Updated: Apr 26, 2021
Stress, when it comes to succulents, means putting them in situations that will bring about more compact growth/shape and stronger colours.
Just like for humans, stress for succulents can be both a good and bad thing, depending on how stressful things get and how long it lasts! In general, stress isn't all that bad for succulents. It's something they go through in their natural environments on a seasonal basis and it's often what triggers growth, offsetting (producing new plants), and flowering.
We love our succulents and sometimes can baby them a bit too much (ie, water too much!) or not give them the right environment, resulting in stretched out growth and loss of colour. There's a number of types of stress you can put your succulents under to ensure they stay as beautiful as the day you got them.
We all know succulents love the sun. They're desert plants after all, so most are used to getting lots of direct sun during the day. I've found that at least 6 hours a day of direct sun is needed to ensure succulents keep their strong colour and compact shape. So, what exactly is direct sun? For most definitions, that means the plant is outside. Direct sun when indoors is always going to be more weak than outside as it needs to filter through windows and cannot come in from above.
I grow all my plants in a greenhouse in my backyard which gets sun exposure from 6am to 8pm in the summer. This is ideal for sun-loving Echeveria who always get the top shelves in my greenhouse. Other succulents can't handle this strength and amount of sun and need to sit on a lower shelf in a more shaded spot. These include haworthia and some kalanchoe. It's best to do some research on your plants to ensure you're giving them the right amount of light.
The right amount of sun will encourage compact growth - that means there will be very little or no space between each leaf. If you can see stem between your leaves it's a good sign your succulent isn't getting enough sun. The right amount of light will also ensure your succulent's leaves grow upright and aren't unnaturally long. Another way to tell if your succulent isn't getting enough light is if the leaves hang downward and are longer than usual - that means they're flattening out and stretching for light.
"But I live in Canada", I hear you say, "there's way less light here than more southern countries". True, which is why it's more important to keep your succulents outside where even if it's cloudy they get a lot more light than indoors. You can also consider getting a grow light to help your succulents along if you need to keep them inside or if the winters prove to be just too cold and dark. I use a grow light for my propagations over the winter to ensure they don't stretch out when they're just starting out. But sunlight is only one factor in stressing your succulents to perfection. Read on to see how to stress by withholding water.
In the wild, succulents can go weeks, even months without water. The desert climate most succulents come from is dry most of the time and experiences bursts of occasional rain which soaks the ground. It's best to try and mimic this environment when watering succulents by watering occasionally, but deeply. There's some bad advice floating around out there that succulents like to be misted often and this is absolutely opposite to what you should do! A well-draining potting substrate and drainage holes in your containers are also a must.
In the winter some of my succulents can go for a couple months without being watered. I know they can handle this from experience but as a rough guide succulents with chubby leaves can use the water stored in them as reserve when they're not getting watered. This is why the bottom leaves of succulents can dry up and die. This also avoids the stretched-out look that succulents get when they're watered while they're not getting enough light.
In the summer I tend to water my plants every 2-3 weeks or so, even though they get tons of light. This means they're usually under both light and sun stress. If you're new to succulents it can be difficult to adjust to depriving your plants of water but they'll look better for it!
The one final stressor you can use to ensure your plants stay looking beautiful is root stress. Quite simply, this means putting your succulents in a pot or planter that is small to constrain the roots. When the plant's roots can't stretch out this causes stress. As a guide try potting your plants in a container that's slightly smaller than the width of the rosette.
Succulents actually like root competition - this can be done by putting them in the same pot with other succulents so their roots have to fight for space. You'll see this stress technique used by many Asian growers, where the small pot/bonsai style is popular. This is the easiest way to add stress to your succulents and quite useful if you're short on space!
Transforming dull green succulents into colourful compact beauties can be very rewarding (especially if you take before and after pictures) so give the techniques above a try and let me know how it goes!