Over time, SUStee might become a little less responsive. Don’t worry—this usually happens when tiny particles in the soil clog the filter.

Here’s how to refresh it:

1. Take SUStee out of the soil and turn it upside down (the little window should face down).
2. Place it in a cup of hot water and add a few drops of mild dish soap.
3. Let it soak for about 1 hour. You’ll notice the built-up residue start to dissolve.
4. After soaking, dry it completely until the indicator turns white again.

Once unclogged, your SUStee will be ready to use again—just like new!

SUStee works with most plants grown in soils that hold some moisture—like peat moss, coco peat, vermiculite, akadama soil, potting mix, black soil, sphagnum moss, and bark.

It’s also great for:

• Hydroculture & semi-hydro setups
• Planters and pots
• Self-watering systems for veggies
• Outdoor gardens and beds

Basically, if your soil retains water, SUStee can help! 🌿
(Just a note: soils that contain lots of oils or sticky components may clog SUStee faster, so you might need to clean it from time to time.)

For the most accurate reading, SUStee should be placed near the roots, where your plant actually drinks water.

👉 Simply stick it into the soil within about 20 cm (8 inches) from the base of your plant.
This way, SUStee can monitor the moisture right where it matters most!

Yes, it can!
All plants share what’s called an “optimal moisture zone”—a range of soil moisture where they can grow strong and healthy. Within this zone, plants are less likely to suffer from root rot (too much water) or wilting (too little water).

SUStee is designed to measure this zone and let you know the right time to water. (In fact, this technology is patented ).

We developed SUStee together with professional growers, and it’s been highly rated by them for its reliability.
👉 Curious to learn more? Check out [What is SUStee].

It’s easy!
When the SUStee indicator window turns completely white, it’s time to water your plant.

A good rule of thumb is to water with about one-fourth to one-fifth of the pot’s volume.
Make sure to pour it evenly so the whole potting soil gets moisture.

• Don’t worry—there are a few possible reasons, and most are easy to fix!

  1. First time use (brand new SUStee)
     When you first open and use SUStee, water your plant thoroughly (until water runs out of the bottom of the pot). This helps the core activate through capillary action.
  2. Soil is too compact or roots are blocking
     If the soil is too hard, root-bound, or very muddy, SUStee’s bottom inlet can get blocked. Try loosening the soil a little or placing SUStee in a different spot.
  3. Soil drains too quickly
     In very coarse soil, water may drain before SUStee can absorb it. When watering, try pouring a little water directly at the base of SUStee.
  4. After changing the refill
     Make sure to keep the small straw attached to the refill—it’s essential for proper function.
  5. Within 6 months of use
     Sometimes fertilizers or oils in the soil can clog SUStee. Please check our [maintenance guide] to clean it.
  6. After 6 months of use
     The refill core can naturally break down over time (thanks to soil microbes—that’s actually good for your soil!). If SUStee has been in use for 6–12 months, it’s likely time to replace the refill.

It depends on the size and the soil, but here’s a rough guide:

• S size: about 3 minutes
• M size: about 15 minutes
• L size: about 25 minutes

In some cases, especially with certain types of soil, it might take up to an hour to see the change. ⏳
So don’t worry—this timing is just an estimate and can vary depending on how much water the soil can hold.

Great question! ✨
SUStee dries at different speeds depending on whether it’s in the soil or out in the air.

• In the soil: it dries faster, since the soil environment controls the moisture.
• Out of the soil: it can take longer to turn white again.

That’s why SUStee is always designed to be read while it’s in the pot—that’s the condition it’s calibrated for.

There are two main signs:

1. The refill core has decomposed
   The core inside SUStee naturally breaks down over time. Once it’s gone, SUStee can’t function anymore and needs a new refill.
2. No color change after watering
   If SUStee doesn’t react at all, even after cleaning (see our [maintenance guide]), it means the core has reached the end of its life. This can happen after long use as soil particles and minerals build up.

👉 As a rule of thumb, we recommend replacing the refill every 6–12 months depending on your soil and growing conditions.

(We also test SUStee under tough conditions to make sure it lasts as long as possible. If you ever suspect a defect, please don’t hesitate to contact us!)

Insert SUStee so that the soil surface is between the ▼ and ▲ marks on the stick. That’s the perfect depth for an accurate reading!

下記を参考にしてください。

2, 2.5, 3号鉢 直径 6〜9cm	片手で持てる鉢	W10mm×D8mm×H120mm / 4.3g
3.5, 4, 5, 6号鉢 直径 10.5〜18cm	両手で持てる鉢	W10mm×D8mm×H180mm / 5.9g
6〜12号鉢 直径 18〜36cm	持ち上げるのに 力が必要な大きな鉢	W10mm×D8mm×H255mm / 8.0g

Not exactly! Here’s the golden rule:
👉 If the window is even a little blue → Don’t water yet.
👉 When it turns completely white → That’s the time to water.

We know it’s tempting to “just give a little more water,” but it’s best to wait until SUStee is fully white. Patience keeps your plants healthier and prevents overwatering.

• Blue = The soil is still moist. No need to water yet.
• White = The soil is dry. Time to water your plant!

Yes, it does!

• Summer: Water evaporates faster, so SUStee turns white more quickly.
• Winter: Water evaporates slowly, so the blue color stays longer.
• Spring & Autumn: Somewhere in between.

This way, SUStee helps you adjust your watering naturally through the seasons—always giving your plants just the right amount at the right time.

No worries—it won’t affect SUStee’s function. 🌿

SUStee changes color based on soil moisture, not just surface water.
So even if it turns blue when misted or rained on, it will soon return to white if the soil itself is still dry.

Not really!
As long as you don’t use them in extreme amounts, and they don’t contain a lot of oils, fertilizers (both organic and inorganic) or pesticides won’t affect SUStee’s performance.