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, 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?
Growing bonsai trees in the ground can be an effective technique for developing thick trunks and vigorous root systems. While keeping bonsai trees in containers is the norm, temporarily planting them in the earth provides certain benefits that can enhance their training.
In this comprehensive guide we will cover everything you need to know about cultivating bonsai trees in the ground.
Why Grow Bonsai in the Ground?
Growing bonsai trees in the soil offers several advantages over container cultivation alone
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Faster trunk and root growth – The ground provides more space for roots to expand and access more moisture and nutrients. This fuels increased vigor and girth development.
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Recovery from root binding – Time in the earth allows damaged feeder roots restricted by pots to regenerate.
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Healing after major work – The less stressful ground conditions promote recovery after heavy pruning, root work, collection, etc.
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Cold hardiness – The ground insulates the roots better than containers left outdoors in winter.
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Pre-bonsai training – Quick unchecked growth in the ground yields suitable stock for starting raw material.
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More taper and movement – The trunks flare outward at the base and can be shaped with less restriction.
The extra vigor and root expansion from ground growing is useful for rapidly developing various bonsai attributes. But it requires diligent monitoring and maintenance.
Best Species for Ground Growing
Nearly any tree can be planted in the ground for bonsai purposes. But some of the most responsive types include:
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Deciduous trees – Maples, elms, oaks, magnolias, cherries, crabapples.
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Conifers – Cedars, pines, spruces, firs.
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Flowering/fruiting trees – Azaleas, crepe myrtles, Beautyberry.
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Shrubs – Cotoneaster, pyracantha, junipers.
Trees with naturally expansive root systems often thrive when ground grown, as do collected specimens in need of rehabilitation. Carefully select suitable plants for your climate and conditions.
Key Benefits of Ground Growing Bonsai
The main advantages of cultivating bonsai trees in the ground include:
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Thickening trunks – The base progressively flares outward as the roots spread unimpeded.
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Powerful surface roots – Surface roots emerge as the tree seeks moisture and nutrients.
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Better taper – The girth tapers from the swollen base up to the apex.
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Vigorous growth – The branches and foliage become more lush and healthy.
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Budding back – Deciduous trees readily generate new shoots on old wood.
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Root regeneration – Damaged roots quickly rejuvenate when given space.
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Cold protection – The surrounding earth better insulates the roots from freezing temperatures.
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Pre-bonsai stock – Unrestricted growth generates material with potential for development.
When to Plant Bonsai in the Ground
Suitable times to transfer bonsai specimens into the ground include:
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Early spring – The roots have the full growing season ahead to establish.
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After collection – To help newly collected stock recover from significant root loss.
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After root pruning – Allowing the fine feeder roots to regrow more vigorously.
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When training trunks – The girth expands much quicker in the earth.
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Overwintering – The soil protects the roots better than being left potted.
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Long term pre-bonsai – For several years of unimpeded juvenile growth.
Avoid planting weakened trees in the middle of summer. Carefully monitor ground planted bonsai and remove for pot culture once goals are achieved.
How Long to Leave Bonsai in the Ground
The ideal duration for leaving bonsai trees in the ground depends on the purpose:
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Trunk development – They typically require 1 to 6 years in the ground for measurable thickening.
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Root rejuvenation – Damaged roots may only need one full growing season to regenerate once given space.
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Post-work recovery – Weakened trees may require 6 months up to 1-2 years in the ground to fully regain vigor.
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Pre-bonsai stock – Young plants often grow in the earth for 3 to 10 years based on their eventual target size.
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Overwintering – Bonsai are sometimes left in the ground just for a single winter before being potted up again.
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Seasonal rotation – Some enthusiasts plant their bonsai in the earth each summer and return them to pots in fall.
Evaluate growth periodically and remove trees for further bonsai training before they overgrow their intended scale or the roots escape control.
How to Plant Bonsai in the Ground
Follow proper technique when planting bonsai trees in the ground for the best results:
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Select a sheltered spot in full sun with well-draining native soil, amending if needed.
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Carefully remove the tree from its container without damaging the root ball. Comb out encircling roots.
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Excavate a hole slightly wider than the root spread and backfill with a blend of native soil and aggregates like grit or bark.
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Set the tree at its original growing depth. Water in thoroughly to settle the roots and top dress with mulch.
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Stake tall, top heavy trees as needed to protect from wind/animals while establishing.
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Monitor for surface roots emerging over time and cover them with additional soil.
Caring for Ground Grown Bonsai Trees
Properly caring for bonsai trees planted in the ground helps optimize their health and development:
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Watering – Provide supplemental water during dry periods so the soil never fully dries out.
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Fertilizing – Regularly apply organic fertilizer worked into the soil to nourish the increased vigor.
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Pruning – Maintain the bonsai form with pruning. Control leggy growth and strong sacrifices.
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Pest/disease control – Monitor closely and take preventive/curative actions for any issues. Less pest pressure than pot culture.
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Weed control – Keep planting area free of encroaching grass/weeds which compete for resources.
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Mulching – Replenish mulch layer to conserve moisture and suppress weeds.
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Digging – Carefully dig up and pot into bonsai containers once goals are achieved. Root prune excess growth.
With attentive care and patience through each step, ground growing can be a valuable technique for creating bonsai specimens with impressive trunks and roots.
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Bonsaify | The One Mistake All Bonsai Beginners Make: Here’s How to Avoid It!
FAQ
Can I plant a bonsai tree in regular soil?
Using regular potting soil for bonsai trees is generally not recommended. Regular potting soil tends to retain too much moisture and can become compacted, which can lead to root rot and poor aeration. Instead, it’s better to use a specialized bonsai soil mix that provides good drainage and aeration.
What is the rule of 3 in bonsai?
Here’s the general rule to follow: Build the structure of a bonsai by laying out its branches beginning with three principal branches. These are the first branch, the second and the third. One of them — the second or the third — will be placed at the rear.
What happens if you don’t trim a bonsai tree?
If you don’t trim a bonsai tree, several things can occur: Overgrowth: The tree may grow excessively, losing its compact shape. Without regular pruning, branches can become long and unruly, making it difficult to maintain the desired aesthetic. Health Issues: Untrimmed trees can develop health problems.
How long can a bonsai tree stay in a box?
How long is the bonsai okay in the box? All bonsai are soaked prior to dispatch to ensure that the do not dry out during transit. In our experience, this means the bonsai should be fine in the box for 2-3 days after delivery.
Can a bonsai grow in the ground?
If you plant a bonsai in the soil, it can easily grow out of control, turning into a full-sized tree. The best way to grow a bonsai in the ground is to start it from a seedling, which has an extremely thin trunk. When it comes to planting bonsai in the ground, it’s important to remember that your bonsai’s roots need to have ample space to grow.
How to plant a bonsai tree?
You may choose to plant a bonsai seed in the ground or plant a smaller bonsai tree. A seed of a young bonsai tree stands a chance to grow a full root system and later extend to a big tree. If you choose a mature tree, it’s unlikely to grow larger roots because it has reached its maximum length.
Can a bonsai tree grow out of control?
This can help you avoid mistakes that can lead to your tree growing out of control. If you plant a bonsai in the soil, it can easily grow out of control, turning into a full-sized tree. The best way to grow a bonsai in the ground is to start it from a seedling, which has an extremely thin trunk.
Can a bonsai tree grow from a seed?
A seed of a young bonsai tree stands a chance to grow a full root system and later extend to a big tree. If you choose a mature tree, it’s unlikely to grow larger roots because it has reached its maximum length. A potted bonsai, when transplanted in the ground, has low chances of recovery.
How do bonsai trees grow in Japan?
In Japan you will often see bonsai trees grown in the ground in a mound. Instead of building a grow bed structure to place the soil in, they just mound up the soil and place the trees into this mound. It’s the exact same as a grow bed, just without the retaining walls.
Will a bonsai grow into a full size tree?
A bonsai will try to grow in to full size tree if you let it. One of the main reasons a bonsai stays so small is due to the limited growing space they have in a small pot. Once you plant a tree in the ground this space restriction is removed and they will quickly start to stretch out and take advantage of the endless room available to them.