The Tropical Fruit Forum

Hi,

I'm growing several types of dwarf citrus trees in my grow tent during the winter (a. Long with other types of plants) under 2 LED lights and experiencing some problems. First, the types of trees are Meyer lemon (2), kaffir lime, bears lime, and Australian lime.

The problems I'm experiencing are pretty much the same for all the trees (except for the Australian lime which is newer) - - leaves are looking bleached and mottled, nothing like the way a nitrogen deficiency looks, and the texture of the leaves is no longer smooth but rather coarse and rough. None of the trees had these problems before going into the grow tent and I'm fairly certain the problem is related to the grow lights. The thing that's really puzzling me is I have the lights further away than they should need to be and other full-sun plants like avocado, fig trees, birch tree (don't ask) are all fine. For those of you familiar with PAR light meters, I have an apogee quantum flux meter which is giving me readings of around 250 umols around the top of the plant canopy. Direct sun measures in the range of 800-2000 umols, and I have other plants closer to the light with no ill effects. Also, I should mention that I run the lights 18 hours on / 6 off. Anyone know if this is too little rest time for citrus trees?

I will post pics of the leaves soon but have visual impairments using computers so doing this without my eyes and having my wife help me later to post the pics (also please pardon any weird spellings, etc). I should also mention the one of the Meyer lemon lost 3 leaves and they all had light brown or yellow spots on them. I'm not even going into my whole regimen of fertilization, etc, because I highly doubt this is a nutrient / micronutrients issue as it would be a weird coincidence if everything went to hell at the same time when they were all fine before. I'm very conscientious with watering, meaning I only water when it's needed and I've got several ways of figuring this out (bamboo skewers, how the soil feels, container weight, etc). Humidity is always around 60% and temperature is around 80 degrees. Airflow is good, with internal fan circulating and intake replenishing air several times per hour.

I should also mention that the LED's are the newest technology on LED on chip, which produces mostly red / blue light with some infra-red and uv light thrown in for good measure. One of my biggest concerns is whether citrus might react different to this spectrum combo than other plants do. Anyway, sorry for the rambling post, part of the problem with using this software to use computers / phones is I have to write from memory and can't really revise.

Thanks in advance,

Frank

Hi, this is my first post and as you can see I don't have profile info filled in yet. In explanation, I am unable to use computers / phones without software that reads everything to me so it's extremely hard to get anything done. My wife signed me up to this forum after I read this entire thread and wanted to chime in and ask some questions. By the way, I'm able to see just fine, but for neurological reasons cannot use screens (and being a former software engineer this has been a hard past 5 years!).

Anyway, I live in Portland, which is supposedly zone 9a, but my little microclimate near Laurelhurst Park in SE Portlandalways seems to be at least 5 degrees warmer than what Google or other weather sources report and I think my thermometer is accurate and well-placed. So when we just experienced a handful of days in the mid 20's or thereabouts, my thermometer read around 29-33.

Even so, I'm obviously concerned about temperature and want to experiment with pushing the limits like you guys have been doing and want to grow citrus outside that's not yuzu. I currently have a couple of Meyer lemons, a kaffir lime, Persian lime, and Australian lime in pots in a grow tent, and all of these go outside in the summer obviously. I have a space in my front yard (south facing) where I'm seriously contemplating trying an owari Satsuma. I don't mind spending a little money upfront if it saves me some heartache later so I was considering buying a 6-7' tree from fast growing trees. I've ordered from them before and found them relatively cheap and of good quality, and I think this tree would only be just over $100.

My real question is around methods of mitigating cold snaps and maximizing production, etc. I'm not a real DIY guy (although I have a shop full of tools and can use them) so I'd like to know if there are any products out there which are semi plug-and-play. I've heard people talk about using incandescent Christmas tree lights as makeshift heaters but I cannot imagine those can even be purchased anymore and would think something like heat tape or a similar product must exist for this purpose (?). And then what about creating a single-tree mini greenhouse enclosure? Are there products that can be purchased which achieve this purpose? And would there be issues with potential city code violations, being this would be in my front yard? I've seen cold frames in front yards but never a 10' high enclosure around a tree. Also, if a product does exist (or even if one were improvised, wouldn't wind be a problem?

The tree would be about 5 feet from a power outlet so plugging something in wouldn't be an issue.

Thoughts, or is this not feasible? Thanks, and I hope to get some help completing my profile soon!

Frank