Boxwood new growth turning yellow under grow light...

[Recoil Rob]

This is a small boxwood, about 10 in tall. For the last 2 years it's been battling boxwood blight here in southern NY but this summer I felt it had turned a corner. I repotted and had been pruning off dead leaves and the new growth was slow but steady. It has 3-4 chips of BioGold on the soil surface.
About a month ago I moved it into my basement with 9 other non-hardy trees, boxwoods and ficus, and put them under a full spectrum grow light for about 18hrs/day.
Under the grow light they had a nice growth spurt, new leaves all over the canopy. But in the last 5 days all the new growth has gone yellow as in the picture and are starting to drop. A few of the leaves on some ficus plants under the same light have turned yellow also but nothing like this.
I'm wondering if this could be too little water? I had been watering every other day but then I noticed fungus gnats in the area so I decided to let the soil dry out a bit to alleviate the gnats. I didn't water for 4 days, the gnats went away and the soil did not look too dried. Perhaps too much water?
If the picture can us something I'm all ears.




thanks,

Rob

 

[Bonsai Nut]

It's burning. The chlorophyll is getting cooked. I don't know if it is a photoperiod issue or an intensity issue. I would raise your lights first and foremost. 18 hours a day of sunlight doesn't happen in most part of the world so I would tweak your photoperiod as well

 

[Recoil Rob]

OK, thanks!

 

[sorce]

They seems overworked.

I guess there could be some overlap, but I'd consider these much different than ficus.

This would probably be happy cold with 12 of light if not less.

Sorce

 

[kale]

If you can nurse it back to health you should probably start treating it more like an outdoor plant and ditch the artificial lighting and such.

 

[Recoil Rob]

I have an unheated sun porch attached to the house but temps in there can get below 30˚ on real cold days. Better off there? If so do I need to transition slowly?

 

[kale]

I have an unheated sun porch attached to the house but temps in there can get below 30˚ on real cold days. Better off there? If so do I need to transition slowly?

Yes, I think itd do better outside. They are really hardy. I think theyre ok down to like 20. Just need protection from the wind really. Its actually best if they stay below 40 for a few months during their dormant period. The light requirements are practically null in the winter under these conditions. Are landscape boxwoods common in your area? I have a bonsai one and give it a little protection in the window well and it is much greener than the ones in my yard in the winter. It gets down in the upper 30’s at night in the window well. For yours I’d recommend a small cold greenhouse for your patio like the one linked below. I’m not sure how to transition it out there though since its been inside this winter. Has it been exposed to cold?

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[Recoil Rob]

In past years I had it on the porch but it did not seem to do well, I was hoping to get some growth over the winter under the lights but perhaps I am think this wrong.

It will get some light on the sun porch and be protected from wind. If it looks like temps will go down belwo 20 I can bring it in for the evening.

 

[leatherback]

Plants are cold-blooded and do not mind colling down, nor do they dislike winter. Temperate species hate coming in for winter. Don't do it. Provide the normal weather variation they evolved under.

 

[Recoil Rob]

I have moved the boxwwods out to the unheated porch but I still have a question about the ficus, they have some lower leaves turning yellow and dropping, the new growth up top, closest to the light seems good. They have to stay inside under the lights so any ideas what this could be? They are a brighter yellow than the box wood leaves which, in retrospect, definitely look burned.

 

[eryk2kartman]

photos ?

 

[Recoil Rob]

 

[eryk2kartman]

looks like too much water for me.....

 

[leatherback]

looks like too much water for me.....

It is a ficus benjamina, isn't it..?
Mine stand in a tray of water. I let it dry out once a week. The day the tray drains it gets refilled that evening or next morning. Never longer than 24h without direct access to water.

I would go for a change of location. Moving ficus and/or switching on heaters is a sure way to get a partial foliage drop with bejamina

 

[eryk2kartman]

Ficuses in general are quite sensitive to everything, to much/not enough/moving etc
I have couple and they do drop some of the foliage, mine did defoliate itself fully last year when i moved it to the greenhouse in spring, after that bounced back nicely

Its only couple of leafs, just watch it, it should be ok

 

[erich_raudebaugh]

That's a ficus. They like to drop leaves when moved, mine do it all the time. They might have been exposed to cold, keep them above 40 degrees F.

 

[penumbra]

The box belong outside and the ficus looks like normal shedding.

 

[Recoil Rob]

OK, thanks. Will watch ficus and boxwoods are in an unheated porch here in NY.

 

[leatherback]

ficus and boxwoods are in an unheated porch here in NY.

how cold does that go? You realize that ficus is tropical and long term lower temps (say 50f) is too cold?

 

[Recoil Rob]

will watch the ficus AND boxwoods are in an unheated porch here in NY. Ficus are inside under lights.