If you've ever wondered "Is my plant ready for water?", you're not alone.

Overwatering is one of the most common reasons houseplants struggle. Sustee takes the guesswork out by letting your plant tell you exactly when it's thirsty. 

Ready to get started? Shop the full Sustee range and find the right size for your plants.

What is Sustee?

Sustee is a reusable soil moisture indicator that shows you when it's time to water your plant.

Simply insert Sustee into the pot and let it do the monitoring for you.

Instead of following a watering schedule, you'll know when your plant actually needs water.

How to use Sustee

Step 1: Insert Sustee

Insert Sustee into the soil close to your plant, ensuring the sensing tip reaches the root zone. For the most accurate reading, place it within approximately 20 cm of the plant rather than right against the edge of the pot.

Step 2: Water Thoroughly

After inserting Sustee for the first time, water generously until water drains from the bottom of the pot.

The indicator window will gradually turn blue, showing that the soil has enough moisture. Depending on your potting mix and the size of your Sustee, this can take anywhere from a few minutes to around an hour.

Step 3: Check the Colour

Sustee uses two simple colours:

💙 Blue = Your plant has enough water

🤍 White = Time to water

Wait until the indicator is completely white before watering again. Even if you still see a little blue, your plant doesn't usually need more water yet. Not sure which size you need? Check out our Sustee Size Guide.

Why does Sustee work so well?

Every plant is different.

Some need watering every few days, while others can happily go weeks without it. Temperature, light, humidity and the season all affect how quickly soil dries out.

Instead of guessing or sticking to a calendar, Sustee measures the moisture around your plant's roots—the area that matters most. This helps reduce both overwatering and underwatering.

When should I replace the refill?

Sustee is designed to be reused.

Over time, the natural refill inside the indicator gradually wears down and should be replaced.

Typical replacement times are:

• Potting mix: 6–9 months

• Inorganic mixes: 9–12 months

• Bark or sphagnum moss: 1–2 years

• Hydroponics: 1–2 years

If your Sustee no longer changes colour correctly, even after cleaning, it's probably time for a fresh refill. When it's time for a replacement, you can browse our Sustee Refill Collection.

Frequently Asked Questions

Can I use Sustee with any plant?

Yes! Sustee works with most indoor plants, outdoor container plants, herbs, vegetables and many specialty potting mixes.

Does the season matter?

Yes. Your Sustee will usually stay blue for longer during winter because the soil dries more slowly. In summer, it may turn white much sooner as plants use more water.

Can I wait a day or two after Sustee turns white?

Absolutely. White is your indicator that watering time has arrived, but you can still choose exactly when to water if it suits your schedule.

My Sustee didn't turn blue after watering.

When using Sustee for the first time, make sure you water thoroughly. If it has been in the same pot for a long time, try moving it slightly or gently loosening the soil around it so moisture can reach the sensing tip more easily.

How do I clean my Sustee?

If soil builds up over time, soak the lower end of Sustee upside down in warm water with a small amount of mild detergent for about an hour. Allow it to dry until the indicator turns white before using it again.

Let Sustee do the guessing for you

Healthy plants start with healthy watering habits.

Whether you're caring for your very first houseplant or a home full of greenery, Sustee makes watering simple, accurate and stress-free.

Ready to water with confidence?

Whether you're buying your first Sustee or replacing an old refill, we've got everything you need.

Shop Sustee →

Shop Sustee Refills →