Basic Bonsai Care (Hardy types)

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Caring for bonsai is almost like caring for a pet-bonsai do require a bit of attention and care to be successful, but they are worth it for the serenity and beauty they bring to your surroundings.

Dwarf Zelkova as bonsai, approx. 20 years old

Dwarf Zelkova as bonsai, approx. 20 years old

True bonsai masters spend decades perfecting their craft...this information is very basic and covers how to take care of a young bonsai you have purchased. We recommend further research if you choose to take up bonsai as a serious hobby-it is a fascinating subject!

Light

Light needs for hardy bonsai are similar to the non-bonsai versions. For example, an azalea bonsai would prefer bright shade, while a spruce bonsai would prefer more sun. Providing the maximum amount of sun that the particular type of plant can tolerate will help keep growth compact. That being said, in summer it can be beneficial to protect even sun-loving varieties from the hottest mid-day sun. It makes keeping up with watering that time of year a bit easier also.

Watering & Fertilizing Hardy Bonsai

The most critical part of bonsai care (next to pruning…) is watering. Bonsai support a relatively large plant for the container size and soil volume. Your bonsai may need to be watered once a day or more in hot weather. Check the soil regularly to learn how quickly it dries out.

When you water, be sure to soak the soil thoroughly until water runs through. Once the soil is watered well, be sure to tip out any standing water from the saucer, particularly if the saucer is attached. If your bonsai is very tightly rooted it can be helpful to water by soaking in a bucket for a few minutes until bubbles stop rising.

Bonsai should be fertilized during the regular growing season. You can use a liquid fertilizer or a slow release fertilizer applied according to package directions. Select a higher nitrogen fertilizer early in the season (spring) to encourage growth, a balanced fertilizer in summer, and a low nitrogen fertilizer in fall to prepare the plant for winter.

Winter Care

Your hardy bonsai should remain outdoors in winter with some protection. The small volume of soil is susceptible to repeated freeze/thaw cycles that should be minimized, and the soil is prone to drying out which can lead to winter-burn. A cold greenhouse or a cold frame is ideal for overwintering bonsai, but most people do not have that luxury. Alternately, the pots can be sunk in the ground and mulched to minimize temperature swings (don’t let mulch contact the plant). Check for water regularly, particularly when severe cold is forecast. Burlap or frost-protective fabric can be used temporarily during cold snaps also-be sure to remove once the weather warms.

Repotting

(This is very basic bonsai repotting information-the art of repotting bonsai is much more involved. If you really want to get into detail, search YouTube for “bonsai repotting”)

Check the roots of your bonsai at least once a year in early spring, preferably before new growth begins.  You may need to remove any wire securing the plant to the pot. Because of the shape of many bonsai pots, you may need to cut the root ball around the edges with a sharp knife to get it out of the pot. If you see roots are starting to circle the container, your bonsai will need repotting. Always repot in spring to allow the rest of the growing season to recover.

Gently remove most of the soil until you can clearly see the roots. Look for rotted roots (can happen when your soil probably holds too much water, or you water too frequently), or roots longer than the container can hold (this is when they start circling). These will have to be removed.

Once roots are trimmed where needed, place the bonsai back in the pot. Gently wire into place using copper wire, and fill with soil. Chopsticks can be very handy to gently push soil between roots to avoid air pockets. Water thoroughly, but do not fertilize for a month after repotting.

An ideal potting mix drains well yet has some organic material for nutrient and water holding capability. A mix of Turface or soil conditioner, fine gravel and a quality potting soil at about a 1:1:2 ratio is a good start, and can be adjusted to hold more water (add potting soil) or less water (add more fine gravel) depending on specific plant needs.

Pruning

Chinese juniper bonsai, over 250 years old.

Chinese juniper bonsai, over 250 years old.

(Again, this information is very basic. Search YouTube for “pruning bonsai” for detailed instructions and advanced pruning techniques.)

Pruning is a very important aspect of bonsai care. Without regular pruning, your bonsai will not remain a bonsai for long!

In simple terms, prune your bonsai whenever it has outgrown its shape. This can be done at any time in the growing season. For deciduous types, snip off whatever “sticks out”, using standard pruning techniques for placement of cuts. For evergreens, gently pinch out the growth that is too large, or use very small, sharp scissors to remove growth. Be precise when pruning evergreens, as surrounding needles will brown if damaged or cut.

Image credits:
Chinese juniper by Peter coxhead (Own work) [CC0], via Wikimedia Commons
Dwarf Zelkova by Tangopaso (Own work) [Public domain], via Wikimedia Commons