By Michael J. McGroarty
Perry, Ohio Copyright 2011
Growing Japanese Maple trees from seed is a lot easier than most people think. However, it is important to understand that there are more than 250 different cultivars of the Japanese Maple tree, and my purpose through this website is to introduce you to as many of these different cultivars as I can. Or more appropriately, as we can, because the purpose of this web site is to develop a community of Japanese Maple Lovers and collectors.
Japanese Maples come in all kinds of different sizes, different shapes, and have a variety of different growing characteristics. They also have as many different variations of leaf size and shape as you can imagine. And that’s why the Japanese Maple is by far, one of the most versatile plants you can add to your landscape. The different varieties are so unique that you can easily use several of them in a residential or commercial landscape without the slightest hint of redundancy.
However, all of this tends to complicate the process of propagating Japanese Maples because very few of these numerous cultivars will come true to the parent plant when grown from seed. So . . . you might ask, how do I go about propagating a Japanese Maple?
There are a number of methods which include growing them from seed, grafting a piece of the desired variety onto a Japanese Maple seedling, and budding. Budding is really just another form of grafting, except instead of using a small cutting from the desired parent plant, you work with a single bud from the desired plant. Some Japanese Maples are also grown via tissue culture which involves a laboratory and test tube like conditions.
You and I at home? Let’s stick to the basics of growing from seed, grafting and budding. In order to graft or bud, you must first have a Japanese Maple seedling that you can use as the rootstock. So for the remainder of this article we’ll discuss growing from seed.
The majority of the Japanese Maples you’ll encounter in your daily travels are from the Acer palmatum family, so that’s what we’ll discuss in this article. First allow me to explain exactly what Acer palmatum means in terms that you and I can understand. All plants have a common name and a Latin name. The Latin name is really the most dependable way to identify a plant because many plants end up with numerous common names, depending upon who you are talking to. But there should always be just one Latin name.
So let’s break down the Latin name Acer palmatum. Acer is the generic name, or the genus, and Acer is used to identify any maple tree. Palmatum is the species name and in this case means that the maple tree being identified is from the Japanese Maple family. Acer palmatum means Japanese Maple. Next we add the variety to the Latin name. As in; Acer palmatum dissectum. Any Japanese Maple that has a variety of dissectum in it’s name is a mounded, low growing tree with leaves that look like they’ve been dissected. Commonly called ‘cut leaf’ or ‘lace leaf’. Acer palmatum dissectum. To the end of that we’ll add the cultivar name, as in Acer palmatum dissectum ‘Crimson Queen’.
There are a lot of Acers, a lot of Acer palmatums, and a lot of Acer palmatum dissectums. But there is only one Acer palmatum dissectum ‘Crimson Queen’. That describes a very specific kind of Japanese Maple and that particular variety, as with all specific varieties, can only be reproduced through a means of asexual reproduction.
Sexual reproduction is what happens naturally. A seed falls to the ground, germinates and a Japanese Maple seedling emerges. Of course it’s not quite that simple, and I’ll explain how to make the process more predictable. Asexual reproduction is any form of propagation that is not natural. Rooting cuttings, budding, grafting or reproducing plants via tissue culture are all forms of asexual reproduction.
So . . . with all of that explained, let’s discuss growing Japanese Maples from seed and hopefully through my long winded explanation you now understand that when growing just about any plant from seed, the results are not always predictable. Much like human reproduction via sexual means, we all look similar, yet each and every one of us is different.
With plants there are advantages and disadvantages to those mixed results. When growing from seed you never really know for sure what you are going to get. But in the case of Japanese Maples, you at least know that if you sow seeds of Acer palmatum you’ll get Acer palmatum seedlings. They may not have that beautiful deep red color, but it’s almost certain that your seedlings, even if the leaves are as green as grass, they’ll make good quality root stock trees for grafting or budding. They will be compatible with any cultivar of Acer palmatum that you’d like to graft or bud onto them.
We also know that if you collect your Japanese Maple seeds from a tree with deep red leaves, there’s a really strong chance that many of your seedlings will have leaves that are deep red in color. They won’t all have deep red color, some of them will be green and some will show different shades of red. If you collect your seeds from a Japanese Maple that has green leaves, chances are most, if not all of your seedlings will have green leaves.
Now this is important because a lot of people get confused with this. ‘Bloodgood’ is a named Japanese Maple cultivar. It is so named because it has deep red leaves that hold their color all summer long. At some point in time all ‘Bloodgood’ Japanese Maples will put out a crop of seeds. You can collect those seeds and grow them with the instructions I will give you below. But no matter what, no matter how red the leaves on your seedlings are, they are not, and cannot be called ‘Bloodgood’ because they will have been produced via sexual reproduction and are not identical clones of the parent plant.
Some growers and or vendors twist this a little by calling them ‘Bloodgood’ seedlings, but I don’t like and don’t agree with this practice at all. They are not ‘Bloodgood’ and that name should not be used when describing them. What they really are is Acer palmatum ‘Atropurpureum’ which is a Japanese Maple seedling with red leaves. So, when growing Japanese Maples from seed you’ll get one of two different plants. Acer palmatum, or Acer palmatum ‘Atropurpurpeum’. The first will have green leaves, the second will have red leaves.
That’s a lot of words, but it is intended to give you a good foundational knowledge of Japanese Maple propagation. Now let’s get to the basics of growing them from seed.
Japanese Maple trees flower in the spring. Of course the flowers don’t look anything like a flower from a distance, but viewed closely they very much resemble a tiny but beautiful bloom. For the most part they are inconspicuous and usually go unnoticed. But as with all plants you first need a bloom, then some sort of fruit, then within the fruit you find the seeds. On any kind of maple tree, the seeds are trapped in a winged seed pod that most of us as kids called “helicopters” because the pods spin like the blades of a helicopter as they fall from the tree.
After the tree flowers in the spring the seed pods begin to form. You must leave them on the tree all summer, into the fall to allow them to mature. If you collect the seeds too soon the embryo inside of the seeds will not be completely mature and the seeds will not be viable. The rule of thumb is to leave the seed pods on the trees until they start to turn brown and can be removed from the tree fairly easily with little resistance. Here in northern Ohio, zone 5 this usually happens around mid to late October. If you wait too long you’ll lose out because once the seeds start falling it happens quickly. If you find a bunch of seeds on the ground by all means pick them up, they are still perfectly fine and viable.
Once you’ve collected your seeds the goal is to sow them and get them to germinate. But this is a little tricky. Not at all difficult, but you do have to trick the seeds with a process that is called stratification. Japanese Maple seeds have a really hard outer coating that protects the embryo. In order for the seeds to germinate you have to take some steps to soften that outer coating, so water and oxygen can find it’s way inside of the seed.
In nature the natural process is not very efficient and it can often take up to two years, maybe longer, before the seeds actually germinate. That poses a problem because the timing might be way off, and the little tiny seedling might start emerging right before winter and have no chance at all of survival. By following one of the three different methods that I am going give you here, you will actually control when the seed germinates, thus giving you a much higher percentage of success.
Method #1 is to sow the seeds immediately after you collect them. This is a pretty simple process and it can work really well. Of course with this method you are at the mercy of Mother Nature, but it’s still quite predictable. Not sure? Do some of your seeds both ways and see for yourself which one you like the best.
Where do you get Japanese Maple seeds? You can buy them if you want. There is a lot of debate about the quality of purchased Japanese Maple seeds, and the quality can and will vary from vendor to vendor. There are all kinds of vendors online that sell seeds. My goal here at Japanese Maple Lovers is to put together a list of seed suppliers you can buy from if can’t find any seed locally. What’s really important is to get fresh seed, and if you want your seedlings to have red leaves you have to know the details of the tree from which the seed is collected. That’s why finding your own local source is the best option.
With that said, once you set your mind on growing Japanese Maples from seed, you will start seeing all kinds of large Japanese Maples in your hometown. You might see these trees in local parks, cemeteries and in peoples yards. You must ask permission to collect seeds from any tree that you do not own, but usually most people are happy to allow you to collect seeds from their tree. However, since you’ll probably want to go back year after year, you should gift them with a few of your seedlings. Maybe even gift them with a small Japanese Maple that you’ve purchased, and by all means after you collect the seeds send them a thank you card and possibly a gift card for a local restaurant. If you do this, you are likely to have a perpetual supply of Japanese Maple seeds for a long time to come.
Method number one is good for colder zones like zones 4, 5, 6 and probably zone 7. Not sure what cold hardiness zone you’re in? Just do a Google search for “cold hardiness zone map”.
1. Immediately after you collect your seeds dump them out on a work table. One by one pick the seeds up and break the wing off. Discard the wing and keep the part that contains the seed. How do you know for sure which part is which? The wing looks very much like the wing of a large insect. It has veins and it’s quite brittle. The part that contains the seed obviously has a bulge and is not at all fragile. Don’t be overly concerned about whether or not you broke off enough wing. What’s really important is that you keep the part that contains the seed. If there’s still a little wing attached that’s not a problem.
2. Put the seeds in a container that will hold hot water. Run the water from your faucet until it’s quite warm, but not so hot that you can’t put your hand under it. But close to that hot. Pour the warm to hot water over the seeds and just let them soak in the water for 24 hours. At first the seeds will float, but eventually they’ll almost all sink to the bottom. The ones that never sink are probably not viable, but it won’t hurt to sow them with the rest. Maybe they just didn’t get wet enough to sink.
3. Once the seeds have soaked in the water for 24 hours pour off the water and spread the seeds out on a paper towel. You can allow them to dry overnight to make them easier to work with. Next fill a flat with a good seed starting mix that drains well. I suggest mixing some additional Perlite into the mix to make sure it will drain well.
If you don’t have a flat just go to the dollar store and buy a plastic dish pan, and drill many 1/2″ holes in the bottom so any water that drains to the bottom can escape from the dish pan. The holes you drill should be no farther apart than one inch.
4. Sow the seeds on top of the seed starting mix and press them down lightly so they are embedded in the growing medium. Then lightly sprinkle a covering of seed starting mix over top of the seeds. The light covering of mix should be no more than 1/4″ deep. 3/16″ deep would be ideal.
5. Next cut a piece of hardware cloth (heavy screen) so it fits tightly inside the dish pan. The purpose of the hardware cloth is to keep mice, chipmunks or other critters from digging in the dish pan and eating your seeds. The openings in the hardware cloth can be anywhere from 1/4″ to 1/2″. Consider using light wire, twist ties, or zip ties to fasten the hardware cloth to the top of the dish pan so the critters can’t pull it up to get to the seeds. The hardware cloth does not have to be suspended above the soil in the dish pan, because come spring you will remove the hardware cloth long before your seeds have a chance to germinate. So just lay the hardware cloth on the growing medium. The fasteners are only to keep the hardware cloth from being blown out or removed.
6. Now it’s time to set the dish pan and Japanese Maple seeds outside in the elements. Weren’t expecting that were you? It’s important to understand that Japanese Maple seeds require a lengthy treatment of cold before they will germinate. It’s part of the natural process. So what we are doing here in method #1 is trying to closely mimic the natural process, but we are better controlling some of the environmental conditions so the results are more predictable.
When deciding where to place your dish pan of seeds in your yard, select a place that is out of the wind and hopefully in a spot where dogs, skunks or raccoons won’t disturb it or tip it over. The goal is not to keep it from freezing. It can and will freeze, and that’s fine. It might stay frozen all winter. That’s not a problem. Snow cover is also fine. Snow is actually an excellent insulator and would be really good for your seeds. Freezing won’t hurt them, but it does slow down the stratification process. So, if they were naturally covered with snow for long periods of time during the winter chances are the growing medium would not freeze, or would not stay frozen. That would be perfect. Just set the flat or dish pan out in your selected location and forget about it.
7. As spring starts to arrive check on your container to make sure nothing is sprouting yet. As soon as the seeds start to sprout you need to remove the hardware cloth, but you don’t want to remove it too soon. In the early spring, just about the time the leaves start to come out, remove the hardware cloth from your growing container. At this time make sure the container is in a shaded location. About 40% to 50% filtered sunlight would be ideal. Water the growing medium as necessary, but don’t keep it soaking wet. It’s important the growing medium be allowed to dry and warm up before you water again. The seeds need some water, but should not be soaking wet. But more importantly the seeds need to be warm come spring so they start germinating. That’s why you should water only when needed so the growing medium stays warm.
8. You’ve done all you can. Now it’s up to Mother Nature. Be patient. Growing Japanese Maples from seed is a slow but highly rewarding process. In two to three weeks if the weather is warm, you should see seedlings start to pop up. The first set of leaves they produce are called cotyledons. The cotyledons will not look at all like Japanese Maple leaves. Cotyledons are actually part of the embryo from within the seeds and help to nourish the little seedling until the true leaves appear and take over. Once the true leaves appear the cotyledons wither and disappear. At that point photosynthesis begins and your little seedlings are well on their way to becoming beautiful little trees, each with their own unique characteristics.
9. At some point your Japanese Maple seedlings will have to be transplanted so they have more room to grow and develop. You can do that as soon as they germinate by simply picking them out of the flat with tweezers and re-planting them in a flat where they’ll have more room, or you can transplant them into a cell pack. Cell packs are the flimsy, lightweight trays that annual flowers are grown in. Cell packs are nice because you can later remove the seedlings from the cell pack in nice little root balls. Cell packs are tapered so plants can be easily removed without disturbing the roots.
Or you can just leave the seedlings in the flat you started with, then at the end of the growing season when they are dormant remove and separate them. Even if they are really close together that’s usually not a problem for the first growing season. Throughout the first growing season make sure your seedlings only get about 50% sunlight, since direct sun will burn their leaves. After the first season I plant mine out in direct sun here in zone 5. They’d probably benefit from at least some sun and if you are in a warmer zone you should consider some shade. The older they get the more sun tolerant they are, but Japanese Maples in general take a bit of beating in the direct sun. Usually the damage isn’t serious, just some browning around the edges. All of the Japanese Maples in my yard and even the ones in the nursery are in full sun. Only the young ones get a little protection with me.
Method # 2
1. In this method you will collect the seeds in fall just as they start to turn brown. Collect the seeds simply by pulling them from the tree. They should come off the tree easily. Place the seeds in a paper bag and store them in a cool dry place. A basement or garage is fine. You are not going to do anything with those seeds for a few months, they’ll be fine in the paper bag as long as they are dry.
2. Establish the “target date” that you can safely plant your seedlings outside. Here in northern Ohio, zone 5 we are usually safe from frost after May 15th, so that is my target date. So I will count backwards from May 15th, counting back 100 days. That takes me back to February 5th. On February 5th I will retrieve my seeds from the paper bag, break off the wing as describe above and soak them in warm to hot water for 24 hours as described in method #1.
3. After soaking in water for 24 hours you need to mix the seeds with a combination of sand and peat moss, or a seed starting mix that contains some extra perlite. You will also need a large zip-lock type freezer bag, but of course that depends on how many seeds you have. Fill the plastic bag about 1/2 to 3/4 full with the growing medium to make sure have the right amount. Dump the growing medium out of the bag into a bowl. Pour the seeds into the bowl on top of the growing medium and mix them together with your hands. Next sprinkle some water on the mix and mix it some more. You want the growing medium damp, but not soaking wet. After mixing the seeds and the growing medium thoroughly pour the combination back into the zip bag.
4. Press down on the bag to force most of the air out, then poke about three holes near the top of the bag for just a little ventilation. Place the bag in your refrigerator. Don’t put it way to the back of the refrigerator because it’s usually colder back there and the medium might freeze. Although freezing won’t hurt the seeds, it will slow down the stratification process.
The Japanese Maple seeds need a 90 day cold treatment to initiate the germination process. Ideally they should between 38 degrees F. and 50 degrees F. In other words, about the same temperature as the main area of your refrigerator where you keep your milk. From time to time check on your seeds and make sure you do not have a mold problem. Some people add a little fungicide to the mix from the beginning to prevent mold, but I don’t think it’s necessary. Should some mold develop just add some fungicide at that time. Brand doesn’t matter, just a general fungicide from the garden store. Use only a small amount of fungicide.
5. After 90 days in the refrigerator remove the bag and inspect it for germinating seeds. If you see little sprouts pick those seeds out of the bag and plant them in a flat of seed starting medium. Just poke a little hole in the soil, press the seed into the hole and leave the sprout sticking out. If there are no sprouting seeds, or few sprouting seeds just leave the bag out on the counter at room temperature and within a week you should see more and more seeds sprouting in the bag. Remove the sprouted seeds and leave the bag at room temperature until no more seeds seem to be sprouting.
Do not discard the mix in the bag because there are probably seeds in there that are going to take longer to sprout, so just pour the mix into a flat and place it outside where it’s warm. Keep the flat watered but not soaking wet.
6. The sprouted seedlings that you planted in the flat are going to need some sunlight as they grow so you’ll either have to give them some artificial light for a few weeks or move them outside into a shaded area. They need a little sunlight, but direct sun will burn them up. From there just care for them as you would any seedling.
Method # 3
1. This method is very much like method number two, but with this method you soak the seeds for 24 hours. Change the water, using more warm water, soak them for another 24 hours, change the water and soak them for another 24 hours. So that’s a total of 72 hours of soaking.
2. After soaking spread the seeds out on a brown paper towel, you know, the kind that you find it restrooms at public buildings. The brown towels are just about the right consistency, but any paper towel will work. I’d say the cheaper brands would be better for this purpose. Spread the seeds out in a row on the towel then fold the towel over top of the seeds a couple of times. Dampen the paper towel and place it in a plastic bag and place the bag in the refrigerator for 90 days as described above. After 90 days start checking on the seeds just as described above.
3. The seeds will sprout inside of the paper towel and you can pick them off the towel, or cut the towel around the seed. If some of the towel is stuck to the seed that’s fine, just plant the seed with a little towel stuck to it. Some people have told me they use toilet paper because it falls apart and the sprouted seeds are easier to harvest.
So, there you have three different methods. They all work. Pick one or try two, or all three. But by all means do at least one, don’t allow indecision to hold you back.
Have fun growing Japanese Maples from seed!
You never know what you are going to get, maybe the next really, really interesting variety.
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