March 14, 2021

How Much Sunshine Does A Bonsai Tree Need

While bonsai trees are hardy plants, maybe temperomental plants, this doesn’t necessarily mean they love the heat.

So how much sunshine does a bonsai tree need? Direct sunshine is fine providing it isn’t too hot or your bonsai will burn. Indirect bright shade is best.

Let’s discover how you can create this bright shade and look at other factors like how your bonsai tree is stored, the amount of water and the early signs that the sunshine in your area is doing more harm than good.

Containers vs. Pots

Most of my bonsai trees are in small pots. In summer the water in the pots dries out quickly, sometimes in a day or two, and my bonsais are left bone dry.

As you can imagine, when the 35C/100 F degree weather sets in, it doesn’t take long for the leaves to heat up and dry out or burn, especially if they are in direct sunlight.

Direct Sun vs. Bright Shade

My Bbonsai collection is on the rear side of my house so it gets direct sunlight from sunrise until about 3:00 in the afternoon. That is a lot of direct sunlight!

When the temperatures get above 32C, I’ve found I need to water my plants every other day to keep the roots cool and the leaves plump.

Despite this frequent watering, the bonsai leaves still get hot and I’ve had some but pretty badly. The intense light in combination with high temperatures can be brutal.

If you gradually introduce your bonsai trees to the direct sunlight (increasing an hour or so every couple of days), most bonsais will tolerate full sun most of the day.

I recently added some shade cloth to protect them from the direct sunlight. I also moved some of them under an outside stair well, creating another form of shade. While the outside temperature is still above 32C, the area surrounding the bonsai trees is much cooler from the shade cloth.

And, without direct light shining on the plants the leaves don’t get as hot and are unlikely to sunburn or show signs of too much heat.

Some bonsais, such as fig bonsais, prefer bright indirect sunlight all day. On the other hand most desert rose bonsai can handle direct sunlight with no shade during the day. This is why it’s important to know what types of bonsai you own.

An interesting side affect of direct sunlight on some bonsais is called “blushing” – the leaves will change colour.

Another great option is to simply place your bonsai trees in an area (like my stair well) that gets bright shade for most of the day. Ideally, they’ll be in an area with an hour or two of morning sun, but then shaded the rest of the day.

Since the temperatures are generally higher in the afternoon, direct sunlight during this time can be problematic. Morning sun, on the other hand, is cooler and less likely to cause sunburn.

Extreme heat can be very problematic for a lot of bonsai trees. While people think of bonsais as hardy, resilient plants, they don’t all grow well in an extremely hot desert climate.

Water in the Soil

While bonsai trees don’t like to sit in very wet soil, they are much less likely to suffer in intense heat if the ground is slightly wet or freshly watered. This helps keep the roots and therefore the rest of the plant cooler.

Age and Size of the Bonsai Tree

The larger a bonsai is, the less likely it will be affected by hot temperatures.

A large plant is much stronger, has a deeper root system, and has likely had time to adjust to the warmer temperatures. While it’s still possible for them to sunburn (especially if moved from shade to sun), it isn’t as common.

Newly planted bonsais and fresh cuttings will need a lot of extra attention if planted outdoors. They will need to be eased into the heat gradually. If left in 32C+ degree weather (or warmer) for too long, it’s likely they will quickly burn and die.

Signs of Too Much Heat and Sun

It doesn’t take long for bonsai trees to start showing if they are stressed from too much heat or direct sunlight. Do bonsai trees need direct sunlight?

When bonsais are getting the right amount of sun they’ll often “blush” or change colors. This is such a beautiful transformation to see!

If they start to get too much sun however the leaves will actually burn. You may begin to notice white or pale patches on the bonsai leaves. This damage cannot be reversed.

Instead, try to move your plant to an area with less hot, direct sunlight and wait for new leaves to grow. If only one or two leaves are damaged you can remove them, but it’s not necessary.

In some cases the leaves will actually turn dry and black. The black will start on the outside edges of the leaves and will be dry and crispy (in contrast to blackening from rot which starts in the middle of the plant and is wet and mushy).

Again, this damage will not heal but will remain until the leaf completely dies and new leaves form.

If a bonsai tree is in the shade but still experiencing really hot temperatures you may notice a golden/yellow color start to appear. The bonsai doesn’t turn completely yellow/brown like it would with sunburn, instead the colours tend to look warmer or more yellow than usual.

This generally goes away, or the bonsai will revert back to it’s original color, if the bonsai is moved to a cooler environment.

Conclusion

To summarize how much sunshine a bonsai tree needs, firstly you must know your bonsai tree and which one best suits your climate. Keeping you bonsai outdoors  encourages strong growth, but for most bonsais do not place them in direct sunlight.

Insread place them in an area with bright shade. Use a cover like a shade cloth to defend off the harsh sun especially if the temperatures go over 35C.

Keep an eye of their water as bonsai trees tend to dry faster on hot days. Apply commonsense when it comes to direct sunlight and your bonsai trees will thrive.

 

About the author 

Greg Reed

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