Arguably, one of the most important tasks to ensuring your bonsai tree stays healthy and grows appropriately, is watering. It is hard to quantify exactly how often your tree will need to be watered because there are so many factors that could easily alter the amount and frequency of watering your tree will require to not only survive, but also thrive in its container. Let’s consider a few crucial factors that may help you better determine your bonsai’s watering needs.

Climate and Season

One of the first things to consider when determining your bonsai’s watering needs is to ask the question: what type of climate does your tree live in? Is your bonsai exposed to rain every day or does it experience long days (or weeks) with out even a hint of moisture in the air? Over watering may not be equally as detrimental to the health of your bonsai as is completely depriving your tree of water altogether, but it is certainly something you want to avoid.

Given the confined nature of bonsai pots and often times, the sever lack of organic material used in the soil (more on this below), it is vitally important to not allow your tree to completely dry out in between the times that you water it. This means that if your tree lives in a dry climate that you may even want to water your tree more than once a day, thoroughly soaking the soil and foliage each time. A good rule of thumb is to test the surface of the soil with your finger before you water it. The soil should be slightly wet to the touch and not totally dried out.

Similarly to climate, is is also important to understand the seasons and whether or not your bonsai tree is actively growing or is in a dormant state. It may go without saying, but your trees will require less water during the dormant period (early fall-late winter) and more water when they are growing (early spring – late summer). Unless you’re in the Pacific North West, like we are, then just get an onslaught of water all year around.

Soil content

This brings us to your tree’s soil mixture. The contents of bonsai soil can greatly effect the amount of water your tree is able to absorb each time you water it. If the soil is poor (like garden soil with a high clay content) the water will not be able to fully penetrate and saturate the soil and will most likely not be able to reach all of the tree’s roots. This can be avoided using a mixture of akadama, pumice, and lava rock, which offers great drainage and water retention. For a more extensive understanding soil mixtures, click here.

Another thing that can greatly prohibit your bonsai’s ability to absorb water is overgrown roots. Growing trees need to be regularly repotted to ensure the tree’s roots do not become overcrowded in the container and prevent proper drainage. For more on this topic, read our article on repotting here.

Best time of day to water?

In general, it does not really matter what time of day you water your trees. That part really comes down to when you have the ability to do so. However, it is important to note that broadly watering all of your trees on a schedule in not the ideal method to gain a specific understanding of each individual tree’s health and needs. Even the trees are the same species, it is important observe the tree’s needs on an individual basis and respond accordingly. If you are too overly broad with your water cycle, it may be easier to overlook some telltale signs that a tree is note being watered correctly.

Techniques for proper watering

There are really two primary ways to water your bonsai trees: top watering and soaking.

Soaking can be an effective, though, time consuming, way to water your trees, but it’s not really a viable option for larger bonsai. The basics for this method are to place the bonsai in a tub of water, but don’t fully submerge the entire container. The water will absorb into the soil primarily through the drainage holes on the bottom of the pot. The soil will be thoroughly saturated when the surface soil is damp and then you can remove the tree from the tub.

Top water is probably the most popular way to water bonsai. Using a fine nozzle on a watering can or hose, water the top of the soil thoroughly unlit water begins to drain for the drainage holes underneath. depending on the size of the tree and container, this may have to be done several times to real all of the trees roots.