Succulents change colours.
Well, majority of them. In fact I only grow succulents that will change colours because they are more fun and challenging too.
I won't recommend beginner to try to stress them; whilst it's more fun to do so, stressing them is all about water, sun control and temperature difference.
Criteria for succulents ready to be stressed
1. Healthy succulents.
I could not emphasize how important it is. If you have recently repotted your succulent (eventhough she's healthy) your succulent will need some time to recover and acclimate. I would say allow for a week or two. Healthy succulents also mean they have established strong roots to absorb minimal water and survive under maximum sunlight. Read here if you are newbie and want to nurture them to be ready for this step
2. Stay outdoor
Yes, your succulents must have been living outdoor. If you want to stress your indoor succulents, slowly introduce them to morning sun or shaded area and don't forget about air circulation. Read here about growing succulent outdoor. Stressing your indoor succulents would not have maximum stressed colour, in fact they are called 'blushing' instead of 'stress'
Ok let's talk about how to stress them:
Sunlight or UV
When placed in the sun or extreme temperatures, the anthocyanins are in higher concentration in the plant cells. The anthocyanins act as antioxidants protects plants against overexposure to UV lights and extreme temperatures. It’s also known that anthocyanins which are more stable in lower temperature. That’s why we often see succulents green in summer and color up during spring, fall and winter.
Succulents are actually very picky plants, not enough sunlight will cause them leggy and have wide spread leaves as they yearns for more sunlight for photosynthesis. Too much of sunlight will cause sun damage. So probably ask yourself WTH am I doing this? Well, so that they look pretty and I can IG them!!?
Under adequate sun exposure (ideally not more 25 degrees personally find it harder to control beyond that) they will produce more anthocyanins to protect themselves against overexposure to UV lights.
After years of growing them outdoor, I would say UV value ratings are actually more important. My ideal uv reading would be not more than 3 if it's beyond that it means it's too sunny for them and you probably need to put a layer of sun shading net to protect them from sun damage. Again I'm not too fussed about sun damaged on my babies.
p/s: you still get some UV even when it's cloudy (except winter, UV value is 0)
Succulents love being dry with high circulation which is why they are grown in high porosity growing media. Summer humidity is one of the most common way to cause rotten stem or roots so please do not keep them in closed greenhouse.
This is the key for perfect stressed succulents. Overwatering will cause them losing the rosette and the leaves will be wide open. Try reduce the water frequency. I only water them when third bottom layer of the rosette leaves starts to be little soft. I water around them until the water is dripping from the pots and leave them overnight to dry. Remember the pots and soil must be dry prior to full sun exposure next day.
Whilst water and sunlight play important roles. I find the easiest way to them to change colours are the extreme temperature difference. Except summer, your babies should be showing off their stressed colour due to the mild UK temperature. Summer is the best time for them to grow as many babies as possible and summer is too warm in fact they will basically lose most of colours except some succulents will go into summer hibernation ie greenovia.
There are many potting mixes for succulent but the key is to get potting mix that has high porosity.
The Transformation of Echeveria Raindrops.
Raindrops by Dick Wright (US) is famous for her red bumps and is quite a demanding plant. She needs full sun to maintain her bumps and massive temperature difference to keep her stress colours. So she is a perfect plant showcase her potency.
I bought her back in April and this was how she looked like originally.
April 2018- as you can see from the photo, despite she had her bumps but she's all jade green; this means she got full sun but water frequently.
May 2018- Didn't take long to stress her as the weather was still mild as we had full sun during day time and cooler at night.
June 2018- she grew at ridiculously fast and blooming!
July 2018- the 'Heat wave' month. She lost her blush as the she's protected under the sun shade net and I watered her more frequently. To be honest I just wanted her to survive the heatwave.
September 18- Finally summer came to an end and here comes the stress colours. I have repotted her into smaller pot so that I could control her size. She still lost her blushes but the bumps remain (that's due to fun sun)
October 18- this month had been very nice and warm. We had sunny day and cool night and her blushes are back!
November 18- the transformation has completed! Her stressed colours are back.
As you can see stressing a succulent is way more fun and very challenging at the same time as you are constantly checking the forecast and research for better soil/ pot/ water frequency/ water ph...
I'm actually not too fuss about full sun but I definitely love spring and autumn sun with some chilly wind. After years of growing them outdoors, I can conclude that UV value is actually more important. Full sun might increase the risk of getting sunburned. Spring and Autumn are usually the best seasons to stress them due to full sun during daytime and low temperature at night. You still get UV when it's cloudy. As long as the UV value is over 1 they will still blush.
So the key of stresssed succulents:
- grow outdoor (nothing is better and cheaper than these)
- ideal UV
- water less
- high air circulation (means less humidity)
- good growing media
- spring, early summer, autumn, early winter