How to care for Japanese maple seedlings?

stevation(z5a Utah)July 16, 2008

I have tried to raise several (maybe a dozen) seedlings from my large Japanese maple -- I dug them up from the bed by the tree and put them in little pots. But they keep dying. This is a plain red JM (Acer palmatum 'Atropurpureum').

I'm a pretty good gardener, but I'm not sure how to care for these little guys. I even sprouted nine of them from seeds last year (stratified them in the fridge and all), but I lost them over the winter (I may have waited too long to bring the little pots into the basement).

So, what's the secret to getting these seedlings to grow? Some have lived for months but never put on any growth. Some have grown a little and then died.

Do they like to be consistently moist or to dry a little between waterings? Should they be in complete shade or get a few hours of sun? Do they need humidity to do well (I live in a place with very dry air)? What do they need in terms of fertilizer?

I keep them on my covered deck in the backyard, and they only get a little morning sun. I water them every two days or sometimes every day if it's really hot outside. Once in a while they've gotten Miracle-Gro at half strength. Any ideas what I'm doing wrong?

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This info is from a previous thread:

Propagating Japanese Maples

Japanese Maple seeds are ready to be picked when they turn brown and start falling from the tree (around Sept through Nov - depending on your zone). Collect the seeds and clean them by breaking off the wing attached to the seeds. Place the cleaned seeds in a cup, and fill the cup with hot tap water and let them soak for 24 hours. This will soften the outer coating of the seed so moisture can penetrate and germination can begin.

After soaking the seeds place them in a plastic bag in a mixture of moist peat moss. Make sure the peat is moist but not too wet, you donÂt want the seeds to rot. The bag should be closed but not completely air tight. Poke a few holes in the bag.

Store them at room temperature, but not in direct sunlight for a period of 90 days, and then move them to the refrigerator for a period of 70 days. During the cold stratification period check your seeds once a week to see if any of them have begun to sprout. Once they sprouted, plant them in soil at 1/8" deep. Make sure you donÂt plant them too deep, and keep them watered but not too wet. Once they begin to grow provide them with about 50% shade. That's all there is to it.

    Bookmark   July 16, 2008 at 6:03PM
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stevation(z5a Utah)

Yeah, I got them to sprout OK, it's the care during their first year that is turning out to be a problem. And all I get from that post above is they should have 50% shade.

Anyone else out there actually have experience growing some JM seedlings? What do you do? Where do you put them, how much do you water them, how do you fertilize them, etc?

    Bookmark   July 17, 2008 at 1:18PM
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flowerfan2(z8/ WA)

I have been growing seedlings for about 4 years. They do have a high mortality rate. I loose a lot of them. Weevils and slugs girdle the stems, and they get rot. You need to pot them in very porous well drained potting soil. I use a lot of crushed beauty bark and potting soil. I live in the cool PNW so the seedlings can take full sun for me. I have found miracle grow is too alkaline. My seedlings develope chlorosis using only Miracle grow. I added some acidifier to it and that helped. The growth rate is so variable depending on the type of maple. Some will grow a few inches a year and some a foot. I usually fertilize them in March or April a couple of times, and then again in July when they have another growth spurt. I usually grow them in a 4 inch pot the first year and then in late winter or early spring when they are dormant I pot them up to a gallon pot. I water the 4 inch pots in full sun almost every day. The 1 gallon pots that might be in half sun, maybe 2 times a week. It's a lot of trial and error. I would try giving them more sun in the morning maybe 6 hours or so and see if that helps. Here are a few of mine.


    Bookmark   July 18, 2008 at 1:31AM
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stevation(z5a Utah)

Karen -- thank you! I've been wondering if maybe too much water has given them some kind of rot. I'll try a more porous soil mixture and more sun, and I'll get a different fertilizer. There used to be a version called Miracid that was for acid-loving plants. I think it's now just called Miracle-Gro for Azaleas or something like that. Maybe I can find that or some other fertilizer meant for the acid-loving plants.

Thanks again.

    Bookmark   July 18, 2008 at 1:07PM
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You might try some of the Osmocote type fertilizers as well. I buy JM grafts all the time and the pots are full of it. Also, there are some systemic fungicides that should help with root rot and other curses.

Karen, have you tried copper wire for the slugs? Wrap a piece of bare (not coated) copper wire around the middle of each pot. Evidently the electrical properties of the copper don't set well with slugs! When they touch it, they backoff!


    Bookmark   July 18, 2008 at 8:56PM
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According to "Kaitain7"
"After soaking the seeds place them in a plastic bag in a mixture of moist peat moss. Make sure the peat is moist but not too wet, you donâÂÂt want the seeds to rot. The bag should be closed but not completely air tight. Poke a few holes in the bag. Store them at room temperature, but not in direct sunlight for a period of 90 days, and then move them to the refrigerator for a period of 70 days. During the cold stratification period check your seeds once a week to see if any of them have begun to sprout."

Here is my question:
I just gathered the seeds from a local botanic garden grounds.
quest#1: how many seedlings should I put/plastic baggie?
quest#2: how much peat moss/baggie
quest#3: if I bag the seed(s) at room temp. for 90 days, that brings me to March 1st '09. To then stratify them in the refrig. for another 70 days brings me to about the 1st week in May '09. Is that too late to be bringing the seedlings out of "cold storage?" Should I just place them in the refrigerator now for 90 days then transplant any that germinate to small pots indoors?
Please advise. Thanks

    Bookmark   December 1, 2008 at 12:11PM
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lou_midlothian_tx(z8 DFW, Tx)

The easiest way to germinate JM seeds that I've found is to soak the seeds for 24 hours then place them on moist paper towel in a sandwich plastic container with the lid on. Put the container in the fridge. Depending on the species, the period of time varies in the fridge before they start to germinate then you can simply place seeds in 50/50 perlite and peat moss mix at room temperature till they are a couple inches then place them outside (that's what I use in Rootmaker starter tray) then 3 parts pine bark fines, one part expanded shale and 1 part peat moss for 1g or larger when they are ready to be potted up. Green JM seeds took a few weeks to germinate in the fridge. Shantung maple seeds took the least amount of time to germinate. Red JM takes 2-3 months. Trident maple takes around 2 months. This is based on Deno's work. I much prefer this. A lot less messy and reduce space as well.

If you somehow get your hands on Micromax and Osmocote 18-6-12 (9 months) and 17-7-12 (12 months), you get better growth. It's tough to get them because I'm not "commerical" grower. I use Dynamite 18-6-8 (9 months) from Lowes or Home Depot which seemed to do decent job.

    Bookmark   December 2, 2008 at 8:29AM
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I transplant my JM seedlings outside in early to mid-summer in a nursery bed, placing the seedlings about 6" apart. In late fall, I mulch the bed heavily with oak leaves (several inches) which I hold down with plastic netting, and uncover them in early April the following spring. Depending on their parentage, I get anywhere from 50-90% survival. I live in zone 4 Minnesota so am pretty happy even with a 50% rate. I transplant the survivors later on that year if they are 1' or more in height, those that are shorter get mulched for a second winter and then are transplanted to their permanent location the following spring/summer.

    Bookmark   December 17, 2008 at 11:59PM
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stevation(z5a Utah)

Thanks for the tips, kms4me. How much water are they getting in that bed -- how frequent? And are you applying any fertilizer?

I think this sounds like a good idea for me, too. I did have two other tree seedlings in pots, plus two clematis I grew from cuttings, that I decided to put in a section of my veggie garden this year. That gave them better watering and protection from the heat drying them out in the little pots. With the clematis, I just buried their pots, since I read that their roots like to get a bit crowded, but with the trees, I planted them in the bed.

Do you do any root pruning before you dig them up? If so, how long before you dig them up?

    Bookmark   December 18, 2008 at 10:58AM
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I water them in with a low dose of water-soluble fertilizer or fish emulsion when I plant them. I don't feed them after that as I don't want to encourage too much growth later in the season that won't have any chance of hardening off.

Rainfall is usually pretty regular here so I water them only if there is extreme drought. As long as there is no leaf scorch or drop, I leave them alone. I think it results in less but stronger growth.

I don't root prune my JMs. I try to move them during a cloudy day---just before a rain if possible. If I can't wait for that, I water them a couple of hours before I move them--it seems to help the soil stay on the root ball better.

I am a big fan of nursery beds--it makes tending young plants easier (they are all together, can be mulched, watered, fed, protected from critters), and it is easy to compare the characteristics and growth rate of the seedlings.


    Bookmark   December 21, 2008 at 12:28AM
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if i put the seeds on a paper towel in fridg. do i cover the seeds with the paper towel or just lay them on top in side bag. i am very new to this. thanks mary

    Bookmark   February 1, 2009 at 8:28AM
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I have about 50 JRM and 20 Green that had been in peat, and when they started to sprout, the person that had them didn't know what to do with I took them. I don't know what she did, but it's apparent the poor things think it's spring! I want to "pretend" it's spring until they get a root system of some sort, then they can go dormant until spring.

I put them in a 72ct cell liner. They have all popped their little heads up out of the soil, but between now and when they put on their their first "real leaves" is a mystery. Usually when I get things to grow from seed like this, they get spindly and wind up falling over and dying. I have a mister bottle that I mist them with....I don't want to drown the poor things or cause them to rot off at ground level. I am trying to avoid this since I love JRM!

Once they are above to do I care for them until they get their first leaves? Thanks.

    Bookmark   November 6, 2013 at 2:14PM
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I have seeds that pop up everywhere from my 55 yr old tree. I let them grow where they start and if they survive after a year or so I put them in pots. Works well for me. I have 3 in pots and have given away to many to count.

    Bookmark   February 22, 2014 at 6:16PM
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Don't be afraid to try planting JM seed. Take seed from tree in Oct/Nov depending on Zone (I am 7/8) place in a cool dry place until Jan. Then place in crisper in fridge for 100 days. Take out and sew/broadcast in fertile soil with morning sun. The following Spring you will have more than you can process.
The picture is less than half of the seedlings from one tree.

    Bookmark   May 10, 2014 at 10:25PM
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