如何繁殖日本枫树

Frequently Asked Questions about Japanese Maples

This FAQ is just to amplify some points made in our introduction to Japanese maples. Go there for more information.

I want a real 'Crimson Prince', not a grafted one. Why can I only find grafted ones?

I have a 'Jiro shidare' that produces a healthy crop of seeds every year. Can I plant them to get more Jiro shidares?

You may have noticed that your children are not exact duplicates of you, even though they have a family resemblance. The only way to get an exact duplicate of you would be to clone you, which we're told isn't possible just yet. That's because humans reproduce sexually, so a child's genetic makeup is a mixture of both parents' and their ancestors' genes. Maples also reproduce sexually, so their children (seedlings) aren't exact duplicates of either parent. So far, so good.

But what if both parents are Crimson Princes? First, that's unlikely; pollen can be borne on the wind from who-knows-where, so it would take heroic measures to make sure both parents were indeed the same variety. Also, the genes expressed are not just those expressed by the parents; there is the whole ancestry to consider. A red-headed child can be born to two non-redhead parents if there are red-haired genes in the family. Same wiith trees.

Most cultivars are genetic abberations. The great majority of seedling Japanese maples in the wild have green, relatively broad leaves. So the great preponderance of genes in the pool will produce trees that look like that. The seedling of a 'Crimson Prince' is very likely to be green, not crimson. Even if it does look much like the parent as a seedling, you don't know how big it will get, how well the color will hold up in summer heat, whether it will have a dense or airy texture, an upright or cascading habit, etc., because there will be seedling variation. Just as you can't predict what your kids will be like when they're grown, seedlings are full of surprises.

Although humans can't yet be cloned (except for identical twins) plants can, and have been for at least hundreds of years. There are three basic ways of doing it with woody plants. One is to take cuttings, causing roots to form on a twig cut from an adult plant. The second is to graft that twig onto another tree and cut off all that tree's growth except for the transplanted twig. The third is to use micropropagation, sometimes called 'tissue culture', which involves using chemicals and special conditions to cause cells of an adult tree to become whole little trees. (Some non-woody plants can also be cloned by division.)

These three methods are referred to as vegetative, as opposed to sexual, ways of propagation. An important feature of vegetative reproduction is that the "child" only has one "parent", and so is genetically identical to that parent. Since it's genetically identical, it will also look like the parent if raised in similar conditions. You can see from this that the only 'real' Crimson Prince is one that's been propagated vegetatively. Grafting is the preferred method. (There's one excepton. The very first 'Crimson Prince' was a seedling. It's the only one more 'real' than a grafted one, but it's probably long dead or otherwise unavailable.)

Taking cuttings seems easier than grafting. Why not use that method?

Maples tend not to have vigorous roots. In a population of seedlings, some will have better roots than others. When we select seedlings to graft things onto, we try to select those with the most vigorous roots, and also to use seeds from vigorous-rooted trees to produce the next crop. But when we select new varieties, we're usually selecting for its leaves, not for the roots. And since the interesting varieties are genetic anomalies which might not even survive without human interference, the chances of their having vigorous roots is low.

It's possible to get Japanese maple cuttings to root. For a hobbyist, here's no reason not to try it. But the odds of the cutting growing into a vigorous tree, or even surviving, aren't nearly as good as if that same cutting were grafted onto a seedling that's known to have good roots. That's why commerecial nurseries are willing to pay skilled tradespeople who can graft hundreds of trees a day. If they could get by with paying unskilled labor to make cuttings, believe me, they would. In fact, some have. The nameless red maples found at big-box stores might be from cuttings, or they might be red seedlings. They might be ok, and they might not. There's no way to know in advance.

My 'Burgundy Lace' got broken off at the graft, but it's starting to sprout new leaves. Is it still alive?

The understock is, but the 'Burgundy Lace' isn't. Everything below the graft is a species Acer palmatum, and it's probably green. What's left will probably become an attractive tree, but it won't be the variety you purchased--or any variety. It will probably be bigger and a have differently-shaped and colored leaves. Scroll up and read from the top of this page if you want a more complete explanation.

On any grafted tree, the understock will proably want to grow too, at least for awhile. You should remove any of that growth below the graft; otherwise you will have two different kinds of trees growing, and the understock will probably be more vigorous than the scion (grafted portion), eventually taking over, or at least preventing the graft from growing as vigorously as it should. Removing the unwanted growth below the graft is easy; just rub it of with your thumb. If it gets too big for that, cut it off. You won't harm the tree.

How do you graft?

It's all in the wrist. Probably the best way to learn is to look for workshops sponsored by local nurseries. Failing that, here are some online guides:

We use a side veneer graft in July-September, and staple a plastic bag around the graft for a few weeks. A cut made on the rootstock is matched by an angle cut on the scion, and the two pieces are manipulated so that the cambium layers just beneath the bark are in as much contact as possibe. The arrangement is held together by grafting tape or rubber strips. The side veeneer graft is illustrated at the following link. The text applies to late winter/spring grafting, so ignore it if you're doing late summer grafting, which we recommend. Look at the description of the splice graft as well, to better see the angle of the cut.

http://www.ces.ncsu.edu/depts/hort/hil/grafting.html

Here's an article on grafting Japanese maples:

http://www.ag.auburn.edu/landscape/STGOnovember98.html#grafting

And here's a photographic walkthrough:

http://webpages.charter.net/wbshell/garden/graft1.htm

I want to start seeds so I will have seedlings to graft onto, or look for new cultivars to introduce, or just to plant them all over the yard. How's it done?

The easiest way is to let seedlings appear naturally from under your trees, but it doesn't always happen, and you'll get more if you start them yourself.

First, leave the seeds on the trees until September - November, depending on your climate. The wings of the seeds should be getting brown, but not the seed itself. Store them in a paper bag in a cool, dry place until you're ready to stratify them.

Stratification is just exposing the seeds to moist cold for 3 months or so. If you don't have a greenhouse or other protected area, you might want to find out your average last frost date (it's April 15 here) and start stratification 90 days before that.

Stratify by mixing the seeds 50-50 with moist peat moss, placing them in a plastic freezer bag, and putting them in the refrigerator for 90 days or until they start to sprout. Start checking a couple of weeks early, or more. Some use sand, vermiculite, or other material, but peat moss has a natural fungicide in it.

When they start to sprout, plant the seeds in a flat of potting soil. Put screen over the flat, or critters will find them. Water just enough to keep the soil barely moist. The flat can be outside in a shaded area, or in a greenhose under a bench, but they'll want a little sun once they've developed leaves.

It's very likely that not all the seeds will sprout, but, after pricking out and transplanting the seedlings (when they have 3 sets of true leaves), leave the flat, screened, outside the next winter, and the next. Some seeds will take that long to sprout.

As the seedlings develop, observe them to see if any have unusual characteristics, like, say, blue and yellow stripes. That's your money-maker. Select the most vigorous of the rest for understock or planting out.

I live in zone 5, where it sometimes gets 20 below. Can I grow Japanese maples?

Ayuh, you can grow some of them. You need to give the root area a heavy mulch before the ground freezes, the trees will probably not grow as tall or as fast as they would in warmer climates, and you may experience some dieback in the winter.

Many of the newer and more unusual cultivars simply have not been grown in very cold climates in sufficient numbers to know whether they are generally hardy there or not. If we know for sure a cultivar is not hardy in the coldest areas, we say so. If we don't mention it and they're not on the list below, we simply don't know. We'll know when enough people take a chance on them, or when universities or nurseries do field trials. Ya, sure.

Acer japonicum and Acer shirasawanum are generally a little bit hardier than Acer palmatum, and considered reliable in zone 5. These species include some of the most beautiful cultivars, as well as some with the most striking fall color. Although the species are taller than A. palmatum on average, most of the cultivars we offer are of similar size. The other species we offer, Acer circinatum is only reliably hardy to zone 6.

The following A. palmatum cultivars are considered hardy in USDA zone 5, assuming a mulch and protection from cold winds. Your mileage may vary. We don't offer all of these every year. Some other nurseries might offer other cultivars they consider hardy in zone 5.

Autumn Fire, Beni kagami, Beni shien, Beni ubi gohan, Bloodgood, Boskoop Glory, Brocade, Burgundy Lace, Butterfly, Chitoseyama, Crimson Queen, Emperor, Enkan, Fairy Lights, Fireglow, Garnet, Green Star, Heptalobum, Hogyoku, Ichigyoji, Iijima sunago, Inaba shidare, Inazuma, Kasigiyama, Kinran, , Korean Gem, Kujaku nishiki, Kurabu yama, Lion Heart, Lozita, Maiku jaku, Matsu kaze, Mikawa yatsubusa, Mizu kuguri, Moonfire, Nuresagi, O kagami, Omato, Orangeola, Ornatum, Osakazuki, Oshio beni, Pixie, Red Dragon, Red Pygmy, Rubrum, Rugose, Samidare, Seiryu, Sherwood Flame, Shishigashira, Skeeter's Broom, Sumi nagashi, Tamukeyama, Trompenburg, Utsu semi, Willow Leaf, Winter Flame, Yasemin, Yezo nishiki, Yubae, Yugure.

I live in a hot, humid, alligator-infested swamp. Can I grow me some Japanese maples?

You can grow some of them, but be careful when you go out to water. They will mostly want shade from the hottest sun. An exception is 'Beni shi en', a red variegate that was developed in Alabama, and reportedly does well in full sun. The same goes for the cultivar called 'E.P. The man who introduced it says that 'Fireglow' does well, too. Among dissectums, 'Tamukeyama' is perhaps the best choice.

What we know about how well various culitivars perform is mostly hearsay, based on anecdotal evidence. There haven't been many scientific field trials. Cultivars that folks say do well in the southeast as far south as north Florida include Arakawa, Beni maiko, Beni otake, Beni shi en, Bloodgood, Butterfly, Crimson Queen, Emperor, E.P, Fernleaf (Aconitifolium), Fireglow, Garnet, Glowing Embers, Hefner's Red Select, Inaba Shidare, Jordan, Kamagata, Kashima, Kiyo Hime, Moonfire, Omureyama, Orangeola, Oregon Sunset, Osakazuki, Red Select, Skeeter's Broom, Red Dragon, Sango Kaku, Seiryu, Shishigashira, Shindeshojo, Summer Gold, Tamukeyama, Tana, Vitifolium, and Waterfall. Other cultivars may do well, but again there is little data to go on in many cases.

In this kind of environment, you really want to spray for bacterial/fungal infections. See Disease Prevention.

This FAQ is just to amplify some points made in our introduction to Japanese maples. Go to that link for more information.