I’m so glad you asked for more clarity on this! When I tell people to only water their succulents when the soil is completely dry, I mean all the soil, from top to bottom.
There are two reasons for this.
First, to make sure the succulent roots have plenty of time to dry out between watering, allowing them to grow strong and healthy. You can learn more about that in episode 6 of the podcast.
The second reason is to prevent gnats from making an appearance! Gnats thrive in a wet and warm environment. If your soil stays wet too long, you’ll soon notice gnats starting to hover around your succulents. They don’t do damage but they are quite obnoxious.
But ultimately, constantly wet soil just isn’t good for your succulents, so that’s the main reason.
So how can you tell when the soil is completely dry?
There are a few ways to tell, but the method I use most often, is the weight of the pot or planter. Shortly after watering, feel how heavy your planter is (if you’re able – obviously there's going to be some pots that are too big for this method). Wait a few days and lift the planter again. It should be quite a bit lighter than after you watered it.
Wait another day or two and then feel it again. If it doesn’t seem lighter than a day or two before, you’re good to water again! The soil should be completely dry. If it does feel lighter, wait another day or two and check the weight again.
This method works really well for smaller pots, especially if you’re growing indoors.
You probably have some pots that are too big to lift. I definitely have some I can’t lift! So, other options for checking for dry soil include using a wood skewer. Put the skewer all the way into the soil, leave it for several minutes and then pull it out. If it’s cool to the touch or wet, the soil is still wet.
You can also use a moisture meter, though I haven’t found these to be reliable, especially if you’re using the Bonsai Jack girtty mix I talk about in episode 4.
Another way to determine when to water is to wait for a sign from your succulents. Your succulents will give you clues as to when they need more water. For example, an early sign your succulent needs water is it will start to have a dull color and won’t look as vibrant or glossy.
I’ve put together a free guide to help you determine when your succulents need water. The guide will show you how to determine if your succulent needs more or less water.