any problem with WLD.

How do you accurately measure soil temp, and does it factor in the cooling effect of water evap?

Next, other than irrigating with warmed water, how do you warm soil?? Especially when growing in plastic pots.

Silica, so how much sun or artificial light is needed in order to be able to maintain root temps at 70 degrees at times in winter, in an average home setting in order to prevent WLD for those interested ?

At what point in the light spectrum is too little light the cause of WLD when the roots are kept that warm?

Where are all your trees kept?

How much light do you provide for them?

Can we see pics of yours?

How do you keep the roots of your trees above 70 at all times? Is that cost effective? Do you use reptile heat matts for every tree? Do you have a method at keeping yours that warm at all times?

I do remember reading in that article that if one has insufficient light, to stick their trees in a cooler area and lower the root temps too, some where between 59 and 60 something degrees....That is what I do. I have also found that the low 50's with insufficient lighting causes no problem either. I have had no WLD.This seems to fit most of us since most of us can't provide the amount of light needed to prevent WLD with roots kept that warm, you know what I mean?

Thank you for your time and have a good night)

Mike rivera, you must have changed your screen name? Is this Meyer mike, or mike (sorry at the moment I forgot your full other name. Sorry did not mean to be mean. Actually your a nice guy. Take care and Merry Christmas.

Silica, for what it is worth, the quote " If WLD persist, you may force the root temperature little bit higher, around 21-C (70- F)" is not from the original Limette article published in 2000but is from Millet's posting on tropicalfruitforum.com in 2014 where he paraphrased the article. The Limette article suggests irrigating with warm water which Millet repeats in his post.

Hibiscus, I have used an electronic kitchen thermometer to measure the soil temperature. I have used seed starting heat mats to warm the containers. Soil warming cables might also work.

For what it's worth, I experienced the loss of two plants this year at root temperatures in the high 60s and low 70s even with 4 square feet of T5 CFL grow light over them. I think in general if you're not sure that your plant is getting enough light, it's better to err on the side of keeping things a bit cooler. It's all about balance - you want the roots to be able to cool the leaves if they're getting too warm, but you don't want the roots working overtime and not getting any sugars back from the leaves in return - that can lead to collapse of the root system.

I'm not as experienced as Silica or Mike (or Vladimir, for that matter), but I couldn't have easily given my plants more light than they were receiving so it seems I probably should have lowered the temperatures, though that's hard to do on the top floor of my house where the best natural light is.

Vladimir, I don't know about what you claim in your above post, but the copy of the WLD letter that is on my computer, is from the California Fruit Growers Association. The Fruit Growers published an English translation from the original German some years back in their magazine "Rare Fruit Grower" and also put it on their web site, which they got from the original German site (Das Dokument war leider).

Silica so would you agree that if one can't provide sufficient light for their trees it's better to keep the roots cooler than 70 degrees ?

Thank you and Merry Christmas to you too.

Looking forward to your response. And yes this is meyermike and thank you for notifying me..I never realized it. Must of been a fluke thingy when I used my cell the other day)
Mike

Yes, I would agree. In fact that is what the WLD research information paper is generally talking about with the tree that was growing in the north window situation. In the past some of the castles of Europe put their trees in the castle's basements in almost total darkness for the winter, and there trees continued to do well.

Silica, we are both right. Those are all the same article. It looks like it may have appeared first in The Rare Fruit Grower, been translated into German for The Limette and translated back into English and underwent minor changes as a result.

My tree's are in a room with temps at about 65*, they are elevated on 6gls containers, watered once a week mainly top of pots if that much. These 3 tree's were grafted this past spring. Lights are much higher than yours.

persimon bob

I saw your statement

"These 3 tree's were grafted this past spring. Lights are much higher than yours."

And I burst out in christmas song

Thesssse three treessss are unn-der bright lights. The tune I thought was very fitting for our Christmas citrus trees. The tune was playing on TV as I read your statement.

Steve

Steve i got the volume way up, can't hear nothing, but glad you like it!

listen carefully. It is to the tune of We three kings

https://www.youtube.com/watch?v=k8mjRxkMBkE

Steve, thanks for the We 3 Kings video. What a wonderful way to start the day. Merry Christmas.

Steve i am really grateful that my tree's inspire you to sing Christmas songs.

Very good points are expressed here. My lemon-orange tree shed the leaves two weeks ago, mostly the orange branch and I saw little brunches die back, as of today it is full die back of the main branches, don't know even will that side of the tree survive or not. It was all due to prolonged lack of light, gloomy days in a row for a week. My sunroom is not heated but it is warm, my tropical plants are growing well. You would think the more tropical type of plants should have had die back also, but no, they are fine. Go figure!

Sunshine, lol. I hear what you mean!!

Kvetch, I could not or worded it better! Great job. It's funny, I know what you mean but so hard to express in thought when I have bene going through a lot here at home.

Thank you for that fine explanation and great points. I know TONS op people who go through severe leaf drop every winter, even twig and extreme branch die back and many of their trees can look like heck by the time spring comes along. Many have trees just limping along until they even consider the temps and light thing and fine the RIGHT balance for their particular situation of environment. I think EVERY citrus in home grower should have all this knowledge under their belt if they want to avoid slow death of their trees..

Like I said, find that right balance will be up to each individual since each household or conditions is entirely different than the next. Also to the kind of lights they use, how many hours they are on, whether they use them or not, how nun their windows are, what angle the sun is at depending on the altitude, the kind of mix they use, watering habits and so on, but what you and what we have discussed is a great foundation for success..

Light ration and tem ps is something each of us can keep in mind, and we can use this info as a good foundation. In fact, I think everyone should 'bookmark' this thread as I have. It's a shame so many will miss these points and not even see this info.

For me I must keep my temps cool if I am to find success with the amount of light I provide. I provide 3 hours extra in the a.m starting at 7 or 8 and another 3 hours of lights from 2 to 5 p.m. Then I get south facing sun. The sun is at it's lowest angle, lower than southerners and provides barely anything from her until the middle of Feb. Then I can cut back the artificial lights and up the temps.

My temps are kept at 45 to 65 degrees at all times, NO HIGHER. They did raise to about 70 two days ago by accident because I left the door open and I had massive leaf drop for a day. It has slowed down now thank god!

If I decide to put the lights on all day, if I can afford it, CFL and LED lamps, and once the sun is at a higher angle, I will let temps rise again past 65. Talk about finding that right balance. It took me a couple of years and a lot of leaf loss to finally find what works for me . that right 'light' 'temp' ratio..

Mike

P.s I think I will start another thread called. 'LIGHT and Temp' ration, how is yours?

Thank you all for this information. I wish any information mentioning this had come up in my early searches of what could be wrong. Most articles just say "it's either too much water or too little water, too much light or too little light" etc. Might be technically true but not very useful when trying to diagnose a problem. This is much more actionable information!

I'm glad you found the information useful Jenny! I've learned the details of the process through this forum so asking questions is always a great thing to do when you're here. The only thing you can do here is learn anyway!

Thank you for sharing your arduous 2 year long indoor lighting experience Mike. That's one winter too many to be worried over whether your tree will pull through! I agree that everyone's environment will be different so the only way to find a good balance is to constantly tweak the lighting here and there. I'm not one to buy a heating mat or device to increase the soil temperature so I lean towards adjusting the light according to how active the roots seem. I don't have my tree near a window at all so I keep it under a pretty weak LED grow light for about 12 hours and it has been constantly in bloom. No new growth which I'm fine with but no leaf drop either! It's not until I stopped watering for a long time due to fungus gnats that I started getting leaf drop. At least in my opinion, it's better for the tree to be in a decent soil environment than a crappy one even if it is winter. So I will have to repot my tree if I want to water it without worrying about fungus gnats. I'm also sorry to hear that you are having difficult times going on at home :( My mom is currently going through a difficult family situation and I feel sad that all I can do is listen and give support. I hope you have people to support and share these times with you.

For many years now i have put my tree's in my workshop under shoplights. This year i made one change: Fluro's to Led's. Shop is heated like the rest of the interior, but set at 69*. Tree's show little effect from outside to inside growth. I even have a fruit on one of my tropical tree.

Kvetch, I am sorry to hear about your Mom too. I hope everything turns out o for you. I know how it feels to watch and not be able to do anything. By the way, great comments and I love how you adjust accordingly..You are right, soil choice does make a huge difference and lack of moisture does that to mine too. Thank you for your kind words)

Persimmombob, great work! Love the color of your trees too. How or what kind of lights are they? It seems they are much higher than 6 inches above the canopy and I see other type tropicals. It seems the room being very bright is doing just as a good job.

Jenny any time! I have been growing citrus trees inside for years and think I have mastered them at this point. Hoopoe to share from almost the North Pole where the sun does not do a thing except act like a flash light when it decides to come out.

Mike

Shoplights are bought from Sam's club, they are Honeywells led shoplights,$34.00. As you well know cheap to operate, heat zipp!

Btw big containers, small containers, i prefer big ones. Some of the 20 or 25 gls one's i use have very good drainage, i can pore a 6gls container full of water towards the center of the pot i see it flow out the drainage holes just as fast, even after 2 years or so, does not matter. Spring this year, 20 gls squat.

Very happy trees, Bob!