Germinate Japanese Maple Seeds
Japanese maple seeds are not that difficult to germinate. I have germinated thousands of Japanese maples from seed. This is one of my specialties. I use them for grafting purposes. I am the owner of Japanesemaplesandevergreens.com and I have been in the nursery industry for 15 years.
Japanese Maples produce their seeds in the fall. This is the optimum time to collect them. Try to collect the seed before they are completely mature. When the seeds have turned reddish-green they will be ready to harvest. It is important to collect the seed before they dry out. If the seed is collected after they have dried they will have a hard seed coat. The hard seed coat makes it difficult for water to get through the hardened seed coat where the embryo lives. The embryo needs water in order to grow. An embryo is the life source of the seed. It contains all of the genetic data that will tell the Japanese maple how to germinate and grow into a tree. It really is quite fascinating. If your seeds get seed that has already dried then this may delay germination for two years. If you have seeds with hardened seed coats soak the seed in warm water (110° F) for two days followed by a cold moist chilling period in peat moss for 120 days. You may plant them directly outside in a raised seed bed or a cold frame. You may plant the seed in moist peat moss or in a germination mix. You can buy peat moss or a germination mix at any garden center or home supply warehouse. When I go to plant my Japanese maple seeds I generally use the scatter technique. You may choose to direct sow them into single containers but germination is variable and you will have empty pots. Next I cover the seeds with about ¼ inch of germination mix or peat moss. I recommend mixing in a starter fertilizer. You can find starter fertilizer at your local garden center.
Remember germination is variable and you never know what you are going to get. So collect a lot of seed to be sure you get plenty of Japanese maples. You can always toss out any maples that are weak or are not suitable for your purposes. Be sure to leave the seedling undisturbed for a full season before you transplant them into the field or larger containers.
If you would like more information on how to germinate Japanese maple seeds check out my in-depth eBook on kindle. How to Grow Japanese Maple Seeds: Tips and Techniques From a Nurseryman