Generally speaking, cacti grow very slow but now I seem to have a few cacti that stopped growing at all. I wondered why and did some research, this is what I found.
There are quicker growers among the many but most small roundish cacti you will find in your local store will never really become big. Some will never grow larger than your fist. Originally wild cacti will grow much better! But there are a few things you can improve to make your cacti grow again. Let's look at what you can do about it.
How to check if my cactus actually grows
If you choose to start growing cacti you plan to be stuck with them for the coming years or even decades, you have to be rather patient while growing them.
But how do you know if your cactus actually grows?
To check, look at the center from above. If new differently-colored spines called areoles appear, it's growing.
You might want to take a few pictures to keep track of the growth because your cactus may only make a few of these differently-colored spines (areoles) each year!
Why did my cactus stop growing
Cactus may have a reputation of being easy to grow, which many of us have proven completely wrong. Your cactus is a specialized houseplant that needs certain conditions to be able to grow and bloom. These conditions are not difficult to create at all but are often overlooked.
You have to make sure your cactus gets enough direct sunlight, gets the proper amount of water and gets fresh nutrients from time to time.
Within this blog post, we will go over a simple guideline you can stick to and make sure your cactus stays growing happily for years to come.
Wrong soil mixtures
The soil your cactus is planted in will also affect its growth performance. There are probably hundreds of what will be claimed "best" soil mixtures.
In reality, I aim to have a mixture of about 1/3 washed sand, 1/3 soil and 1/3 gritty amendment such as pumice (volcanic rock).
If your soil mixture contains to much sand it will compact your soil and make a very heavy mix. This will result in the roots of your cactus being unable to grow deeper into the planter pot, and therefore not grow.
If otherwise, your soil mixture contains to much soil with not enough gritty amendment (adding drainage) your soil mixture would stay to wet.
This would rather result in the roots of your cactus rotting than your cactus stopping from growing.
If you have had your cactus for over a year another common cause would be that your cactus has completely absorbed all the nutrients that used to be in the soil.
The soil has almost certainly compacted down so its harder for the roots to do their job. You can start by putting fertilizer in the water, but you will be amazed by what repotting your cactus with some fresh soil can achieve.
Yes, the size of your planter does matter, if your planter pot is too big, your cactus might only be growing roots instead of growing the cactus itself.
It will fill your planter with roots first before growing your cacti. If otherwise, your planter pot is to small your cactus will be unable to grow sufficient roots to sustain your cactus. This will make your cactus stop growing.
What can I do to make my cactus grow again
Just like with any other garden or houseplant, fertilizing your cactus plants will help them adapt, actively grow, grow their flowers and even multiply if that’s one of their characteristics.
Cacti fertilizer requirements are very easy. Any good houseplant food (diluted to half) that’s higher in phosphorus than nitrogen is a good choice.
At a minimum, you should fertilize your cactus plants once a year. But if you’re really organized and can set up a schedule, feeding them 2-3 times per year in the spring, summer and fall will easily satisfy your cacti fertilizer requirements.
Most cacti will grow during the warm summer months and not grow at all during the winter months. During the summer months, you should put them out on the patio or in front of a sunny window.
The best way to ensure growth is to place them outside into full to at least partial sun with protection from heavy rain.
But remember that the more sun they get, the more water they’ll need. You can leave your cacti outside from about Easter till the end of November, just before the first killing freeze of the year.
Repot your cactus
If your cactus has been sitting in its planter for quite some time now, a good chance the soil has run out of nutrients. If you tried adding some fertilizer already but didn't see any results you should repot your cactus.
If your cactus had grown over time maybe it's a good idea to take a planter pot a size bigger to give the roots the room they need.
While repotting your cactus make sure your cactus is planted using the correct soil. Hard to go wrong with commercial cactus soil but I find that the drainage provided by the soil often isn't enough.
I like to use a mixture of about 1/3 washed sand, 1/3 soil and 1/3 gritty amendment such as pumice (volcanic rock).