I moved my Meyer Lemon indoors about 2 months ago and didn't have any problems initially. It had been relatively warm indoors (70-80 F) and the Meyer was doing pretty well. Over the past few weeks, we've been getting extremely cold temps (for Atlanta at least) and the temp inside has dropped to the low 60s and I've noticed some WLD. I have a digital thermometer and am now able to measure the temp of the soil and would like to adjust it accordingly.

My initial readings for the soil temperature have shown a range from the high 50s to the mid 60s for the soil temp, depending on time of day and the location of the plant. Based on previous posts I've read regarding WLD, I assume this is the cause of my leaf drop. I have now wrapped christmas lights around the pot and this has significantly increased the soil temp.

What would be the optimum soil temperature to allow for good growth indoors without supplemental lighting near south windows. From the previous posts, there seems to be a few temperatures that keep reappearing. I've seen both 64 and 70 F mentioned and was wondering if a higher temperature was better or tolerable. My initial tests with the current setup now has the soil temperature reaching 81 F after 5 hours. I wasn't sure if this was too high so I unplugged it and am keeping it away from sunlight until I get the temps right.

i have all the root temperature (check the center) between 75 and 90F (the heater mat thermostats are not that quick to respond!), i have had no WLD this year, with or without growlights

I have some on dog bed heaters, they vary at between 68F at night to 74 F in the day (as they are in a heated room day tme air tempertaure at 28C most days, 15 most nights ) , they are fine as well

the root temperature seems fine, even with no aditional lighting , even at 90F but at 60F leaves fall off

The other half of the WLD prevention is to avoid direct sunlight. You don't have to avoid sunlight, jus direct sunlight. My key lime seedlings are kept outdoors except when it drops below mid 30s (like tonight), but they are under a shade cloth--they get about 40-50% sunlight, but eventhough the roots are often below 50, I do not get WLD, because the sunlight that reaches them is filtered and diffuse. I will even get a flush from most of the seedlings in the middle of winter.

Thanks for the information and suggestions StarLoc and Skeeter. Glad to hear they can go up to 90 (at least for short periods) without any adverse effect. I did a trial run last night and reached a steady temp of 84 F. I'm still working on getting the wrapping optimized to keep the soil temp between 70 and 80 but I think this solution will work well for me.

Skeeter, thanks for the shade cloth suggestion. I too have key lime seedlings but they are sitting on the window sill of a south facing window. It can be a bit drafty at times and they don't look as healthy as before. I will try that as well.

So I have the Christmas lights wrapped to give a soil temp of about 70-75 F but the tree has still dropping a few leaves over the last few days. Does it take a few days for the tree to acclimate to the new soil temp? I'm keeping it out of direct light for now.

A citrus tree will always drop a few leaves year around. The efforts you have taken should bring an end to your tree's WLD rather quickly. I had a Kumquat that started to drop leaves last week. I moved it to the heating mat (actually a 10-ft. long plastic heating roll) that is set at 80F. The leaf drop stopped in 2 days. - Millet

Don't you find these "heat mats" dry soil out from the bottom (or where ever they'd be in contact with the container), where the heat sourse is? I've found that to be true in smaller applications.

Cheers, Barrie.

Barrie, no I have never observed heat mats drying the medium from the bottom. The drying still is from the surface. - Millet

I have found that the bottom drys slightly in large pots, but only on pots that i have cut lots of drainage holes in the sides, once away from the drainage holes it doesnt dry out any different till the top surface of the pot i think its a good thing and doesnt cause any problems.

The water if it gets hot, works its way upwards and hits colder soil, condenses and runs back down, like in distillation, unless you have great big side holes

I believe that anyone growing citrus should buy a heater mat, everyone should have one

Heater mat + decent potting mix (chc or perlite) and a tree has 99% chance of survival, without the mat id guess at 99% or more of those purchased will die first winter they get too, from cold roots and overwatering / wet compost

After about a week, the meyer lemon is still losing a few leaves a day but it's not nearly as bad as before. One interesting thing I've noticed is that it looks like it is only the older leaves which are dropping (not sure how old they are as they were on the tree when I bought it this summer). The leaves that are from the new growth this summer seem just fine. I hope this is a good sign and the tree survives the winter.

This past week or so we've had pretty nice temps and I haven't had to heat the pot (soil temp stable at about 75-79 F). Tonight we're getting a quick freeze though so it's back to the christmas lights.

Quick question for you, Starloc...where did you get your heating mats? All of my citrus are now indoors, and, though I haven't had a single leaf drop (in fact, have had quite a bit of growth!) it would be something I would like in the future.

Cheers

I get everything from the internet as shops and nurseries are always overpriced, the heater mats (with thermostat) were from garden4less.co.uk , there may be cheaper places but when i got the last one earlier in the year they seemed cheapest.

http://www.garden4less.co.uk/search.asp?scat=&stext=heat+mat&stype=sbrand=sprice=&pg=2

I also use dog bed heaters from on ebay, you cant alter the temperature, they seem to run at about 74F , but are ok to use, i get steel rigid ones called petnap but you can get vivarium flexible heater mats as well., the metal ones are about 12 inch by 15 inch, so not good for many plants, i use them under large plants or for seedlings,
most plants go on `real` heater mats as i can all ssorts of sizes , i use 1m by 2m ones and line the plants up 2 accross and about 6-7 plants (in 12-20L pots) along, so you can fit a lot on them

I have read all the posts [I think] about WLD and have started using Christmas lights around the pots and around some small citrus in the ground too. Used more outside under cardboard boxes but winter has been pretty mild in central Alabama except for a few cold snaps. I move all lights before watering outside but have been bringing citrus in pots in during cold snaps but have them in extra bathroom now. Do I have to unhook and move Christmas lights every time I water? I will probably buy a heat mat or two after the 25th of Dec. I really like the idea of the lights but I keep stepping on them in the small bathroom-they pop great! I'm a little unclear how to wrap the large pots the citrus is in-thats my 2nd question.Thanks for all the great information so far !! TOM

As I write this I am in South Florida Interesting topic. Before I left home, I brought a few 1 gallon plants in from my garage (it does not freeze) into my living area. Before moving the plants indoors, I placed the pots in warm water for about 20 to 30 minutes. My thinking was to stimulate the roots so that the foliage would not dehydrate when exposed to indoor temperatures. We will see when I get home whether my logic worked!

Greg

I am new to this forum and new to citrus trees. I live in utah and just bought a 7 gal kamquat with fruit, 7 gal meyer lemon, 5 gal naval orange. They will be inside my apartment do I need to do something with the soil temp? My apartment is about 65-70 now but will heat up in the next week with increased weather temps. And what is qualified as direct sunlight? I have them in a south east window and i want to do everything i can so that the myer and the kamquat will not drop there fruit. I have read about watering and fertilizing. Does there any other suggestions?