You bought your cactus excited because you wanted to see it grow, but you bought it only to see it do nothing week after week.
Why is my cactus not growing? Check the season because cactuses stop growing in the summer to focus on surviving high temperatures. Other factors that can stop your cactus from growing include a lack of fertilizer, too big of a pot, soil mixture and lack of cool temperatures.
If you’d like to learn more about why your cactus might not be growing, keep reading because we will explain further.
Naturally Slow Growing Plant
You have cases where your cactus could be growing, but you don’t see it because the plant grows slowly. Depending on the species, most cactus grow to the size of a marble in the first six to 12 months.
After two to three years, they will reach a few centimeters in height. Some species like the Pereskiopsis can grow up to 1 inch per week, but this shows you the exception. Most cactus will only grow 1 to 3 centimeters per year once reaching maturity.
Cactus grow slowly because of the need to survive. They must conserve energy to put it into survival in the barren deserts, rather than pour the energy into fast growth.
Provided this isn’t the reason, let’s have a look at why your cactus may not be growing.
Summer Season: No Growth
In their natural environment in the desert, cactus stop growing altogether as they focus on survival. The lack of water during the hottest months demand a different focus. Water evaporates from the plant, a process known as transpiration, during this time.
We talked about the summer season, but cactus go dormant in the winter season as well. Most plant experts advise you not to water your cactus too much during this time because it can have elongated growth and thinning. Ultimately, you end up with a weaker cactus.
However, don’t stop watering your cactus altogether because it still needs water. You might water your cactus once every month or every five to six weeks in its dormant stage. Keep in mind, your cactus won’t grow as much during this dormant period. Also, don’t fertilize your cactus in the winter months because it doesn’t actively grow during this time.
Lack of Fertilizer
Even cactus plants require nutrients in the soil like phosphorous and some level of nitrogen. To learn what happens when cacti don’t receive enough phosphorous, read my article, “Why is My Cactus Turning Purple?”
Previously, we said that you shouldn’t fertilize your cactus in the winter season because of its dormancy, and it won’t spark new growth.
When do you fertilize your cactus to encourage growth? You could put fertilizer in the soil of your cactus two to three times per year. Do it in the spring, summer and fall of the year.
Technically, you only have to do it once a year, and the spring season works best because it is the growing season, but doing it more will actively encourage growth throughout the year. The late spring to early summer experience the peak of the cactus growing season, which makes it the ideal time to feed it fertilizer.
Many cactus lovers will use a time-release mechanism to feed their cactus throughout the year to ensure that it doesn’t miss out on the peak growing times.
Exercise caution not to overfeed your cactus either because this can weaken the plant, rather than to help it to grow. Signs that you have over fertilized your cactus include:
- Wilting and yellowing on the lower plant
- Rotting roots
- Slow to non-existent growth
- Crust of fertilizer on the soil
Be careful not to over fertlize your cactus either because this can also stop it from growing. How a cactus grows will depend on its species, but fertilizer can make a big difference.
Schultz Cactus Plus 2-7-7 Liquid Plant Food can help your cactus to take off. If it doesn’t seem like it’s growing, specialized fertilizer like this may help. You want to use a liquid fertilizer low in nitrogen for cactus fertilizer. Fertilizers with too high of a nitrogen content can cause root rot. In some cases, you may only have a few rotting roots, in which case, you can just prune the roots.
Using Too Big of a Pot
One of the reasons that your cactus may not be growing could come from the fact that you used too big of a pot. Instead of growing upward in these cases, the cactus roots will experience more growth.
In fact, too big of a pot can even kill your cactus. Larger pots hold in the water longer, and it fills more space with moisture. This can cause root rot and slow decay of your cactus. Your cactus may not be growing because it’s trying to survive. You only want to use one size up from the last sized pot that you had.
The right-sized pot ensures that your cactus grows properly. Most cacti like small spaces because they find it cozy, and they can remain in the same container for a couple of years. Don’t use too small of a container either, however, because that can prove equally as detrimental.
You want to repot your cactus every two to three years to ensure optimal growth. Use of the right container size will encourage your cactus to grow correctly. If it isn’t growing, this could be one of the reasons.
In some cases, cacti don’t grow because of the wrong soil mixture. You have to use soil with good drainage because cactus plants need this to keep from root rot. In their natural environment, this is the type of soil that they’re used to.
Specialist cactus soil will especially work well because they have specifically designed it for that purpose. Organic Potting Soil, Cactus and Succulent Soil Mix may be able to help. You can also use this to repot your cactus. Choosing specialist soil like this ensures that you have the right mixture on hand.
Otherwise, you can make your own cactus soil using 3 cups of sand with 3 cups of regular soil and 2 cups of pummice or perilite.
In particular, cactus might grow slowly from the wrong soil because of the water damage that occurs. Let’s say that you poured water over your cactus, but you used the wrong soil, and it holds in the water longer. Because of this, it damages the plant roots, which can stop your cactus from growing altogether, or it will grow more slowly as it tries to heal and survive.
Lack of Cool Temperatures
Cacti like temperatures between 45 degrees Fahrenheit to 85 degrees. However, anything under 55 degrees and they go dormant thinking it’s winter season. After that point, they start to enter survival mode, and this explains why they won’t grow.
Interesting to note: Some cactus species can survive temperatures as low as -20 degrees Fahrenheit. The cold moisture is what increases the likelihood of them dying. At night in the desert, temperatures can drop to as low as 26 degrees Fahrenheit because nothing in the desert holds the heat in.
Maybe you have your cactus in an area where it gets too much heat. This could explain why your cactus won’t grow. In fact, you can tell when your cactus receives too much sunlight. If you’d like to learn more about that, I wrote an article on “Why is my Cactus Turning White?”
Sunlight: Essential to Cactus Growth
Most cactus species will require four to six hours of sunlight to grow properly. Some cactus species love direct sunlight, while others would prefer being in less direct sunlight. When a cactus doesn’t receive enough sunlight, you will see elongated growth.
It can also produce etoliation, which results in poor cactus growth. Instead of proper growth, the cactus will grow overly tall and weak, reaching for the sunlight.
Important to Note: You have to exercise caution with putting your cactus directly in sunlight because this can cause sunburn if your cactus isn’t used to it. In some cases, your cactus doesn’t want the direct sunlight.
How to Speed Up Cactus Growth
Now, we have talked about cactus plants and what can stop them from growing. We have gone into depth on why they might not grow. Now, we will look at how to speed up the growth of your cactus. In addition, we will cover what not to do to speed up its growth.
If you don’t like the speed of growth with your cactus, in some cases, you may want to buy a faster-growing cactus. Some of the faster-growing cactus species include:
- Trichocereus bridgesii
- Ficus indica
- Notocactus Magnificus “Balloon Cactus”
To speed up the growth, maintain a consistent watering schedule. Most cacti need water once a week. A good soaking is best. In the dormancy period, don’t try to get growth out of the cactus because it can slow down its growth or cause elongated growth that weakens the plant.
You also want to allow for the right kind of air circulation. Cactus need good air if they will grow. Stagnant air or air high in humidity can kill the cactus if continues over a long period of time. In fact, having a fan turned on can keep the air flowing in the room.
Don’t place a cactus under an air conditioner because the cool air can rob the plant of much-needed moisture from the air taken in by its spines. It can also freeze the plant cells. In addition, don’t place the cactus near a radiator in the winter season.
Your cactus may not grow for multiple reasons, but in some cases, it could simply be due to it being a slow-growing plant. Many cacti species don’t grow quickly. Check your species to learn how fast it grows. If you wanted a faster-growing cactus, choose from one of the species that we highlighted above. When that isn’t the problem, look at the possible causes.
If you’d like a good collection to get started, try the Instant Cactus/Succulent Collection. You receive eight plants, which becomes the perfect addition to your garden.
When you have a single cactus that doesn’t appear to be growing, you can also buy other cactuses as a way to add to your collection while keeping it fun. Owning plants can be a rewarding hobby.