Indoor Citrus Grow Tent Problems

[newhomelabber]

Hello all, I purchased a Persian lime tree from a nursery here in Wisconsin earlier this summer in July. I have had a Meyer lemon tree in the past that nearly died every winter, so I decided to try to give my lime tree the best chance of surviving the winters by building a grow tent for it.

Equipment:

4' x 4' mylar grow tent
two 380W R-spec quantum board LED grow lights
Humidifier
AC Infinity in-line exhaust fan with temperature and humidity monitors


My goal was to create a microclimate that the lime tree would love by having warm temperatures, high humidity, and a potent light source. The lights work fantastic and are very intense, so much so that the highest branch is being bleached by the light (the branch needed to be pruned anyway). The humidifier doesn't work that great as it doesn't turn on half the time, so as of right now I've placed a 5 gallon bucket of water in the tent to give it some humidity. The exhaust fan works great as i set my target temperature and humidity and a sensor i place in the middle of the canopy monitors each and turns the fan on to reduce heat or humidity to the desired level.

Even with all of this, I am still having problems with leaves turning yellow and I can't figure out whats causing it. When I purchased the tree they fertilized it with a 3 month fertilizer, which lasted me until October when i refertilized it before bringing it in for the winter. I figured I would be safe refertilizing it since the plant should still be active based on the temperature and light I am supplementing it with. The plant has been in the same container I bought it in, which I would like to transfer it out of soon and repot it with some cactus soil mixture I've purchased.

Some other things worth mentioning:
- the water drains rapidly when watered, usually taking only about 10 seconds before it drains out the bottom holes.
-I water it every 2-3 days and check the soil by poking my finger down in it and making sure it's dry before watering.
-I fertilize with a fertilizer from Growscripts that is 18-5-10
-Lights are on for 12 hours per day using a timer
-Temperature in the canopy is 75 degrees
-Humidity is at roughly 32%

From what I can find online I'm thinking it might be a magnesium deficiency or the roots are maxing out the container?

I've attached pictures of my leaves and setup to help.

[Millet]

Looking at the picture of the leaves that you are concerned about, they certainly are not showing a magnesium deficiency.  I would say they are just showing that they are old leaves.  A citrus leaf has a life span of approximately 18 months.   There is no welfare program for a citrus leaf that is no longer able to fulfill its obligations.  The tree first removes the nitrogen from the leaf, which causes the yellowing,  to use elsewhere, then discards it.

[SoCal2warm]

It's a common problem people not realizing that their plant needs a bigger container.
The amount of root space should roughly match the upper size of the plant. Root issues can easily show up in the health of the leaves.

The other thing to realize is that growing inside a grow tent, there will almost always eventually be a spider mite problem.
(It is possible to completely get rid of all spider mites, once and for all, but only after repeated treatments, and it can take a long time, and if you introduce one more plant in there from outside, the problem is very likely to start all over again)

The first thing you should do is inspect the leaves of your plant very carefully to make sure you don't have spider mites. That can cause leaf yellowing.

I find that regular white (5000K) LED bulbs work better than the red/blue grow LEDs, but probably what would theoretically be the most optimal is some combination of the two different types together.

Humidity never seemed to be a problem with my citrus inside grow tents, so long as it was enclosed and the soil was kept from completely drying out. In my experience, I don't think you have to really worry about the humidity. (As long as it is inside the grow tent and enclosed, the tent will hold in humidity)
Temperature can be a little bit of an issue, but only if the ambient temperature inside your house is constantly cold. If you are living there and very often have the heat on in the winter, it shouldn't be an issue. (It's not an issue in this case of hurting the plant, but simply the citrus plant not really growing)

[newhomelabber]

It's a common problem people not realizing that their plant needs a bigger container.
The amount of root space should roughly match the upper size of the plant. Root issues can easily show up in the health of the leaves.

The other thing to realize is that growing inside a grow tent, there will almost always eventually be a spider mite problem.
(It is possible to completely get rid of all spider mites, once and for all, but only after repeated treatments, and it can take a long time, and if you introduce one more plant in there from outside, the problem is very likely to start all over again)

The first thing you should do is inspect the leaves of your plant very carefully to make sure you don't have spider mites. That can cause leaf yellowing.

I find that regular white (5000K) LED bulbs work better than the red/blue grow LEDs, but probably what would theoretically be the most optimal is some combination of the two different types together.

Humidity never seemed to be a problem with my citrus inside grow tents, so long as it was enclosed and the soil was kept from completely drying out. In my experience, I don't think you have to really worry about the humidity. (As long as it is inside the grow tent and enclosed, the tent will hold in humidity)
Temperature can be a little bit of an issue, but only if the ambient temperature inside your house is constantly cold. If you are living there and very often have the heat on in the winter, it shouldn't be an issue. (It's not an issue in this case of hurting the plant, but simply the citrus plant not really growing)

thanks for the advice! I've dealt with spider mites in the past with my meyer lemon tree, but i haven't seen any spider mites yet on my lime tree so fingers crossed it wont be a major issue this winter. I'll look into getting a bigger pot as well.

[lebmung]

-Humidity is at roughly 32%

This is very low for limes.

I keep my persian lime at 10C day / 5 C in greenhouse and is doing just fine. Of course humidity is at 90% so I barely need to water it. plants over time the adapt. A new plant needs 3-4 years to adapt to its new environment if it's young. It's better to start with a young plant than a big nice producing tree in cold climates.
I barely have any leaf loss now, maybe in spring when it gets hotter.

[newhomelabber]

Just an update, I’m still have issues with leaf drop. Since I last posted I’ve fertilized the tree and got the humidifier working where I now have roughly 80% humidity at all times, which has lead me to only have to water the tree every 4-5 days. I also lifted the tree up out of the pot and the roots were not starting to wrap around the edge of the pot, so I don’t think it needs a bigger pot yet. I also looked for mites and did not see any.

One big change is that it finally bloomed and I now have a significant amount of limes growing. I’ve heard that during a big bloom and fruit production will cause leaves to drop, but I’ve lost 2/3 of the leaves on my tree at this point, so I’m thinking of getting rid of most of the baby limes to stop the leaf drop.

[Millet]

Looking at your pictures, it certainly shows the classic symptoms of a nitrogen deficiency.  The symptoms of a nitrogen deficiency are:
totally yellow leaves with no variation of color, or YELLOW VAINS with some green out on the far sides.  In less severe deficiency (certainly not your trees case) a nitrogen deficiency shows up on the older leaves with newer leaves still retaining some green. If that was my tree, I would purchase a conventional water soluble fertilizer such as Foliage Pro 9-3-6 and fertilize once a week at first, then once every two weeks.

[newhomelabber]

Looking at your pictures, it certainly shows the classicmsymptoms of a nitrogen deficiency.  The symptoms of a nitrogen deficiency are:
totally yellow leaves with no variation of color, or YELLOW VAINS with some green out on the far sides.  In less severe deficiency (certainly not your trees case) a nitrogen deficiency shows up on the older leaves with newer leaves still retaining some green. If that was my tree, I would purchase a conventional water soluble fertilizer such as Foliate Pro 9-3-6 and fertilize once a week at first, then once every two weeks.

Thank you! Just purchased some.

[Millet]

After two or three weeks please post another picture of this tree, so that we can see the trees improvement.

[lebmung]

Your tree still looks weak.
Now in the spring it's good time to trim your tree. It will force it grow new leaves and perhaps flowers.
Tahiti lime can take down to 30F without problems.I grow them on their own roots which makes bear more fruits.
You tree looks like it was not grafted. Most probably you also have a root problem which leads to bad absorption of nutrients and chlorotic leaves.

I better approach would be to change the tree or graft it on PT, in your case for the growth tent FD, however the tree will not be loaded with limes as in the case of cuttings.

Here is mine from cuttings, the tree was so loaded with fruit that twigs just broke. Overwintered them at 30 to 50F. Fruits grow much bigger than those in shops.