Sorry if this is long-winded for a first post, but here it goes. I live in the south hills of Pittsburgh (zone 6) and have a yuzu tree on order from Stan for my wife. Her parents have a large one in Japan and I thought it would be outstanding if I could have fresh yuzu here for her (and her Japanese friends) to use in cooking, etc.

That being said, although yuzu is "cold hardy", I'm well aware that it's not going to do well in-ground and unprotected. The south side of my house is extremely shaded (only ~4 hours of sun per day in the summer), so I have little choice but to plant it in the front yard a good distance from any potential shelters or micro-climates. However, reading about others' successes has led me to optimistically give this a shot.

The tree is on order and I have a few days before it goes in the ground, so I was hoping to pick everyone's brain (particularly frank_zone5.5 in Massachusetts) as to what a potentially viable (and relatively frugal) approach might be.

I have had many other successful experiments (like raising a large vegetable garden on 4 hours of sun per day with 12 deer and families of groundhogs and rabbits in my backyard, converting two of my 20 gallon freshwater tanks into reef tanks with ~60 different types of corals for probably 5% the cost that most spend, teaching myself computer networking/programming, how to read Japanese, etc), and I know that research, leveraging others experiments, sharing and patience are key. So I'm hoping to have the same level of success with the yuzu tree.

At this point I've read through Frank and others' posts (on this forum and others) regarding things to do help in-ground citrus survive (and even thrive) through long, cold zone 5-7 winters and am hoping to come up with a solid plan. Here's the outline of what I currently plan on doing, but I would *greatly* appreciate some feedback and clarification on a handful of points. I'm of the mind that it's always better to have more information and options when going into a new endeavor, rather than assuming and finding out later (after losing time, money and the lives of creatures I've assumed responsibility for) that I was willfully ignorant. Of course, I appreciate that there is no "one right way" of doing something and definitely admit to tweaking my own designs as experience dictates necessary, so I welcome all and any answers and solutions. And above all, I thank you all for your time spent reading and replying!!!

My plan thus far:

1) A 2 - 3" layer of pine bark mulch going out 3 feet from the tree.

2) A temporary greenhouse using PVC for the frame (with plenty of space around the tree), draped with plastic sheeting (that is secured with bungees or clips to the PVC) that extends to the ground where it will be held down with 4x4s.

3) Blankets and a plastic tarp to completely cover the enclosure for when winter sets in.

4) A 5 gallon bucket (leftover aquarium salt bucket) with an automatic, submersible thermometer (so it can sit on the bottom).

5) A wireless thermostat.

6) Heating cable for the roots?


Recommendation requests:

1) Any recommendations for the shape of the PVC frame? I was thinking about making a tall cylinder, slightly narrower at the top so snow wouldn't accumulate too much.

2) Any recommendations for the plastic cover? (i.e. what mil to use 3 or 6, how many layers to use)

3) Any recommendations for the type of blanket to use?

4) Any recommendations for a decent (frugal) wireless thermostat?

5) Any recommendations for a heating cable?


Application questions - mainly directed at Frank, but if others have suggestions I'm all ears!:

1) How heavily are you mulching your trees? Should I consider digging deeper around the tree and mulching deeper? Will too much mulch hurt the roots?

2) Would you recommend (or advise against) adding insulation in the ground around the tree, like styrofoam? If recommended, what type would you recommend?

3) I'm assuming the enclosure with plastic are added first in fall and removed last in spring, with the tarp & blanket added last (in winter) and removed first (in spring). How do you determine it's a good time to start covering with plastic (and then later with blankets and tarp)? First/last frost or daily low/high temps?

4) Is evaporation a problem with the "bucket of water" approach? I'll only be protecting one tree, but do want to make sure I don't provide too small an amount to be effective (and I know how quickly water evaporates in the winter out of my aquariums, particularly my larger freshwater tank). If a 5 gallon bucket isn't going to cut it, I can look into something larger (but hopefully small enough to fit under the one-tree enclosure).

5) Do you mount the sensor for the wireless thermometer at the bottom or towards the top? Are you using any sensors to measure ground temperature?

6) For the heating cable, I read that if you could start over you would bury them 1 foot deep 4 foot by 4 foot around the tree(s). Do you have this on a thermostat or does it have a built-in thermostat (if so, at what setting?) or are they constantly on during the winter? If the latter, at what point do you turn them on?

7) Would it be prudent to add a "light bulb" on an automatic outdoor thermostat, or would this be unnecessary (or possibly unwise due to possibly breaking dormancy during the winter)? I say "light bulb", as if I use this I would most likely try using a ceramic heating "bulb" like what is used in terrariums to avoid any potential dormancy or broken glass issues.

I also plan on keeping this yuzu tree smaller (say 6' maximum), but am wondering when the best time would be to prune it (considering it will be covered a good deal of the time)?

Again, I apologize for the flurry of questions - I have read a lot and at this point have more questions than answers. Thanks very much for reading this far and for any recommendations and suggestions! I will be sure to let everyone know how this develops.

John

I am tempted to say just keep it in a container and save yourself the hassle.

But...a challenge is just that. Frank has great results, so simply do what he does. You could also read up on what some of us do to protect palms in colder climates.

If the Yuzu is not going to exceed 6 ft, get yourself one of those small greenhouses that fold up for storage. I used one by Flowerhouse for a palm until the palm outgrew it.

For heat, you can use Christmas lights (C9) or a 100W incandescent bulb or two. Get yourself a Thermocube which will turn the lights on and off according ot the temperature.

The only problem with a greenhouse or similiar is that you have to open the flaps during the day when the sun is shining lest your tree cook in the heat and you end up with Yuzu stew.

It is doable. Go for it.

JackLord - Thanks for the suggestions!

My main concern with the christmas lights / light bulb approach is that (unless I'm missing something) it's not going to protect the roots. If covering the tree and mulching well will keep the ground temperature warm enough to prevent killing the roots, that would be great - I'm just trying to find some confirmation. Any thoughts on this?

I've read a lot of conflicting info on keeping the ground/roots warm during the winter. Some sources I've read say this will promote root rot, pest infestations and potential dormancy issues. Of course, I'm also concerned about a hard freeze killing the roots. Have you run into any of these issues?

I understand what you mean by cooking the tree, but in the dead of a typical winter (not what we had last year) I would imagine that the extended freezing temperature would be the greater issue. Honestly, I'd love to get a little greenhouse with an automatic vent for when the temps start rising, but if I can do this on the frugal side (as Frank's approach appears to be) that would be ideal. At the same time, I'd rather err on the side of caution rather than killing the tree (with too much heat or cold) because I skipped out on something I had plenty of time to setup.

That being said, if someone with yuzu experience near zone 6 can say "they're tough buggers, keep them covered so they don't get burned by the wind, keep them heavily muched and do the light bulb /auto thermostat setup and it should be fine", that would definitely be reassuring.

John

I protect my palm roots with lots of mulch. Now, that might be detrimental to citrus. You could use buried heating cables. Somebody else should chime in on the roots issue.

Just do exactly what Frank does. I have two kinds of hardy citrus in-ground in my yard. I do not protect them, but it has only been one mild winter, so the jury is still out.

After researching burying heating cables a bit tonight, I just thought of a way to possibly kill two birds with stone. Rather then keeping a bucket above ground, I'm thinking of burying four 5 gallon buckets (they are 18 inch tall "leftover" aquarium salt buckets - I keep everything...) about 2 - 3 feet out from the tree (think N, S, E, W) so the tops are an inch or two above the ground. In the winter I would fill them with water and throw an aquarium heater in each, building a circular PVC enclosure (temporary greenhouse) that would have them well inside. In the spring, I would just put the tops on and cover with mulch so they are neither an eyesore nor a potential hazard to my kids (don't need to create any inadvertent death traps in the yard!).

The idea here would be to both help keep the soil a bit warmer in winter, while also helping to keep the inside of the enclosure warmer. It would require four aquarium heaters, unless I can get creative with PVC and caulk to run a couple of pipes from bucket to bucket in a sort of underground ring structure. The benefit there would be only needing to use one aquarium heater, less risk of all of the water evaporating (since the total would be 20+ gallons including the pipes) and only needing to fill one bucket (as they would all be connected), but the risk would be one of the PVC pipes coming loose underground (or the connection to one of the buckets cracking) if anyone walks over the ground where they are located. If they are connected, I also wouldn't be able to just pull them straight out if necessary, so that's something else to consider.

Has anyone else used such a setup before? Any feedback would be great!

Thanks!

John

Following up from the last post, the idea would be something similar to this:

http://www.backyardchickens.com/a/harleenas-laundry-bucket-waterer

but with two PVC pipes connecting on each side of the bucket (one lower ring and one higher ring) kind of like this (please excuse the primitive ASCII...):

---bucket1---bucket2---- etc

------|__|------|__|-------
------|__|------|__|------- etc, with two more buckets in a circular loop.

I'll probably need to build this above ground and make sure everything is water-tight first before burying it around the tree, but that's the idea anyways. Kind of like a mini-geothermal setup, but with the tops open on the buckets for heating the inside of the enclosure.

On that note, another potential issue would be roots trying to grow into this setup, so I'll have to ensure that everything is solid. Maybe water tight grommets like these would help towards that end?

http://www.hydroasis.com/hy/productdetail.aspx?id=209

Any ideas?

John

After giving this a bit more thought, another important part of this setup would be to keep the water circulating through the buckets to ensure that the furthest bucket's water (or the water in the PVC pipes) doesn't freeze, so some sort of pump attached to one of the heated bucket's connected PVC pipes to move water to the other buckets would probably be a good move. Probably something like this would work fine, running a tube from the pump to the furthest bucket to ensure the best temperature dispersion:

Marineland NJ1100 Maxi-Jet Submersible Utility Pump, 21-Watt, 294 GPH
http://www.amazon.com/Marineland-NJ1100-Maxi-Jet-Submersible-Utility/dp/B0019IQKJW/ref=sr_1_11?ie=UTF8&qid=1336564918&sr=8-11

John

Hi John

I protect palms, Wollemi pine, fig..........in Massachusetts. I'd say the biggest 'issues' in winter protection is getting too hot inside the protection and too much condensation in the protection. You'll want your citrus to go dormant and stay dormant unless you keep temps very warm every day. I don't think you'll want open water containers in your protection......make sure the containers are sealed off. Perhaps getting a Yuzu grafted onto Poncirus rootstock will be a solution since Poncirus is fully hardy here without any protection. I'd do what Frank does since it works.

PS, critters get into protection too since it's warmer. Watch out for them too.

Four hours of summer sun is fine for Yuzu. Plant the tree where it has more shelter.

Tim - Thanks for the tips! I'll definitely cover the buckets to prevent evaporation and condensation, and keep the heater and pump sealed inside. I'm also considering just using two buckets with three PVC pipes connecting them in a loop about three feet out from the tree. Since evaporation won't be an issue, I can probably get away with a smaller volume of water. The reason I'm still interested in taking this approach to keep the ground around the tree from freezing is because Frank said that he ran into issues with the roots growing into the heating cables and damaging them. I wouldn't imagine the same issue would occur with the roots growing around the PVC pipes or buckets, although I do need to make sure all the connections and joints are solid so nothing leaks (which would promote root growth into those cracks). I figure popping the tops off of the buckets in the spring and the fall to check the water level would be sufficient to make sure everything is holding tight.

As for overheating, do you have any suggestions beyond using a thermometer to monitor soil and air temps inside the enclosure? More specifically, if temps inside the enclosure do get too high during winter (above 60 degrees?) would venting the enclosure at the top be the way to go, or would this introduce too much frigid air? I would assume covering with a blanket and tarp (as Frank does) would help reflect some of the heat from the winter sun, but I don't have any experience with this and have not had much luck finding specifics.

For rodent protection, I was planning on putting a barrier around the trunk and burying it a bit, as I've read is recommended. Are there any other steps I could take (short of setting traps inside the enclosure)?

As for doing exactly what Frank does, while I do admire and have learned from everything he has done, I believe there is always room for improvement. If the bucket and pipes approach works without the issues encountered with heating cables, I believe that would be time well spent (and possibly another option for others looking to grow citrus in colder environs). Believe me when I say that I enjoy a good experiment, I just want to get as much feedback as possible so I don't miss something "obvious" the first time around (like excessive condensation). Frank obviously researched a lot before trying his setup, and that's all I'm trying to do now.

Keith - I appreciate your advice, but have found that other fruit trees in the "4 hours of sun per day" area just don't grow or produce much. I don't mind taking some extra steps if it means I'll end up with a more vigorous tree that produces well. The yuzu will be my first attempt at citrus and anything that requires more drastic winter protection, but I do have experience with other fruit trees (fig, persimmon, Asian pear, pawpaw). Building an enclosure and using the buckets and pipes to warm the soil are my attempts at providing more protection.

Thanks again for your help!

John

I used a greenhouse enclosure to protect a Pindo palm here in Zone 7A. If the sun was shining at all, it was pretty much imperative to open up the vents as the inside temp would soar.

Of course, come sundown, the opposite happens. That is where the 100w bulb and Thermocube come into play.

I would check the weather each morning, open up the vent before work, and close it as soon as I arrived home.

PITA, but it worked. Indeed it worked so well that the Pindo not only outgrew the greenhouse, but also is now taller than I and I am 6'3". Not bad for a 1.5 foot speciment growing out of zone for 3 years.

These out of zone growing activiites can be very hands-on. We can always wrap it up in burlap and leaves and forget about it until Spring. But with a Yuzu, fruit production would become an issue.

I don't protect citrus up here in Mass..........I only have a Poncirus trifoliata outside which receives NO protection so I think other people can help you better with citrus.

I do have a Washingtonia filifera (less hardy than Yuzu) and I basically drove 4 stakes into the ground and wrapped the side with poly. I placed a string of Christmas lights inside with some dry leaves. I left the top open and the lights 'on' most of the winter. The Washy did fine and remained mostly green except for the upper most leaves. I placed about 8" depth of leaves around the perimeter for frost protection. This is not a super warm microclimate area either. Here's a photo:




Here's my larger protection with palms, fig and Wollemi Pine inside:

JackLord & Tim MA z6 - Thank you both very much for sharing your winter routines, that's exactly the kind of information I've been looking for!
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JackLord - Do you monitor the temperature of your enclosure? If so, what kind of temperature is typical for a sunny (but freezing) winter day when the enclosure is vented? If the forecast is cloudy, do you leave things closed up? Is there a certain temperature point that you decide to leave it vented vs closed (regardless of sun)?

That's quite the growth on your palm! Now that it's outgrown your greenhouse, how do you manage it? A larger greenhouse or a homegrown enclosure?

Good point that keeping the yuzu in darkness all winter probably isn't the best approach if fruit is a goal, since this is typically when it fruits (or matures, at least).
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Tim MA z6 - It's very reassuring to see your Washingtonia filifera setup mid-winter. Do you monitor the temperature for it, or do you just let it work itself out by leaving the top open with the leaves and lights for insulation and heat? Do you close up the top on cloudy or especially frigid days? If so, at what temperature do you make that decision?

I see there's snow on the top in the Washingtonia filifera pic. Is everything closed up in this picture or is it still open at the top? I'm assuming open, since the sun is shining, but curious about whether the snow would cause any damage. I have read that snow acts as an insulator, but curious as to any effect this has on leaves and/or venting (of course, it could always melt...).

The snow in your pics is pretty typical of what I get around here, and it usually sticks around for a while. During winter it's mainly overcast here, and we go weeks at a time without seeing the sun most winters (drives my wife crazy), which is why I am a bit concerned about just relying on sunlight for maintaining enclosure temps.
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Update - Well, I discussed my soil warming plan with my wife and she was less than supportive of the idea. As it turns out, her family uses the same approach (underground pipes with moving, heated water) to make conditions right for growing strawberries (in very large greenhouses) during the winter in Japan (they are professional strawberry farmers, and have been for many, many generations) and she said doing that for one tree it would be absolute overkill. She's probably right and (as usual) has brought me back to earth - significant others are good for that, aren't they?

Her suggested approach is to make a double-layer enclosure (without a blanket or tarp) and to cover the ground inside the enclosure (i.e. the mulch bed around the tree) with black plastic sheeting. Her family does this for their strawberries and the black plastic is very efficient at absorbing the sunlight, trapping the heat, and keeping the ground and enclosure warm , even on cloudy days.

I'll still probably look into a thermocube and lightbulb/christmas lights combo for overcast or espeically frigid days/nights, as well as some type of wireless thermometer, but otherwise it looks like my previous plan has fallen through. I'll be happy as long as the tree makes it, and at least I have something else to try next time around it not. If anyone else is adventurous enough to give it a try, please let me know if it works (and if not, why not).
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Thanks again for all the ideas, answers and for sharing your routines!

John

I am originally from Pittsburgh, the Churchill area. I can remember some very cold winters up there. Good luck on your endeavors. I am sure you will be the talk of the town with your citrus.