Basic Bonsai Care

Watering

• Check your tree daily. Pick up the pot and learn how heavy it feels when fully saturated vs. barely damp.

• Water when the pot feels damp, but is not saturated. The weight of the tree is your best indicator, but if the surface is continuously drying before the soil, a very light water or mist can keep the surface moist without constantly soaking the roots. 

• Trees grow outside, it rains outside. When we water, we water thoroughly like rain until water drains freely from the bottom of the pot, wait a few minutes, and repeat that a few times. We want the soil fully saturated after watering.

• Don't keep the soil constantly soggy, allow them to dry slightly between waterings. Roots need both water and oxygen. This is particularly important for freshly potted/repotted bonsai. 

• During hot, dry Missouri summers, expect to water daily, sometimes twice a day for small pots or thirsty, well established species.

• There is no perfect watering schedule.

Check the tree, not the clock.​

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Light

Outdoor / Cold-Hardy Bonsai

• Maples, elms, junipers, pines, bald cypress and other temperate trees belong outside year-round.

• Around 6 hours of direct or slightly dappled sunlight morning through early-afternoon sun is ideal for most deciduous species.

• Pines, junipers and other sun-loving species may prefer direct sun most or all of the day, but during the hottest season they too can benefit from afternoon shade.

• Afternoon shade can reduce heat stress and watering during our hottest summer weather. 

• Outdoor bonsai cannot be kept indoors as houseplants. They need the changing seasons and winter dormancy. 

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Sun grows trees. Shade merely spares them.

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Indoor / Tropical Bonsai

• Ficus, dwarf jade, and other tropicals can survive indoors, but generally thrive outside during warm weather.

• Move them outside once nights are consistently above about 50°F.

• Gradually introduce trees coming from indoors to direct sun to prevent leaf burn. A few days with an hour or two of morning sun is sufficient. 

• Bring them back inside before fall nights regularly drop below about 50°F.

• Indoors, place them in your brightest window. Grow lights are a great way to supplement out short days during winter, but if it doesn't hurt to look at its probably not doing much.

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A label that reads "Bright indirect light" is lying.

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Feeding

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• Fertilize during active growth, generally spring through early fall.

• A general-purpose balanced fertilizer works well for most bonsai, but don't confuse slow release for controlled release such as Osmocote®. 

• Use approximately 0.5x to the 1x the labeled rate. Some species prefer stronger fertilizer, do some research.

• More fertilizer isn't always better. Don't try to fertilize a stressed or unhealthy tree back to health.

• Tropical trees actively growing indoors under good light can be fertilized lightly during winter. Its generally unnecessary for dormant outdoor trees.

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Starvation is not refinement.

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Pruning

• Bonsai development is a cycle of letting the tree grow, then cutting it back.

• Light trimming can be done throughout the growing season on healthy trees.

• Larger structural cuts are generally best done in early spring, summer, or fall, depending on species. Many pines and junipers tolerate heavy winter work. 

• Tropicals generally tolerate heavy pruning year-round as long as they are growing vigorously. ​

Growth makes branches. Cuts make bonsai.

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Wiring & Styling

• Wire generally isn't left permanently, its used to shape branches and trunks for more control of the style.

• Wrap wire around the branch, not the branch around the wire. 

• Keep all wires wrapped in the same direction at ~45°. Don't wrap one wire clockwise and the other counter-clockwise or you'll risk choking the tree.

• Check wired branches every week or two during active growth. Remove wire as soon as you see signs of swelling/biting into the bark.

• Fast-growing trees can thicken around wire surprisingly quickly. Branches of cold hardy trees may take all winter and some of spring to set. 

Let the branch remember, not the bark.

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Repotting

• Most bonsai need repotting roughly every 2–5 years, depending on species, age and growth rate. If the soil becomes very compacted and begins draining poorly, it may be time for a repot.

• For most outdoor bonsai, late winter/early spring just before or as the tree begins waking up is the ideal time. After major root work, protect the roots from hard freezes.

• Tropical bonsai can be repotted year round, but are generally best repotted during warm, active growth.

• Repotting doesn't necessarily mean using a larger pot. Bonsai are often root-pruned and returned to the same container. It may also mean

• Minor root work ~10% can be done on most healthy trees year round without too much risk. 

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Impatience kills more roots than neglect.

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Winter Care

Outdoor / Cold-Hardy Bonsai

• Keep them outside but protected. Cold-hardy trees need winter dormancy to survive long-term.

• Bonsai roots are less cold-hardy in a pot than the same tree growing in the ground.

• Before major freezes ~25-30°F, place pots on the ground and out of harsh winter wind.

• Mulch over and around the pots with leaves, pine bark, wood chips, etc. for additional protection.

• Frost blankets or an unheated garage/shed can provide additional protection during extreme cold.

• If overwintering in a structure, aim to keep dormant trees roughly 28–40°F. Too many days above ~40-50°F can wake them prematurely.

• Dormant trees still need occasional water. Don't allow the root ball to completely dry out. When exposed to rain/snow, this is rare in our region but its prudent to check every 2-3 weeks. 

Cold is not the enemy. Extremes are.

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Indoor / Tropical Bonsai

• Tropical bonsai cannot survive a Missouri winter outdoors. Most tropicals start experiencing mild stress/dormancy below ~60°F, more serious stress below ~50°F, and extreme stress or death below freezing.  

• Bring them inside when nights begin falling below about 50°F. One or two nights at 40-50°F is no big deal, a week of cold nights will start stressing them significantly. 

• Keep them in the brightest window available or use a grow light (refer to the Light section)

• They will often use less water indoors as their growth slows, so check the soil rather than continuing your summer schedule.

• Keep them away from cold drafts and hot, dry heating vents. For some species such as Serissa, they prefer a little "cool down", so a cooler/drafty window is preferred.

• Some leaf drop after moving indoors is normal while the tree adjusts. Some trees are notorious for dropping leaves when brought indoors such as Ficus.

Winter asks for less, not nothing.

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*Note, subtropical and species that are semi-cold hardy (zone 7+) in our area are more difficult to overwinter in our zone 5/6 winters. We generally don't recommend such species for beginners. 

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Remember the Big Three

If you remember nothing else:

• Water based on the soil, not a schedule.

• Outdoor/cold-hardy bonsai stay outside year-round and need winter dormancy.

• Indoor/tropical bonsai go outside for summer and come inside for Missouri winters.

Get those things right and you've already avoided most of the mistakes that kill beginner bonsai. And dont forget to have fun!​​