Grusonia invicta or Corynopuntia invicta is a cactus native to the Baja California region in Mexico. This cactus is nicknamed the rat house, devil cholla and horse crippler due to its distinct appearance and features.
The cactus grows wide like a mat, under which rats usually reside. The stems of this cactus are dark green with tubercles and extremely sharp spines, with the flowers being yellow and blooming in late spring.
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How to Care for Grusonia invicta
The Grusonia invicta plants are heliophilic, which means they like sunlight, and that’s why they grow well in intensely hot regions. When they are in their growing seasons, they should be grown in places that have good ventilation and low to medium levels of humidity.
Grusonia invicta plants need a lot of sunlight for them to grow and bloom. So, you can grow them on outdoor balconies or in a garden that doesn’t get shade. But you shouldn’t leave them out when the afternoon sun is punishing.
In the afternoon, you should place them in a cool or shaded area so that the high temperature doesn’t damage them.
Grusonia invicta cacti also don’t need a lot of watering, which makes it easy to grow them. By nature, they are succulents, which is why you should water them only when the top inch of the soil is totally dry.
Overwatering can lead to stem and/or root rot, which will kill the plant. The same is true for accumulated water, and their surroundings are highly humid.
Grusonia invicta cacti need soil that is fertile and rich in gravel content. So, make sure you get a potting mix that is water-permeable and has a pH value of 6 to 7. You must find soil that has 60 percent vermiculite and 20 percent peat moss or coco coir along with 20 percent sandy soil.
You can add some organic matter for better growth. If you get lightweight culture soil, you should add vermiculite to make sure that the air in the soil is permeable. Adding some eggshell powder to increase the fertility of the soil is not a bad idea.
Grusonia invicta doesn’t need a lot of fertilizer. But if you want to add some, you should do it once every year and dilute it heavily with water. The fertilizer can be added in summer, spring and fall when the plant is in its growing phase.
The fertilizer should be slow-release, and you should add it when you are repotting the plant in fall or spring. And it should have nitrogen in the seedling phase and phosphate-potassium before and after it is ready to produce flowers.
Since Grusonia invicta prefers warm to hot temperatures, it will do well from 68 to 95 degrees F. It doesn’t do well in cold temperatures, so make sure that it is not exposed to temperatures under 50 degrees F.
Grusonia invicta plants are vulnerable to anthracnose, which is a disease that attacks these plants when the humidity or temperature is unfit for them. You will see brown spiral spots on the plant, which look like water stains when this happens.
You should cut off those parts of the plant and burn them. Also, use the specific pesticide to make sure the rest of the plant is safe.
Stem rot is also a problem for these plants and it happens due to wounds inflicted by cold weather. It’s also a possibility if they are exposed to garden soil or a garden that is not disinfected. You will see dark gray spots that look like water stains in this case as well.
Spider mites are also a threat to these plants. They are known to attack the back of the leaves and there will be structures like a spider web that will tip you off. You should wash the leaf and spray it with a pesticide right away.
You could also have an aphid infestation. In that case, the leaves will turn yellow or become distorted. These pests are likely to attack the tender parts of the plant. And you can get rid of them by flushing them with water. If the problem is large, you should get an aphid killer spray.
Grusonia invicta cacti don’t need a lot of pruning. When the flowers wither, you can just remove them. The same goes for branches, which you should do because otherwise, they can suck the nutrients that the healthy branches need.
Potting is another area where Grusonia invicta cacti don’t need much attention. In the initial run, you should get a pot that has holes for drainage. When the pot is filled, you should shift the plant to a bigger size so that the roots have space to breathe.
Propagating Grusonia invicta
Grusonia invicta plants can be propagated with seeds, division and grafts. Cut the tip of the branch with a clean knife and plant it in fresh soil. If you want to graft this plant, you should cut the tip of a rootstock and graft it with a stem of the likes of pitahaya.
Keep it together with a rope and you will see them grow together in a couple of weeks.