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stratifying in the fridge - any concerns?

Posted by hairmetal4ever Z7 MD (My Page) on
Sat, Nov 23, 13 at 9:57

I might stratify some tree seeds (acorns mostly, & some maples) in the refrigerator - I've heard that ethelyne from fruit in the fridge can kill embryos...is this true?

Are there safeguards I can take to ensure this doesn't happen?

Due to critters I'd prefer not to stratify outdoors.


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RE: stratifying in the fridge - any concerns?

  • Posted by morz8 Z8 Wa coast (My Page) on
    Sat, Nov 23, 13 at 11:16

"ethelyne from fruit in the fridge can kill embryos"...no, not a concern.

Put your seeds in a tiny zip lock with just a small amount of sterile moist sand or sterile moist vermiculite, date them. When the suggested number of weeks has passed, take them out and sow them.


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RE: stratifying in the fridge - any concerns?

Is "play sand" OK to use if I sterlize in the oven first? I'm just thinking that since I have 2 kids and a HUGE supply of that.


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RE: stratifying in the fridge - any concerns?

  • Posted by morz8 Z8 Wa coast (My Page) on
    Sat, Nov 23, 13 at 15:03

Yes, if that is the sand you have it will be fine but it must be clean, no bacteria or debris in it. Damp, not slurry wet in the bag.


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RE: stratifying in the fridge - any concerns?

OK - thanks. I'll bake it dry (it's wet from sitting outside) - then moisten it, maybe let it sit a day to drain/dry out a bit before doing it.

Another question - what do I do with acorns from the white oak group? They sprout right away, but I don't want them to - I don't have anything to do with them over winter (no grow lights, too little natural light in the house). They don't NEED stratification, but can I delay germination w/o them trying to sprout or die on me?


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RE: stratifying in the fridge - any concerns?

OK - red oak acorns (the whole group, Red, Scarlet, Pin, etc) - will they start sprouting roots when they're "done" stratifying? Or should I just go w/the suggested number of days and take them out? I've seen anything from 30 to 90 days stratification for just about all of them.


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RE: stratifying in the fridge - any concerns?

  • Posted by morz8 Z8 Wa coast (My Page) on
    Sat, Nov 30, 13 at 13:05

While some plants will begin to germinate while still at the colder temperatures, most will not until they brought back to warmer.

These are suggestions from the Clothiers site for different types oak and the information there is reliable. Understand that they are not the only method to encourage germination but methods that have been tried and have worked. You may be finding different stratification times as not all types oak are the same.

Where he is suggesting planting outdoors in Fall, it may be because a warmer period before the chill is helpful, and some seeds will respond better to fluctuating temps like those found outdoors (changing weather, day night differences etc).

Clothiers: Oak (w=week, M=month)

Quercus acutissima , Sawtooth oak ,zone= 5 , direct sow outdoors in the fall
Quercus alba , White Oak ,zone= 4 , direct sow outdoors in the fall
Quercus coccinea , Scarlet Oak ,zone=
4 , sow 3m @ 39ºF, move to 70ºF for germ. Quercus imbricaria , Shingle oak ,zone= 4 , direct sow outdoors in the fall
Quercus macrocarpa , Bur Oak ,zone= 3 , direct sow outdoors in the fall
Quercus palustris , Pin oak ,zone= 4 , direct sow outdoors in the fall
Quercus phellos , Willow Oak ,zone= 6 , sow 3m @ 70ºF, then 3m @ 39ºF, recycle
Quercus robur , English Oak ,zone= 6 , sow @ 70ºF
Quercus rubra , Red Oak ,zone= 3 , sow 6w @ 39ºF, move to 70ºF for germ.
Quercus virginiana , Live Oak ,zone= 7 , direct sow outdoors in the fall


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RE: stratifying in the fridge - any concerns?

Not all "sand" is made from silica. Most is, but I'd still check the bag or source documentation to be sure. Otherwise, pH could be a problem.


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RE: stratifying in the fridge - any concerns?

Is perlite OK? I have a bunch of that, but I'm concerned it won't hold enough moisture.


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RE: stratifying in the fridge - any concerns?

Hairmetal, oaks are not all that fussy to start. Even used tea bags will do for stratification medium. Damp soil, damp sand, damp dead leaves, used tea bags, damp peat moss. The big thing is just damp. Too wet and they may go mouldy, but just damp, you can use just about any media. Damp paper towels even....
I've been starting oaks for years for our woods, and it's pretty easy. If you have a good site, they'll grow fast . We cut some of the ones I planted to make saw logs to sell for money when the kids got married...nice logs too.

Jocelyn


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RE: stratifying in the fridge - any concerns?

Here's another question. I have some Yellow Buckeye (Aesculus flava) in the fridge in a perlite/peat mix I ended up settling on. Instead of a bag, I used a washed to-go container that soup from the Olive Garden came in - about the size of a typical soup bowl with a clear snap-on lid with a tiny hole in the middle. The small ziplocs were too small to hold more than a couple buckeyes and the freezer-size bags seemed overkill (per my wife).

A - would that be OK or will it dry out too much and/or possibly cause ethylene contamination?
B-if the tips of a few of the seeds stick a bit out of the peat/perlite is that OK or should they be completely covered?
C-one of the seeds has a slight crack in the coat on one side, near the "scar" end where it was attached to the tree, that looks like where a root would emerge - does that mean it's already germinating?


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RE: stratifying in the fridge - any concerns?

Aesculus is pretty easy too. You can try a damp paper towel in your take away container so they don't shrivel, or a used tea bag that has sat out to dry for a day so it's just damp. The crack near the blunt end can mean it is slightly damaged, not enough to worry, or that it wants to grow now. The sprout usually comes out the end opposite the attachment scar, but if the shell is thick, it will run around the inside of the shell till it finds a place it can break through.


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RE: stratifying in the fridge - any concerns?

OK - thanks! They all sunk except for one when I did the float test, so I'll venture to guess that one with the crack is probably OK. I threw out the floater after dissecting it (it was white inside, but hollowed out).


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RE: stratifying in the fridge - any concerns?

I tore a paper towel to fit the size of the container, wetted it, then wrung it out to where it is just moist - then gently pressed it on top of the seeds/peat mix. I'll just check occasionally to make sure it stays moist, and if it starts getting dry, maybe hit it with a couple sprays of water from a spray bottle.

Is much harm done if I occasionally dig around in there to check for any signs of root emergence? This would go for any seed I'm stratifying of course.


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RE: stratifying in the fridge - any concerns?

You can dig around gently, but the root tips are fragile and may break off, so careful. If they do break off, the seed will often send out new ones, but it will cost that seed energy..meaning a smaller seedling. There is also the risk of rot from a broken root, so don't dig too often or too much. You can start tipping the whole batch gently out on a plate to check for germination any time now. Some species will start about January, some wait till March. Pot whatever has germinated, return the rest to the fridge.


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RE: stratifying in the fridge - any concerns?

My concern about "dumping" like that, is that I've read that, at least for seeds that have Hypogeal germination, that the root starts "knowing" it's direction before emergence, and turning it over after that point can cause it and the emerging stem to make a curly-q and therefore a poor/useless plant.

I'm not sure what to "do" with them if they germinate too early - I can't really put them outside before around late March at the earliest, and my house has really nowhere with enough light that is safe from children, pets, etc. I do have some fluorescent lights. I suppose that could be a makeshift solution. Too bad I no longer have my MH HID light ballast & reflector.


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RE: stratifying in the fridge - any concerns?

Don't dump them unless you can pot them. Pot with the little white sprout in a hole made with a pencil in the soil and pinch the soil around it. They will hold for a while, once sprouted, but the end of the root will rot off if you hold them way too long. Check on them, and see if you can set up something alternate if any grow roots about an inch long or more. You will be Ok till that point...after an inch, they need to be potted. If grown under low light conditions, all is not lost. You can put the spindly little fellows out in a shady spot with no wind for a few hours once things warm up. Each day, give them a little longer in the shade till they have about 3 hours. After that, move them to less shade, stronger sun. They thicken up fast.


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RE: stratifying in the fridge - any concerns?

One of my buckeyes keeps getting a white fuzzy mold on it. It wipes right off, and the seed seems sound and not rotted.

Is it doomed? What fungicides or even home remedies could I try?


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RE: stratifying in the fridge - any concerns?

Wash it under the tap and repack the whole batch in new, drier, medium. The stratifying medium is contaminated with mould, so you need a new batch. use a little bleach and wash the container before putting all back in it.


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RE: stratifying in the fridge - any concerns?

OK - I did what you recommended and so far, no mold has returned. Fingers crossed.

However, the buckeyes, as well as some Scarlet Oaks, were shoved to the colder back part of the fridge by someone and I noticed today the mixture was partially frozen.

Will they be OK? I can't imagine the actual temperature, being in a refrigerator and not a freezer, was more than a couple degrees below freezing.


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RE: stratifying in the fridge - any concerns?

Nuts contain sugars that prevent freezing till about minus 6 (degrees C), not sure what that is in farenheight. Slight freezing of the stratifying medium is OK. Even american chestnut can take slight freezing, and they are tender. Chestnuts that the squirells hide in the Halifax, NS area come up in the spring if not eaten. Oaks come up in PEI, just north of Nova Scotia, when cached in the fall by squirrels. Even if the blunt end of the nut is eaten, the embryo end often is not, since that part is bitter. These partly eaten nuts come up too, they just make a smaller tree the first year. They resume normal growth after that.


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RE: stratifying in the fridge - any concerns?

-6C ~ 21F if my math is right, so I think we're good.

They should be fine - one of the buckeyes, the one I collected and started stratifying in October (the rest I purchased and didn't start in the fridge until December), had a big crack across it. I thought it had frozen and cracked, but noticed it's germinating - a root is coming out!

I found a place to put it in the house - will this "extended" growing season mess up it's normal dormancy cycle?


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RE: stratifying in the fridge - any concerns?

No, it should be OK. I start them whenever they sprout, and as they go outside when it's warmer, they harden off at the right time in the fall. Once in a while, if they get too dry, when I'm really busy and forget them, they enter summer dormancy from being too dry. They may not resume growth for the rest of the summer after that. They will, however, store up lots of reserves in the roots so growth the following spring is really fast. Keeping them moist but not sopping wet makes for maximum growth. If winters are long where you are and spring can be slow and cold, slow down watering in the fall, at least 4 weeks before frost is expected. This allows them to store enough reserves to make a long winter, rather than squandering carbohydrates on maximum growth...and running out before spring.


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RE: stratifying in the fridge - any concerns?

I've done this many times with various tree seeds without any problems. I have not tried it with acorns however. The squirrels in my area plant about 500 of them in my yard each fall and they come up everywhere in the spring.

For stratifying tree seeds I simply collect the seed and let them dry for a few weeks in a paper bag at room temperature. I then remove any wings or fruit coatings from the seed. Then I soak the seeds in a weak mix of hydrogen peroxide for a few hours to remove any residue and bacteria from the seed coats. I rinse the seeds in cool water and let them soak in sterile water overnight. I then place the damp seeds in plastic bags along with a small amount of damp (not soaking) sand. At that point I label the bags and place them in the fridge.

I've had good luck with this process in the past and never had any healthy, viable seeds rot or have any issues. Germination is typically quite good, although much depends on the quality and source of the seeds.

TYG


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RE: stratifying in the fridge - any concerns?

You'll notice several different ways of doing this. The good news is that they all work. Seeds are meant to grow. You have to keep them a little drier if using non sterile media, and surface sterilization with peroxide or bleach allows for more moisture without rot. It's all good. Bleach is one spoonfull of bleach to 4 of water...or one bucket to 4, depending on how many seeds you want to treat. Tender seeds could probably use only one to five dilution. I'm like the previous poster, the squirrels plant a lot of oaks and beech for me. Industrious little rascals.


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RE: stratifying in the fridge - any concerns?

The bleach doesn't damage the embryos?


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RE: stratifying in the fridge - any concerns?

No, at that dilution, it's fine. I've bought a lot of chestnuts treated with bleach and got good germination. Mind you, for my own seed, I don't treat, I just keep the medium a little drier.


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RE: stratifying in the fridge - any concerns?

I agree with jocelyn, there are many different ways to stratify seeds. I have tried using the "paper towel" method and that works as well. As long as the seeds are damp and cold for the necessary length of time without fungal problems you should be fine.

As mentioned, I typically use plain, ordinary damp sand for seed stratification but I've read that other people use things like peat, pine bark, coarse gravel, even cotton facial pads, in place of sand. As long as your stratification medium is just barely damp you should be OK.

I strongly suggest not use any kind of regular garden soil without sterilizing it. You have no idea what kinds of weed seeds and bacteria may be in that soil.

I've not used bleach to sterilize the seeds but as stated above it seems to work very well. I find that peroxide works well on seeds, and I have never had any fungal/mold problems when using it.

Thanks

TYG


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