Chill hours

GrimLore

Bonsai Nut alumnus... we miss you
Messages
8,502
Reaction score
7,452
Location
South East PA
USDA Zone
6b
when trying to calculate or gage chill hours for trees, is it continuous hours below 45F or any hour below counts?

Don't think into it so detailed - it will make you crazy for no reason...

A good general rule of thumb to follow goes like this -

Plant Spring bare rooted that are suited to your zone in early Spring.

Plant dormant bagged or potted trees suited to your zone in the Fall.

They should acclimate properly if healthy and just plain do good with normal care ;)

Tropicals and Subtropical Plants are a bit different but most do need some down time too, just not anywhere near as much. That could be a whole other thread here, honest :p

Grimmy
 

miker

Chumono
Messages
726
Reaction score
688
Location
Wyomissing, PA
USDA Zone
6b
Just wondering what you will do with this information once you have it.....?

I ask because just reading that post is unsettling.
Seems a lot of worry about something we can't, or shouldn't, change, or try to "play God" with.

I've never done anything special for winter, mostly because I couldn't.
Until this spring I never had anything wake up early.

I messed with them and they died.
Lesson learned.

If something wakes up early.....

Just dont do anything.
Don't move it, don't repot it, don't worry about it.....

Ooooooooeeeeewww......

Forgive me but this "as the buds swell" BS.

My buds on these (Amur/Ulmus) started swelling in February....
For near 2.5 months they stayed like that through further freezes and thaws until they knew it was time to wake up, when they continued growth.

I am certain had I just left them alone they would be alive.

I am certain, seeing buds swelling, even opening a little, has caused people to move their trees into a different place, in hopes to try to "save" them..

This can work.

But fret not I say......

The tree is well equipped to know the weather.
More equipped than we are aware.

I view a setup like Judy's working.
Where everything is consistent.

My NFG system works. Cold froze don't care.

But this in-between.....

Inconsistent, garages, coldframes...etc....

Seems to make everything so much more difficult than it needs to be.

Of course........
Everyone enjoys bonsai differently.

Maybe some folks yearn to carry heavy shit and fret....

I'd rather be eating Xmas cookies!

Sorce

Sorce,

I don't view trying to alter the number of chill hours a plant/tree experiences (by special placement, refrigeration, etc.) as any different than protecting trees from cold/freezing temperatures or wintering tropical trees in a greenhouse or inside the house up north in the winter. Which is to say, if you are good with keeping your ficus in a solarium over the winter in Ohio, why not try to keep your JM and JWP in a situation that maximizes chill hours during the winter if you live in Texas or Georgia?
 

GrimLore

Bonsai Nut alumnus... we miss you
Messages
8,502
Reaction score
7,452
Location
South East PA
USDA Zone
6b
And of course... there is always citrus :)

Going by the way growers and Universities like Cornell have been working on it I find it amazing how many Fruits trees you can grow in colder zones then mine at present. I hope to see the reverse and Northern growers able to grow some citrus - perhaps in my life time.

Grimmy
 

sparklemotion

Shohin
Messages
490
Reaction score
800
Location
Minnesota
USDA Zone
4b
Sorce,

I don't view trying to alter the number of chill hours a plant/tree experiences (by special placement, refrigeration, etc.) as any different than protecting trees from cold/freezing temperatures or wintering tropical trees in a greenhouse or inside the house up north in the winter. Which is to say, if you are good with keeping your ficus in a solarium over the winter in Ohio, why not try to keep your JM and JWP in a situation that maximizes chill hours during the winter if you live in Texas or Georgia?

Moving plants indoors to an area that is kept artificially warm is a lot easier, logistically, than maintaining any artificially cool space.

As someone in Zone 4, I find tropicals much easier to care for than temperate trees that aren't hardy here. Because I can keep things warm, but cool (not too cool) is a lot harder, especially if you take light requirements into account).

I intend to take on this challenge to an extent next winter (as recent seed orders would attest), but I would definitely have preferred it if the JBP challenge were open to substitutions for cold hard trees. (to be clear I also intend to grow some more MN appropriate pines over the same duration, my FOMO just won't let me be content without having a contest entry).

But I know that I am signing up for unnecessary trouble. Sorce is saying that the trouble isn't worth it (and I kind of agree, for folks in zones with so many other great species options) .
 

rockm

Spuds Moyogi
Messages
14,181
Reaction score
22,179
Location
Fairfax Va.
USDA Zone
7
Sorce,

I don't view trying to alter the number of chill hours a plant/tree experiences (by special placement, refrigeration, etc.) as any different than protecting trees from cold/freezing temperatures or wintering tropical trees in a greenhouse or inside the house up north in the winter. Which is to say, if you are good with keeping your ficus in a solarium over the winter in Ohio, why not try to keep your JM and JWP in a situation that maximizes chill hours during the winter if you live in Texas or Georgia?

Well, err, because it's not good for the plants and can kill them. Ficus suffer when kept inside during the winter--they're not at all happy and get weak.

Trying to maintain cold temps in a hot environment presents it's own problems. The chillers you would have to use produce heat externally, additionally, they also tend to dry out the air, which makes humidifying it important. Both are expensive tech challenges that produce mostly uneven, sometimes dubious, results.
 

Dan92119

Mame
Messages
177
Reaction score
193
Location
San DIego CA
USDA Zone
10a
I can grow apples here in my zone. Golden Dorset, fuji and Anna. They produce fruit every year. If I would let them, they would produce two crops a year. I haven't been able to find out how many chill hours Crab apples need. I ordered a few Dwarf Japanese Flowering Crabs.
My peach, plum and apricot trees are starting to change color and drop their leaves. I tried taking air layers of my apricot tree, but they failed. Its a Gold Kist, its has nice sized leaves, nice fall color. Might make a nice bonsai.
This time of year we have a high temperature differential between day and night. 47 last night 82 today.
I am trying a few trees for bonsai that do well here, such as pomegranate, mulberry, Chinese elms and oaks.
 

Anthony

Imperial Masterpiece
Messages
6,290
Reaction score
8,388
Location
West Indies [ Caribbean ]
USDA Zone
13
Canada uses a refrigerator for maples.
Trinidad uses a refrigerator for maples [ or used to ]

Once the top temperature stays around 30 deg.c
A good many trees can cross over.
Just need to control the dormant temperature.
2 months for "winter'.
Good Day
Anthony

* And then the natives took over.
 

miker

Chumono
Messages
726
Reaction score
688
Location
Wyomissing, PA
USDA Zone
6b
The refrigerator worked well for me when growing a few temperate trees in Orlando for many (13) years. The only time I lost trees was when I let the soil get completely bone dry due to my negligence, as they are easy to forget in there when one gets busy. It may not be a perfect solution, but it got the job done for me. The temperature range, however, is pretty much perfect for the purpose. I never measured a temperature in my refrigerators lower than 31F or higher than 42F.
 

hemmy

Omono
Messages
1,390
Reaction score
1,717
Location
NE KS (formerly SoCal 10a)
USDA Zone
6a

I thought this would be a good spot for this link, if someone searches "chill hours". It is a neat website. But finding the weather stations to enter is a little bit of a trick. There is a link to a weather station map but it blue in text and the background makes it hard to see. This station example is the Oxnard, CA airport.
 

Attachments

  • 2022-10-20_01-18-20.jpg
    2022-10-20_01-18-20.jpg
    195 KB · Views: 3
Top Bottom