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Lemon tree has yellow leaves

Posted by jmcrut NC - 7b (My Page) on
Tue, Jan 15, 13 at 10:47

About a month and a half ago, I moved my lemon tree from a commercial peat based mix into the 5-1-1 mix, though I left out the peat and the lime/gypsum portions. When I repotted, I cut off at least 2/3 of the roots.

I have got a wooden dowel in the mix to monitor moisture level, and I have been watering before it dries out, every 3 to 4 days. I am feeding with FP at 1/4 teaspoon per gallon at every watering. Until about 2 weeks ago, I had been adding 1 tablespoon of vinegar to the solution because that volume was stuck in my head for some reason. I decided to check the pH and found that it was at 4.5! So I cut back to 1/4 teaspoon of vinegar per gallon. I haven't yet tested the pH of the new solution, but it is roughly 10x less vinegar so I am guessing that it is probably a little above pH 5.5 (but I will be testing soon). And when I water, probably about 1/2 of the water drains out.

I've got the tree inside facing east so the tree gets some sun but probably not enough, but it's the best I can do.

About 4 weeks ago I noticed a some yellowing leaves. Then the tree got better. About 2 weeks ago, the yellowing came back. I have been advised that leaving the lime out of the mix was a mistake but have also read that it is OK to leave out because the pH of the water matters more and I have Mg/Ca in the fertilizer solution. So, I am a bit confused when it comes to this subject.

I am looking for suggestions on what to do. Should I take it out of the pot and add some lime? Should I flush with tap water (pH around 6.5) to sort of flush out the acidity? Or does it sound like my problem is unrelated to pH?


Follow-Up Postings:

RE: Lemon tree has yellow leaves

hard to say, so many things happened within a month,

severe root pruning
changing acidity
low light conditions

RE: Lemon tree has yellow leaves

Which leaves are yellowing?

Perhaps a heavier, less frequent dose of Foliage Pro would help.

Have you checked the plant for pests?


RE: Lemon tree has yellow leaves

Hi Josh - thank you for your response

The lower leaves are yellowing - but they also happen to be the newer/smaller leaves (over the summer there was a greasy spot infection and lots of leaves were lost and subsequently replaced when new branches grew).

Why do you think a different dosing of FP will help?

I do not see any pests. There are a bunch of gnats that seem attracted to the plant - which may mean I am overwatering. Is that possible with the fast draining mixes?

RE: Lemon tree has yellow leaves

Yes, over watering is possible in your mix especially if the particle sizes are not uniform, about the same size through out the whole of the mix, or if your finer particles have settled toward the bottom.

It is also possible to over water when your plant is residing indoors since root function has dramatically slowed down with less light and cooler temps, to go along with that a pouting plant with probably consistanty wet feet.

That's why many of us here use wooden dowels or wooden barbecue/skewer sticks and check way down towards the bottom of the pot. Make sure there is almost no moisture on your sticks after you pull it out before you water again throughly. You would be surprise how deceptive it can be when you think your mix is dry, especially towards the bottom or within the root ball.
Make sure you check different ares too if you are not using a watering can with a sprinkler on the end. Make sure you don't have dry and wet spots. Your mix should be evenly moist.

What concerns me is that you have fungus gnats. I have never had a fungus gnat in properly made mixes.

Both Houston and Josh have brought up great points.

If your tree is suffering, I would address the root situation and your mix first, before you take the steps to rectify the portion of your plant above the soil level making certain there are no pests attacking the top portion which does affect root function.


This post was edited by meyermike_1micha on Fri, Jan 18, 13 at 8:18

RE: Lemon tree has yellow leaves


Thanks for taking the time to answer, I appreciate all the help and patience that all of you give to those of us just starting out.

You are right - determining moisture can be difficult. I had the wooden dowel up too high. When I inserted it deeper into the pot, I found it to be very moist indeed. I have cut back on the watering; I haven't watered for a week. Maybe that will also eliminate the gnats.

I haven't noticed any newly yellow leaves for a few days, so I am hoping that correcting for the very low water pH has also had a positive effect on absorption.

As for the fixing the mix, I wouldn't know where to start improving it. Well, I've got some ideas... Maybe, some of the bark pieces are too big compared to perlite(the bark was screened through a 1/2 inch screen and the perlite was rinsed over insect screen). Is the bark too big or the perlite too small?

Here's a picture. Any other suggestions for improvement are welcome.

5-1-1 mix b

RE: Lemon tree has yellow leaves

Hey, Mike!

Well, Jm, the bark definitely has a few large pieces, but the overall texture isn't terrible.
With disparately sized particles, the smaller pieces tend to migrate toward the bottom of the
container and make for a very moisture-retentive layer. This is where the peat fraction can help:
by "binding" the other ingredients, it allows for better moisture distribution and wicking between
particles, which makes for more even drying between waterings. I don't like peat, personally,
and have used Turface instead of peat to increase moisture retention in mixes. It's cleaner, more durable,
and receives and releases moisture more efficiently. The Perlite is a good size.

Since you'll be watering less often, and thus fertigating less often, I think a stronger dose of FP
could help. 1/2 strength to start - then evaluate after a few feedings if yellow leaves still appear.


RE: Lemon tree has yellow leaves

Thanks Josh,

I remember you telling me about the purpose of the peat from a previous post - and if it turns out I need to fix this batch of mix, I do plan to add it in. I will also increase the FP to 1/2 strength.

Hopefully that will do the trick. I will post any good or bad results once I have had time to determine how well these changes have worked.


RE: Lemon tree has yellow leaves

Well, the leaves are still yellowing, so today I removed it from the mix and added in the peat and lime that Josh previously suggested. When I took the tree out, the mix was evenly moist but the root ball was pretty dry. I think that I did not incorporate the mix into the roots very well the first time around. I hope that I did better this time -- and hopefully it's not too late.

RE: Lemon tree has yellow leaves

Hi John,
When you took your tree out of the commercial mix, did you bare root it into the 5-1-1 or did you leave some of the old mix on/around the roots?

I ask because you say the root ball was dry and you may not have gotten the mix in around the roots well enough.

If the mix was left on it could have become so dry that it repelled water.

I hope I am making sense.. my chicken is pestering me! lol..long story. lol...

In case some don't know. If moisture is not noticeable on the dowel, it helps to touch it to the inside of your wrist, like checking a baby's bottle, or on your cheek.

I too hope your tree makes a great come back!

Josh and Mike are some of the best help you can get here. :-) (Hi guys!)


RE: Lemon tree has yellow leaves

When I moved the tree out of the commercial mix, I cut off the bottom roots and then cut 3 wedges from what remained. I then used a hose to wash out as much of the old stuff as I could - but couldn't get it all out of the densely packed roots.

RE: Lemon tree has yellow leaves


You did what you could and gave your tree a much chance at survival, optimum growth and a good comeback in a much better mix as the roots will spread into the mix surrounding the mix you couldn't get out.

That's what's nice about it:-)

Hello Jojo! Josh!


RE: Lemon tree has yellow leaves

Hi John,
It makes sense now how the root ball could be dry. It sounds to me like your mix is fine.

I've planted the same as you, cutting out the wedge. Sounds like you did things right to me.

I agree with Mike. Ditto... :-)
Hi~ Mike! & Josh!


RE: Lemon tree has yellow leaves

Hi John

How did it turn out? We always love updates...:-)

Hello Jojo, Josh, and Houston


RE: Lemon tree has yellow leaves

Hi Mike - I was just coming back to post an update and saw your message.

The tree is responding very well. It is sturdier than it was the first time (since I did a better job packing the mix around root ball). It is putting out little flower buds. There was one bud that popped up in early December when I did the first potting and it just stayed the same size for a month; but now it is probably 3 or 4 times bigger - and there are other flower buds. I have not seen anymore yellow leaves and the gnats have left! I've gotten more comfortable monitoring the moisture level so I am not overwatering (at least 10 days between waterings).

It had a rough year; it lost lots of leaves and branches to a greasy spot infection. So I might pinch most (or all) of the flowers off and let it spend energy on recovering.

Thanks to Josh, Mike, Jojo, and Houston for your responses. They were much appreciated.

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