The Tropical Fruit Forum

Hello from VA,

We've had this potted lemon tree for several years but decided for the first time to bring it in for the winter.  Previously we’d just cover it with burlap and drag in into our shed.  It’s managed to survive 3 winters here in northern VA even though we get plenty of weeks of well below freezing weather – down in the teens and 20s often enough at night.  Likely, because of this, the tree has always looked a bit haggard and spindly - not very lush; it has six very slowly growing lemons.  In spring and summer, it sits in a good sunny location, but I think the cold winters have taken a toll.

This year we made the considerable effort of bringing it inside - about 3 weeks ago now - and to buy and put it under grow lamps.  I've been fussing with just where to put the lights, how far from the tree.  (I should note here that where the tree sits, in our basement, it gets very little natural light, almost negligible). 

I purchased two of these dual head grow lights from Amazon: "Grow Light with Stand, Lordem Full Spectrum LED Plant Light for Indoor Plants, 200W Dual Heads."
Here are the listed specs at Amazon:
Input Power: 60W
Lumen: 4500 lm
PF: >0.9
PPFD/1 Feet: 685μmol/m²/s
Color Temperature: 4000K
(Beyond this, the manual simply says to keep the lights at least 9 inches away).

At first, I had the lights about 9 to 10 inches away from the top of the tree on one side, aiming down.  But I noticed what *appeared* to be sunburn on some leaves – yellowing/ browning tips.  But from my research, this could also be caused by other things.  And oddly, some of that yellowing and even the browning tips occurred on leaves farther away from the lights.  (And the lumens from these lights drop off very quickly with distance).

Honestly, I think it just may take some time to get it dialed in.  I watered and fertilized it (first time it's ever been properly fertilized) with citrus fertilizer (Miracle-Gro Shake N’ Feed Citrus) a few days ago (it was finally dry down to about 3 inches into the soil after bringing it in).  Part of the problem is that the tree wasn't in great shape when we brought it in, and it took a bit of a shock in transition as well - a handful of leaves went yellow and dropped off.  It does appear to be perking up maybe – most of the leaves are a light-green shade – not awful looking, but not much deep green.  The tree did sprout 5 new buds down low at the rear – and these have been exploding, really taking off – one good, healthy sign.  But I'd love to get some advice about these lights.  So, there is a lot going on here: tree never really in great shape in first place/ survived several winters outside, shock of coming in from outside, now the grow lights, and fertilized for the first time (and because it’s slow release, it may take some time to take effect).

I was hoping to see or hear about other lime tree setups – see how close others put their lamps of various wattages or lumens output.  I've moved the lights further away from the tree for now.  I have a light meter app (who knows how accurate).  And with the lights about 14 inches away, I measure about 9K lx at the closest leaves to *each* head.  But I have another dual-head lamp that sits by a jade box next to the lemon tree.  And one of its heads aims directly toward the lemon tree as well (but about 20 inches away) – I’m only reading about 3K Lx from it at the tree – but still, basically I have three lights aimed at the tree, all told.  But the overall avg. covering the entire tree is prob. somewhere around 2K lx or less.  (For what it's worth, the jade plants don't seem to mind the lights being closer - in fact, seem to like it best with the lights about 9 or 10 inches away).

Is it even possible to burn this plant with these lights unless they are right up against the plant?  The lights themselves put off very little heat - you can put your hand right up on the face of the bulbs and leave it there, i.e., warm to the touch, but never hot.

Thank you very much in advance for reading and any advice, Gary in VA

(The pics:  In the first pic, you can see the current lamp placement with distances.  And in the second pic, a full shot of the tree with an arrow pointing to the new buds and another arrow pointing to a branch that broke at the bottom that I taped up – thus the yellowing leaves on that branch.  It has a lemon at the end, and I hope there was enough skin left on the branch to heal up – there appeared to be, but time will tell.