Plants come in all shapes and sizes, and even the mighty oak tree can be convinced to grow no larger than a house cat. Our expert Robert Sablowski reveals whether there’s a towering giant waiting to burst out of your bonsai.
It’s a question many of us may have asked while marvelling at a well-pruned bonsai. If this is a miniature version of a large tree, would planting it in the ground unleash its true potential? The answer is yes, probably. “Plant development is famous for being very flexible, and very dependent on the environment,” says Sablowski(opens in new window), head of the Cell and Developmental Biology Department at the John Innes Centre. “The reason why a bonsai tree is small is because it is under constant pressure, and constant constraint,” he adds. The physical expression of most living organisms – the phenotype – results from a combination of genetic instructions and the surrounding environment. Humans grow from a genetic plan executed while we’re in the embryo, with comparatively little development after birth. Plants, on the other hand, continuously form new organs including leaves, roots and flowers, which originate throughout the plant’s lifetime from structures known as meristems. This constant regrowth from source is what makes them so flexible. “Every moment is a new opportunity to respond to a change in the environment,” Sablowski explains. Meristem cells in bonsai trees are the same as in their larger counterparts, with similar genetic instructions. “Given access to enough nutrients, light and water, they’ll try to do what they’re genetically programmed to do, which is to produce a normal tree.” Through the EU-funded SOS-CROPS project, Sablowski investigated some of the genetic underpinnings that control plant growth. Shorter crop plants produce greater yields in agriculture, as taller versions are more vulnerable to the elements like wind and rain. Agronomists have therefore bred smaller versions, but this can result in unwanted side effects. Sablowski’s team tried to over-activate a gene controlling stem growth as an alternative way to produce a shorter plant. The work shed light on how plants control their size. If you’re thinking of turning your bonsai big, Sablowski cautions that while the plant should reach its full potential, there could be one small architectural hiccup: “You may see the remnants of a tiny bonsai trunk at the bottom of the tree.” Best to plant it out of the wind. Click here to find out more about Robert Sablowski’s research: Are plant height and shape genetic?
Bonsai is the ancient Japanese art of cultivating miniature trees in containers The practice involves carefully pruning and shaping trees to create elegant living art But did you know you can also grow bonsai trees directly in the ground?
Planting bonsai trees in the ground can offer some advantages for training and developing these miniaturized trees. With the right techniques gardeners can use the ground to enhance their bonsai cultivation skills.
In this complete guide, we’ll cover everything you need to know about successfully growing bonsai trees in the ground, including:
- Benefits of ground growing bonsai
- Best trees for in-ground bonsai
- When to plant bonsai in the ground
- How to plant bonsai trees in the ground
- Caring for ground-planted bonsai
- Bringing trees back into pots
- Challenges to watch out for
Why Grow Bonsai in the Ground?
Growing bonsai trees in pots limits root development. Planting in the ground allows roots to spread freely and access more nutrients and moisture. This can offer several advantages:
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Faster trunk thickening: The trunk base flares out as roots expand unrestricted.
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Stronger trees: Robust roots and trunks make trees more resilient.
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Bigger foliage: More access to light and nutrients results in larger leaves/needles.
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Lower costs: Avoid expenses for specialized pots, soil, and frequent watering.
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Cold protection: The ground insulates roots better than containers in winter.
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Pre-bonsai development: Fast unchecked growth creates suitable pre-bonsai stock.
The ground provides ideal conditions for rapidly developing bonsai trunks, branches, and roots. Just be sure to monitor and prune regularly to maintain the desired miniature size.
Best Species for In-Ground Bonsai
While nearly any bonsai tree can be ground-grown, some good choices include:
- Maples
- Pines
- Junipers
- Elms
- Oaks
- Fruit trees like crabapple
- Flowering trees like cherry blossom
Conifers, especially pines and junipers, respond particularly well to ground planting. Their roots can spread more extensively when unconfined by pots.
Avoid finicky trees that require precise environmental conditions, as the ground exposes them to less controlled growing parameters.
When to Plant Bonsai in the Ground
The best times for putting bonsai trees in the ground are:
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Early spring: Roots have the whole growing season to establish before winter dormancy.
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After root pruning: The ground helps regenerate damaged feeder roots.
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While training trunks: Thickening occurs much faster in the ground.
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Winter dormancy: The earth protects roots better than pots in cold climates.
You can also plant nursery stock or pre-bonsai in the ground for several years to cultivate raw material for future bonsai projects.
How to Plant Bonsai Trees in the Ground
Follow these steps for properly planting bonsai trees in the ground:
Choose a Site
Select a sheltered spot that gets full or partial sun. Well-draining soil enriched with organic matter is ideal. Amend dense clay or sandy soils if needed to improve drainage and fertility.
Prepare the Tree
Carefully remove the tree from its pot without damaging roots. Comb out any encircling roots that could choke the tree. Prune back any excessively long or thick roots.
Dig a Planting Hole
Make the hole slightly wider than the root spread and no deeper than the original soil level in the pot. The top root should sit just below the surface.
Backfill the Hole
Fill in around the roots with a blend of the native soil and a coarse amendment like grit, sand, or bark chips to improve drainage. Pack the soil firmly as you backfill to stabilize the tree.
Water Thoroughly
Water deeply after planting to saturate the backfill soil and eliminate any air pockets. Allow excess water to drain away.
Apply Mulch
Spread 2-3 inches of organic mulch like bark or wood chips around the base to conserve moisture and suppress weeds.
Stake If Needed
Stake tall, top heavy trees with bamboo poles or wood stakes to protect from strong winds and animals. Avoid using wire or tags that can cut into the bark.
Caring for Bonsai Trees in the Ground
In-ground bonsai trees require similar care to their potted counterparts:
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Watering: Check soil moisture frequently and water whenever the top few inches become dry. Target the roots, not the foliage.
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Fertilizing: Apply a balanced organic fertilizer or slow-release pellets in early spring. Boost nutrition monthly during the growing season.
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Pruning: Trim back new growth often to maintain the desired miniature size and refined form. Prune judiciously in spring and fall.
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Pest/disease control: Monitor for common issues like insects, mites, fungus, and mildew. Treat any problems promptly.
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Weeding: Keep grass and weeds cleared from the base of the tree. They compete for water and nutrients.
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Mulching: Replenish mulch as needed to retain soil moisture and suppress weeds.
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Protection: Guard against lawn mowers, string trimmers, and animals that could damage the tree.
With attentive care, in-ground bonsai trees will thrive and develop nicely for future potting and training.
When to Bring In-Ground Bonsai Back Into Pots
Bonsai trees typically remain in the ground for:
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1-6 years for considerable trunk thickening
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1 full growing season for root regeneration after root pruning
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6 months up to 1-2 years for recovery after major work
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3-10 years to cultivate pre-bonsai stock
Monitor growth and root spread. As the tree approaches the desired trunk girth and form, it’s time to dig it up and pot it for further bonsai training. Carefully inspect the roots and prune aggressively to accommodate the bonsai pot.
Challenges of Growing Bonsai in the Ground
While ground growing provides benefits, it also comes with some potential drawbacks to consider:
- Overgrowth if left unpruned
- Surface roots that disrupt root flare
- More exposure to pests and diseases
- Reduced control over watering and feeding
- Environmental stresses like frost, wind, and extreme heat
- Difficulty transitioning from open ground to confined pots
Success requires vigilant care and intentional timing of the shift from ground to container.
The Takeaway
Growing bonsai trees in the ground can be a valuable technique for rapidly developing thickness and movement in trunks and branches. It allows the roots ample space to spread unrestricted.
Select young, vigorous trees that are resilient to your climate. Allow them to grow freely with minimal pruning, then pot up for refinement as they approach the target size. Maintain care while in the ground and monitor growth regularly.
With patience and proper process, planting bonsai trees in the ground can help create impressive specimens with aged, substantial trunks. Just be sure to transition them back into pots before they outgrow their intended scale.
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Why Growing Bonsai in the Ground is a Game Changer
FAQ
What is a bonsai tree in the ground called?
Although in some cases dwarf trees are used for bonsai, if a bonsai is planted in the ground it will eventually grow into a full-size tree or plant. There are landscape style bonsai; they are generally called Penjing (which is also the Chinese term for bonsai).
Can I plant a bonsai tree in regular soil?
What is the rule of 3 in bonsai?
The “Bonsai Rule of Three” is a design guideline that emphasizes the use of three main elements – trunk, branches, and foliage – to create a harmonious and visually appealing miniature tree.
Can a bonsai tree survive outside?
Yes, bonsai trees can be kept outside. In fact, most bonsai trees thrive when kept outdoors, exposed to natural elements and seasonal changes.