Take a tree from the landscape as soon as you can see budswell in the spring. I'm sure it would appreciate the gritty mix. All of mine do.

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Al

I thought I will pipe in anyway.

I do not know whether this will help you. I have baby (2 yrs) jap maples, some in the ground outside and some in pots inside a cold frame. The ones outside have not shown any bud swell yet. The ones inside the cold frame are ready to burst. I will repot the ones in the cold frame in the next few days whereas I will wait for the ones in the ground. I am in zone 6b but this winter has been unusually warm.

I would get the mix and the pots ready. Easier said because I am not really ready myself. Sometimes I feel that the cold frame creates more problems for me by speeding things up.

Thank you Al
and Thank you tropic...
I'll will watch my little tree and pot it as per your advice. Have the mix & the pot ready.

Rina

Al

Do you overwinter your bonsai in the garage? Which potted bonzai or pre-bonsai plants can you overwinter outside if any?
I would think that with much smaller pots & less soil one has to be more careful?
How much light do they get in the garage?
Your maple grove(?) is beautiful.

Tropicofcancer

I have question about the pots you are overwintering in cold frame. Is it necessary to give them any water during the winter especially if there is very little snow? I remember reading that Al puts some snow on his pots in garage. How about the ventilation on sunny days - do you open them a bit or are they "motorized"?
Maybe I am asking very basic questions, but I have no experience with cold frames. Did read some on the subject, would appreciate a first-hand experience with the trees/shrubs.

Anyone else - please share your experience, especially if in - but not exclusive to - "colder" zones (5-6).

Thnx.
Rina

My cold frame is big (at least to my standards). It is more like a small but unheated greenhouse. It is 7ft by 9ft with 4mil plastic and it is north side of the house in the yard. Most of the winter the Sun is so low that the house casts a shadow on it. In spring when a bit of sunlight starts reaching it I keep the two sides a bit open to keep it cool. In fact I keep two sides open if I know that the temp is not going to drop below say 25 and is not much windy. The two sides have zippered entry that is about 6ft long. Air flows through the cold frame. When expecting a storm I close them otherwise wind can lift it off the ground.

In winter I shovel bunch of snow in there from time to time. However, this year we barely got any snow. All the pots in there are still wet. I do not water till may be April and that too is rarely needed. The smaller pots may dry out quicker especially if they break dormancy. Snow is a great insulator and it is always better to cover the plants in snow.

In late March through April I have to be careful because temperature can fluctuate a lot. Since the plants in there break dormancy a bit earlier a sudden freeze can destroy some of them.

Another crucial bit is that my cold frame is sitting on a 1 foot deep mulch pile. I bury my pots in this mulch either fully or partially late fall. Some that are still baby plants stay like that buried in mulch through the summer also. This reduces watering requirement a lot and the plants fatten up quicker. In fact last summer I watered them may be less than 10 times. The rain took care of the rest. The downside is these plants will tend to send a big fat root into the mulch and the dirt below. Got to cut those roots before the pot becomes completely anchored to the ground.

Having said all that I do overwinter in the garage too because I need more space. I usually put the conifers there. A lot of folks do this for all their plants.

The third method I use is to leave them in my vege patch and cover them with leaf mulch up to the height of the pots. I use my blower/mulcher to suck up the dry leaves and dump them in my small vege patch and place the pots in there. Does well for bigger pots and my cedar box plantings. In spring all those leaves go to my compost pile.

Although I am zone 6b keep in mind that I am in urban setting and houses are close together. It is slightly warmer and less windy than open spaces.

I hope I provided you with some food for thought. I am not by any means an expert so feel free to doubt some of statements.

TOC,

That sounds like an interesting setup...any chance you could post pictures of your cold frame? I'd love to see it. Also was wondering, during the winter when it's in shade and all closed up, is the air temp. inside any warmer than the air temp. outside (neglecting wind chill of course)? What part of the country are you located in?

Alex

I have never really measured it properly. It always feels a tad warmer than outside. If outside temperatures are steady in the night then eventually the inside temperature will reach the same or close to it. It probably lags the outside temp drop to certain extent.

Today it is already 60 here and I have to keep it fairly open. I will take some pics today and post later with some more info.

Rina - I over-winter almost all of my temperate plants in the garage. I leave a few larches and pines on the bench outdoors, and a few large yews on the ground. Everything else is on tables in the garage. Considering only temperature, you can generally over-winter anything hardy to 2 zones colder in pots w/o protection. By burying the pots in the garden you can over-winter plants hardy in the landscape; and you can usually pick up a zone if you bury the pot against the north foundation of a heated building.

Dormant deciduous and resting evergreens don't need any light to make it through the winter. I have friends that over-winter their bonsai in large pits with all light excluded - no problems.

All the best to you! ;-)

Al

TOC -
big thank you for detailed description...sounds like a great cold frame to me too, and I am looking forward to see photos if you post them.

Al -
thank you for the answer. I did read long time ago about bonzai in the "pit" for the winter, you just reminded me.
I keep lots of plants in pots & just leave them outside, all together in one area, and dump shreded leaves around as mulch. Since they were potted in regular soil, many retain too much water-considering that, I have pretty good survival rate! I am so glad that I came across your posts about fast soils...everything is eventually going to be repotted in gritty mix.

Rina

It made all the difference in the world to me when I first got into bonsai. I couldn't keep ANYTHING in shallow pots alive because of the significant PWT associated with peat-based soils. Once I finally figured things out & found the ingredients & how to put them together for the gritty mix, it was smooth sailing from there on. It just doesn't get any easier than the gritty mix & FP ..... unless you're a Chia-Pet freak. ;-)

Al

I finally got around taking some pics of my cold frame yesterday. Here it goes.

The first pic is of the entire structure. It is made using 1 inch electrical conduits and canopy parts. It is covered in regular 4mil plastic. I doubled the plastic for strength for snow loads. It is held to the frame using spring clamps. On the ground they are held by 4x4 pressure treated lumber or garden lumber. It also keeps the plastic taut. The plastic is in 3 pieces - 2 for the ends and one big that wraps the long sides and the top. I take it down every spring and put it back in fall. It takes about half hour for two of us to do that. This has survived 12 years now. The plastic needs to be changed every 3 years or so.

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Here is a close up of the door/entrance at the peak. You can see the zipper that ends at the top.

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The entrance plastic is installed first and held to the frame inside using ropes and tarp clips. The top sheet is put last and held to frame using the spring clamps. To protect the plastic I just fold up old plastic pieces several times and then put the clamps.

Here is an inside view with the bed of mulch. Most of the plants are quite young less than 4 years old. There are a few older "mother" plants for taking cuttings.

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A close up of the peak from inside.

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Hope that was helpful. As Al said light is not needed so a garage or shed is also a perfect place. I use this mainly for baby plants and some that are marginally hardy like Nandina, some varieties of jasmine, etc. Sometimes when I am not sure, I use this as an insurance against killing a potted plant outside. I also use this to double as early start with veges that are sprouted inside the house and then hardened off in the cold frame.

Also note that do not bury ceramic or clay pots. They will crack pretty quick.

I am way off the topic of this thread.

Thanks for posting these pictures, TOC. Your cold frame looks for all the world like a greenhouse to me, albeit a portable one. That's great that you're able to assemble/disassemble it so easily.

The raised beds in the first picture - are those the mulch beds where you bury containers in during the spring/summer/fall?

Sorry Rina for diverting your thread...

The canopy parts makes it easy to (dis)assemble them. It can be done by one person but two makes it a lot easier. I know it is lot like a greenhouse but to me it is like a little zone 8.

Those raise beds are also largely mulch beds where I partially bury some of the tropicals in summer and in winter I partially bury the temperate/conifers. That way I have a very flexible landscape. The buried pots look like part of the garden - sort of. Rain takes care of most of the watering but sometime a tiny pot may dry out completely and the plant will die because it is tucked away under some bigger plant. There are always some casualties. Last year I lost a dwarf fuschia and I did not take any cuttings in time.

Inside the cold frame, the bed is also mulch. I sort of mix shredded and bark mulch depending on what is at hand. I have built them over the years. Below six inches or so the mulch is practically decomposed sticky dirt. I replenish these beds every year and dig it up a bit to loosen it. Sometimes I will add some spent mix from containers with lots of grit and turface in it. In fact my entire garden now has some grit/turface/gravel/topsoil/compost in some random proportion. I try not to disturb too much at a time to keep the eco system going.

Thank you Al,
appreciate you taking time to answer.

TOC, great photos, thank you for sharing. Being sort of greenhouse, it is easier to get to your pots if needed, right? And as you said, double duty for hardening-off.

Maple grove, no problem, ask anything...

Rina

Rina, I always thought of it as a cold frame. Now that two of you mentioned it is sort of a greenhouse I have to mull over it. Really I did not want to crawl around to find a place for my plants. I am also contemplating some sort of plant shelf there for my ever increasing number of experimental plants.

In spring it is a pain since a little bit of sunlight can raise the temperature considerably. I am thinking of trying a shade cover next time.

My first attempt was using PVC tubes - small hoop house. The tubes became brittle and split one snowy winter. After that it looked like a dinosaur carcass. The plants were fine except a few broken branches and such.

TOC
I am glad that you mentioned about hoop house/PVC tubes. I was thinking of setting one that way - so I think I'll pass on that. I am very seriously considering raised beds build from blocks; it will be tidier, easier to work since I am getting older...but some expense & lots of work to set up. I would like to have at least some of them covered for the winter.
I think shelving is a great idea.
Would you leave just shade cloth over the winter?
I have lots of shrubs from seedlings & cuttings. So far no trees, but would like to. Do you grow your trees from cuttings?
All my other pots have to go inside for the winter, will not survive in the garage. Rina

Rina, Some swear by PVC tubes. I used 1/2inch tubes so they curve easily. But if the curve is too tight they snap also easily. Some people had more success with fatter tubes. I have seen articles and pictures of those.

I have raised beds with blocks too. 8x8x16 blocks and even they shift a bit every freeze/thaw cycle. I just dry stack them though. I also fill them with soil and plant random flowers/creepers in the holes.

It would be a cool idea to build a low cold frame on top with a lid of sorts. Like traditional cold frame style but on a raised bed . That should work well. The slope of the top needs to be steep enough shed the snow load though. Plain wood frame should work well too. Make sure it is not too big to reach all parts of it with your arms.

My greenhouse/cold-frame is shaded through early March. After that it increasing amounts of sun. Today I would have built it closer to the house so that it would be shaded longer. I think I need the shade cloth for early March onwards but it could be left all winter. After all the plants really do not need the light.

Most of plants are from cuttings and air layers. Some are from seed. In spring I scout around the neighborhood and the cemetery for seedlings under maples, dogwood and other small trees. In fact, I have about a dozen of regular red maple seedlings collected this way. All of them are 2-3 years old now. Initially I lost a few in the first year though.

I make a lot of cuttings every now and then. This year I am into cuttings. In fact, I already started on some inside the house. A few dwarf chinese elms and they look good so far.