SUStee Water Meter

R99 - R195


SUStee is a ‘watering checker’ that can tell you when to water your plant by changing its colour. Just stick this fail-proof device in your plant pot, and you’ll be at ease for quenching your plants’ thirst. One SUStee per pot takes away all your troubles. No batteries needed.

SUStee’s inner core is 100% natural, made from non-woven cotton, and can be easily replaced. Depending on the type of soil used, the inner core has a life span of 6 to 24 months. SUStee’s body is made from durable, high quality polycarbonate.

Easy to use and award winning

The first moisture checker with pF indicator for your home

For the first time ever, a home-grade moisture checker has been equipped with a pF indicator (available water capacity). This way the root's ability to absorb water - or the plant's "thirst" becomes visible (patented in Japan, No. 5692826). The high quality of SUSTEE prevents root rot caused by improper watering. To better our product we keep testing and researching in cooperation with the Tokyo University of Agriculture and farmers.

Incorrect watering is reported to be the cause of plant wilting 80% of the time

Plants wilter because they are not thoroughly watered. However, too much water leads to root rot more often than you would think. Japanese farmers say that "it takes three years to learn watering plants properly", this goes to show, that even professionals struggle.

Many people mistakenly believe that there are different watering frequencies for different plants

Watering timing varies depending on multiple factors, such as temperature, humidity, season or the growth status of a plant, etc. . The environment – not the type of plant – determines the right time for watering.

There is a beneficial soil moisture range shared by all plants

It is called “available water capacity”, which works as a common denominator for moisture management for all plants, preventing them from root rot and drying up. SUStee helps you water the right way to maintain this beneficial moisture range.

The beneficial moisture range can be rated using what is academically called pF value.

PF-value is a term often used in agricultural colleges and by commercial farmers. The values are measured using a device called a pF meter (pF stands for “potential force”). Adequate plant watering for any plant is ensured when the pF-value range between 1.7 and 2.3 is observed. SUStee is designed to gradually start turning from blue to white at about pF 2.0, the median value of the range, and will turn completely white at about pF 2.3, which is the perfect time for watering.


How it works?

Color change tells you the right time to water. Just stick in and leave in the pot. No batteries needed.  


Everything about pF-value

“pF” stands for “potential force” and describes the effort it takes the plants’ roots to extract water from the soil.

“High pF-value” means that it takes the plant a lot of effort to extract water, which in turn suggests that the soil is rather dry and the plant struggles to extract water.

“Low pF-value” means that the plant can extract water easily, which in turn suggests that the soil is wet and the plants’ roots are submerged in water and unable to breath.

There is a “pF-value” spectrum which is good for all plants. In other words: there is a quantity of water that is suitable for every plant, enabling it to extract water stress free. This is called the “ideal moisture level”.

SUSTEE is designed to start changing its colour from white to blue at a pF-value of 2.0, which is the middle value of the “ideal moisture level”. Sustee will turn completely white at a pF-value of 2.3, which is the upper level of the “ideal moisture level” and the perfect moment to water your plants to grow strong and healthy.


how SUStee works


  • SUStee is the only moisture checker for home use based on pF value (available water capacity). Professionals measure the pF value with expensive devices, but with SUStee you can become a professional too.
  • SUStee senses water at root level, no dirty fingers, damaged roots and disturbed top soil by trying to gauge moist soil by feel.
  • Simple to use: leave the device in the pot to continuously monitor soil humidity and show you when to water your plants. SUStee will turn from blue to white when your plant needs to be watered.
  • Suitable for all kinds of plants and all kinds of soils - suitable for indoor and outdoor plants.
  • SUStee’s award winning design is simple and minimalistic so it doesn’t take away from the beauty of your plants.
  • SUStee needs no batteries and is environmentally friendly. SUStee’s inner core can be manually replaced. Depending on the type of soil used, the inner core has a life span of 6 to 24 months.
  • Developed, designed and made in Japan, in collaboration with Tokyo University of Agriculture and farmers to improve the design and function of each stick. SUStee is the result of more than 8 years of research.
  • Winner of numerous design awards and made with High Quality Polycarbonate.
  • Environmentally friendly and economical - The inner core of SUSTEE is made of natural fibers and can be consumed by microorganisms

awards for SUStee


Available in S, M and L to fit different pot sizes:

  • Small Pen (12cm) suitable for pot sizes Diameter 6-9 cm
  • Medium Pen (18cm) suitable for pot sizes Diameter 10.5-18 cm
  • Large Pen (25.5cm) suitable for pot sizes Diameter 18 - 65 cm

How to use

Step 1: Set

  • Insert SUStee into the soil at the base of the potted plant until the “Ω” marking is covered or to the depth between the “▶︎” “◀︎”marks on the meter.
  • SUStee should sense moisture around the plant’s roots at the bottom of the pot, so it needs to be placed close to the plant itself, within a 20 cm radius.
  • For SUStee to work properly it is important that the bottom opening is completely covered in soil and the upper opening is out of the soil.
  • Eventually, the soil in the pot may settle, so it is important to regularly monitor the position of the bottom opening and, if it is no longer covered with soil, push the SUStee deeper.

Step 2: Water

  • Remember to water generously when you use SUStee for the first time.
  • SUStee will change its colour from white to blue within 20-30 minutes depending on the amount of water given and the water retention level.
  • The periods given below are only rough guides and with some soils it can take up to an hour.
  • Size S: Approx. 3 minutes
  • Size M: Approx. 15 minutes
  • Size L: Approx. 25 minutes

Step 3: Monitor

  • Simple to use: leave the device in the pot to continuously monitor soil humidity and show you when to water your plant.
  • The time for watering your plant has come when the little window on SUStee’s top has turned completely white.
  • Blue → the soil is adequately hydrated, no additional water is required.
  • White → the soil is dry and watering is required.
  • We do not recommend watering if SUStee shows the slightest hint of blue. Wait until it turns completely white.

The Inner Core

The inner core of SUStee is 100% natural, made of non-woven cotton and will be consumed by microorganisms over time. 

The state of the soil is a factor, but it can be said that the core has to be replaced when it stops turning blue after watering (approximately after 6-24 months).

Approximate inner core replacement times for different soil types

  • Organic culture soil: 6 to 9 months
  • Inorganic soil: 9 to 12 months
  • Hydroculture: 1 to 2 years
  • Bog moss/bark: 1 to 2 years
  • Peat moss: 1 year

We guarantee that the inner core will last at least 6 months.

Changing the core is done in 2 steps

SUStee Innercore change

It is easy and can be done by anyone.

Step 1

Remove SUStee from the pot and follow the instructions below. If dirt has accumulated inside SUStee clean it before you insert a new core.

Step 2

Remove the lock cap by turning it counterclockwise. Take out the used inner core and replace it with a new one.

Watch out for:

Make sure you replace all components in a single operation:

  1. Inner core
  2. Blue sheet
  3. Transparent straw around the blue sheet

It is rare but possible that the transparent straw is left behind inside the main unit. If this happens, simply remove it with a pair of tweezers.

Remove the top screw cap and look inside to make sure none of the used core material is left behind.

Keep the refill in the inner bag of the product package until just before use. Once taken out of the bag, the refill’s core material may discolour.



How much water should I use?

Always water your plants thoroughly. The correct amount of water is equal to a fifth to a quarter of whatever volume your pot holds. Try to water evenly.

How do you know when to replace the inner core?

  1. Take the SUStee device out and verify the opening at the bottom. If the inner core has decomposed, it is time to replace it with a new one.
  2. The inner core should be replaced when the device stops reacting, even if it is not entirely gone.

After long time use, the device might react poorly due to soil components or other fine particles deposited onto it.

How to take care of SUStee?

After long periods of use SUStee might not react as swiftly as it should. This may be due to soil sticking to it. Mix neutral detergent with warm water and place SUStee upside down (the window facing downwards) and let it soak for about an hour. Whatever is sticking to SUSTtee should come off and dissolve this way. After cleaning let SUStee dry till it shows white before using it again.

What if my SUStee arrives and my indoor plant is already watered?

Simply prime your new SUStee by placing it into a cup of water and wait until the window turns blue. Then place it into your already watered plant.

Is SUStee affected by water sprayers or rain?

No. SUStee registers the amount of water in the soil. If the product gets wet and changes its colour to blue, it will turn white again, as soon as the soil is dry.

Does the use of inorganic fertilizers, organic fertilizers, pesticides, etc. affect the product?

Unless used in excess or if the product contains a lot of oil, it should not affect SUStee.

Will the change of colour alter with the seasons?

Yes. During hot summers water in a pot will evaporate much quicker, leading SUStee to turn white much quicker than in spring or autumn. In winter however, water will evaporate slower, which will result in SUStee staying blue for longer periods than in spring or autumn. With SUStee you will see that the appropriate time to water your plants will change with the seasons.

What to do if SUStee does not change colour?

One of the following may be hindering water supply:

1. First time use

Not enough water was given. When using SUStee for the first time, please water generously after inserting it in the pot until water drips out into the saucer. However, excess water in the saucer must be avoided afterwards.
Colour indication may work better if SUStee is inserted into the pot soil before watering, as the device is constructed in such a way that its core will soak up water through capillary effect and change colour.

2. SUStee is in poor condition

SUStee has a hole at its bottom for soaking up moisture. If it gets clogged with old soil, excess roots of a root-bound plant or dirt with extremely high viscosity, SUStee may no longer absorb water. This can be improved by loosening the soil before inserting the SUStee device or finding a new spot for its insertion.
If your SUStee was used for more than 6 months it might be time to replace it. Be environmentally friendly and replace only its inner core.

3. Water drains too well to be absorbed

SUStee has a hole at its bottom for soaking up moisture. Water may drain too quickly in extremely grainy earth for SUStee to absorb, resulting in no colour change. This may be improved by pouring water mindfully over the bottom of the SUStee device when watering the plant.