Watering Your Bonsai While On Vacation


If you want to go on a vacation but you do not know how to water your bonsai trees, here is how.

While you are away, use a box filled with sand and bury the bottom of the bonsai pots in it to increase the amount of soil that the bonsai trees can access. 

How to water bonsai while you are on vacation

Bonsai watering system

While you are away, you can use a box filled with sand and bury the bottom of the bonsai pots in it.  The concept of this bonsai watering system is to increase the amount of soil to hold more water without repotting the bonsai trees to bigger pots and to get rid of it easily when it becomes unnecessary.

Put the system in place and try it a week or two weeks before you go on a vacation to see if it works properly.  Also, check the weather forecast for the days you are away and make necessary changes to the watering system accordingly.

Bonsai watering system while on vacation

Here are step-by-step instructions on how to prepare the bonsai watering system while you are on vacation.

  1. Prepare a box with a height below your bonsai pots’ depth.
  2. Cover the floor of the box with waterproof material.
  3. Fill the box with sand/perlite/vermiculite.
  4. Connect a hose coming from a tap to an automated water timer and put the hose in the box to feed water.
  5. Bury the bottom of the bonsai pots in the box.
  6. Fill the box with water before you go on a vacation.

The box

type of the box

The material of the box could be anything from wood to plastic.  Anything you can find at home which can hold sand, as well as your bonsai trees, will do.

Height of the box

The height of the box should be below the pots’ height so that the soil can dry with wind and sunlight at the same time as it retains water.  Too much water could rot the roots of your bonsai trees.

Waterproof material at the bottom

Covering the bottom of the box with waterproof material such as plastic/vinyl sheets will increase water retention.  It might be a good idea to have some kind of holes at the bottom of the box to drain water, depending on the weather condition.  Without drainage holes, the box could be flooded with water when it rains heavily.

If you live in a rainy, humid region where the soil does not dry out quickly, you might not need to cover the bottom of the box with waterproof material.  The sand in the box will be all you need.

The sand

Type of the sand

Hoffman Lava Rock

(Link to Amazon)

The type of sand in the box could be anything that you can find at home or in gardening shops.  Volcanic lava rock you can buy from Amazon works perfectly.  You can also use perlite or vermiculite if they are readily available to you.  Use something that holds water adequately but drains it sufficiently as well.

Using ordinary potting soil is not advisable as it does not drain water enough for bonsai trees.

To know more about the types of sand used in bonsai, please read the following post.

“Is sand food for bonsai?” (Link here)
Amount of sand

The sand in the box should be at least 2 inches (3cm) deep to keep enough moisture for some time.

Automatic water timers

Automatic Water Timer

(Link to Amazon)

Depending on the weather and how long you are away, you might need an automatic water timer to feed water to the box like this you can buy from Amazon.   By using this, you can set the watering frequency from 10 seconds to once a week and the duration up to 6 hours.  It has a rain delay feature as well that enables you to not be bothered by the rain.

Make sure to feed the water to the sand in the box.  The concept of this bonsai watering system is to increase the amount of soil to hold more water, not to water your bonsai trees directly.

How much or often you have to water depends on the weather, temperature, days you are away, and the species of your bonsai trees, as well as the amount of sand in the box.  So, if you are going away for more than a few days, you might want to try this watering system and determine the right settings for the automatic water timer.

How to put the pots

You only have to bury the bottom of the pots to feed the water to your bonsai trees.  Remember that the soil has to dry with wind and sunlight at the same time as it retains water.  For big pots more than a foot high, too much or too little water will kill the tree; retaining a good balance is important.

Before you go on holiday, fill the box with water to make sure your bonsai trees are fed with water for a few days.

How long can I leave a bonsai without water?

Under a temperate climate, a bonsai tree can go without water for one day in summer and three days in winter if planted in an ordinary bonsai soil mix.  Frequency of watering depends on the climate, weather, and age/species of the bonsai trees.

Can a bonsai go a week without water?

A bonsai tree cannot go a full week without water.  Bonsai trees are planted in a very limited amount of well-drained soil and so leaving them a week without water will almost certainly kill them.

Shallow pot

pot size balance to the tree

A bonsai tree is planted in a tiny, shallow pot that can hold a very small amount of soil.  The pot depth depends on several factors such as the style of the tree and how you want to represent the tree with the pot.  But in any case, bonsai pots are a way shallower than normal planting pots.

Well-drained soil

Akadama and Kanuma soil

As to the bonsai soil, recommended bonsai soil mix does not hold water as well as the normal potting soil.  Bonsai soil requires good water retention as well as good drainage.  Without good drainage, the root system that is packed in a tiny pot might rot with water.

Also, bonsai soil mix should contain little or no organic matter which enables the soil to hold water well.  The nutrients should be added at an appropriate timing as fertilizer to control the strength of growth to style the tree we want.

If you are interested in learning more about bonsai soil, the following post might be helpful.

“Every soil you can use for bonsai explained” (Link here)

How often should a bonsai be watered?

Watering bonsai trees

Under a temperate climate, you should water your bonsai tree;

  • once a day in spring and fall,
  • twice a day in summer, and,
  • once every three days in winter.

Of course, the frequency of watering should be adjusted where your bonsai tree is placed.  The point is to water them when the soil is half dry.

Factors affecting the frequency of watering

The frequency of watering your bonsai tree depends on several factors as follows:

  • Frequency of the rain in the region,
  • Temperature,
  • Amount of sunlight,
  • Age of the tree (the younger, the more water),
  • Species of the tree (flower and fruit bonsai need more water than coniferous bonsai), and,
  • When it is last repotted (the longer, the more water retention due to the development of the roots).

If you live in a hot, dry region and your bonsai tree is a young flowering tree, you might want to water your tree several times a day in summer.  But if you live in a hot but humid climate and your bonsai tree is a spruce, you might have to water your tree once a day or once every 2 days in summer.

Should you leave bonsai sitting in a water tray?

You might think to put your bonsai tree in a water tray to hydrate it but it is not advisable.  You should not leave a bonsai tree sitting in a water tray because it might cause the root system to rot. 

The roots of a bonsai tree are confined to a very small pot but they need to breathe as humans do.  Roots inhale oxygen to burn carbohydrates for their energy to grow and repair.  If you leave your bonsai tree sitting in a water tray, the roots will drown in water which will kill them eventually.

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