Page 6 - Sonoma County 2016 Gardeners Resource GUide.indd

Growing Japanese Maples
by Mike Umehara, Momiji Nursery
Momiji Nursery visitors often ask, “Can I grow a Japanese maple cultivar
from a seed or cutting?” Gardeners grow many of their favorite plants using these methods, however there’s more to the story when it comes to Japanese maple cultivars. Let’s go over some basics to reveal how we produce the many cultivars of the Japanese maple.
Plant propagation is a method of producing offspring that are genetically identical (clones) to the parent. There are two basic methods of propagation:
• Sexual propagation is when a plant is grown from seed.
• Asexual or vegetative propagation is when a plant is grown from a cutting or graft.
Seed, or sexual propagation is probably the easiest way to grow maples, but because maple cultivars have such genetically diverse variants, they don’t come true to the parent 100% of the time. Even when
a match seems to have been made, the growth habit of the maple must be observed for several years. This is a long, time consuming process.
On the other hand,
some people enjoy
growing from seed
precisely because of
the diverse gene pool of the Japanese maple—there is a chance of finding one unusual, fancy, unique maple in a batch of thousands of seedlings. This is one way nurseries select a new cultivar.
Grafted cultivars in the protection of a greenhouse
Asexual or vegetative propagation can be performed by sticking a cutting, or stem, into the growing media to develop a root system. This allows you to produce or clone a large amount of maples in a small space, but unfortunately the root system is not always strong. Some cultivars do not root readily and others not at all.
Grafting has been the most common method of cloning the maple cultivar. In the art of grafting, the closest analogy to a good grafter is that of the gardener with a “green thumb.”
The technique of grafting is very simple. The grafter joins the upper part, or scion, of a plant to the root system (root stalk) of another plant. The process requires matching the root stock’s growing membrane (cambium layer) with the desired plant’s scion growing membrane.
Because of the diverse genes of Japanese maples, it is important when selecting a scion wood that it is true to the desired cultivar. This is especially the case for variegated cultivars. For this reason, we like to graft the variegated cultivar during the summer grafting season so that we can see the good variegated gene.
The root stalk, or understalk, is a seedling of a green leaf, upright growing Japanese maple. The green leaf maple has an abundance of seeds that are produced annually. They are chosen because they are fast growing and have a hardy root stock. We pick the seedlings in fall and germinate them in spring, then grow them out for 2 or 3 years for use as understock.
When grafting, once the two membranes are fused or united together with callus, you can consider the process complete. If the graft has taken, be happy, but be vigilant and remove any new growth from the understock.
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The diversity of Japanese maples makes this species unique and special, but that can be the subject of another article.
Unfortunately, Japanese maples are not the easiest plant to graft. Some of the dwarf varieties have a stem so small that it almost takes magnifying glasses to match the two cambium layers. There are many different methods of grafting. We use the side veneer technique method here at the nursery and graft twice a year, winter and summer.