Bonsai trees grow very slowly from seed. Depending on the species, you may have to wait months for the seed to germinate. Some slow-growing or finicky species may even require several seasons to break through their seed coats. But if you’re willing to invest the time, you will be greatly rewarded. A bonsai grown from seed and well-cared for over the years can be uniquely shaped and passed down from generation to generation.
The Type of Seed
The species of bonsai that you choose to grow is entirely up to you. Having said that, there are a few basic guidelines you should follow when choosing bonsai seed.
For the best results, purchase your bonsai seed from a reputable nursery or tree dealer. Many species of tree make beautiful bonsai. The most commonly cultivated bonsai trees are fir, maple, pine, birch and cedar. Most of the species in these genera are relatively easy to grow and cultivate.
Maple, black pine, scots pine, beech and larch are the easiest to grow from seed and are great species for beginners to tackle. If you are a novice horticulturist, stay away from species like white pine, needle juniper or hornbeam which are notoriously difficult to germinate.
Once you settle on a species that is right for you, shop around for suitable vendors. Arborists with brick and mortar stores with friendly, knowledgeable clerks are an ideal choice. While you shop, you can get your questions answered by experts.
If no brick and mortar shops are available in your area, go online. There are many seed dealers available and you may be able to get a good price for quality seed. But remember to do your homework before you buy. Stick with sources that come with recommendations from online Bonsai forums or other experts in the field.
Whether you buy from a brick and mortar or online store, be sure to only purchase certified disease free seed. This seed has been bred and treated to resist the diseases most common to the species. This is especially beneficial when growing bonsai from seed. Untreated or wild seed often succumbs to damping off and other diseases before the seedlings reach their first year.
When buying, also keep in mind that there is no such thing as bonsai seed. Disreputable or misinformed vendors will sell seed labeled as “bonsai” at a markup. Avoid this seed. Any vendor who does not know enough about seed to know that there is no bonsai seed or is willing to defraud his customers for a markup is not one you want to patron.
Not all seeds are ready to sprout once they are put into soil. Several species of seed must be carefully prepared or stored before they are ready to sprout. Before you plant or even purchase your seed, do a bit of reading to familiarize yourself with its particular needs.
For example, certain temperate species of tree like maples must undergo cold stratification before they are ready to germinate. Cold stratification simply means a cold and moist period, usually the winter months. In nature, these seeds fall off of the mother plant in fall. They spend the freezing winter months on the ground. The cold period followed by warmer weather in spring triggers them to germinate. To germinate bonsai seeds that require cold stratification, place the seed in a plastic bag filled with potting soil (link to soil page) that is kept consistently moist. Place the bag in the refrigerator’s vegetable crisper for the number of months that seed species must germinate. Then, pot it out in spring.
Other species like eucalyptus must be scarified. Their seeds are designed to germinate only under certain conditions. Most of these species have hard shells that must first travel through the digestive tract of an animal or be subjected to fire before they can germinate. When growing a bonsai tree from seed at home you can bypass these extreme measures with simple scarification. Simply file gently through the hard seed coat just until you reveal the lighter coat underneath. The seedling will break through the opening and germinate in spring.
Most tree species like pine and maple do well in well-draining, organic commercial potting soil (link to soil page). Never use garden soil for your bonsai tree’s pot. It is too heavy for a pot and unsterilized. Your seed may not survive it.
Fill a pot (link to pots page) with drainage holes to within 1/2-inch of its lip. Place coffee filters over the drainage holes if soil crumbles out of them. Water the soil (link to watering page) liberally and allow it to drain for 30 minutes.
The depth at which you plant your bonsai tree seed depends heavily on the species of the tree and the size of its seed. As a general rule, most seed should be planted at a depth equal to the diameter of the seed. Very small seed should just be lightly covered with a thin layer of soil. Acorns may be planted as deep as 2-inches.
Keep your bonsai seed moist with regular watering until it germinates. Touch the surface of the soil daily to check moisture levels. Water the soil as necessary with a fine spray of water from a spray bottle. Keep the soil from drying out quickly by placing the container in indirect sunlight, never direct. Indoors, near a large window is an ideal spot for maintaining the moisture and light levels your bonsai seed needs to germinate.
The amount of time your bonsai seedling takes to emerge from its seed depends on the species. Some will germinate in as little as a few weeks. Others will take several seasons. Once your bonsai seedling successfully breaks from its seed and develops two true leaves – the leaves that sprout after the first two immature leaves -cut back watering to whenever the top third of the soil in the container dries out.
Once your bonsai tree outgrows its seedling tray, pot it up to a larger pot (link to pots page). Insert a pencil beneath the seedling’s roots and push up to remove it from the soil. Never pull it by its delicate stem.
Once your bonsai tree seedling is planted in a larger container, you may care for it as you would any other bonsai tree. Move it to direct sunlight and water it regularly. Once the tree is five to six weeks of age you may begin a fertilization regimen.