Plant Care  |  November 12, 2020

Cereus Cactus Care


PRO TIP: Withhold water from the plant for about four weeks in January or February to encourage new growth in the warmer seasons.

Native to South America, the Cereus Cactus (Cereus peruvianas) is a striking plant. It has a blueish-green hue, distinct spiny ribs, and can grow up to incredible, tree-like heights in the wild.

The Cereus Cactus appreciates a warm, dry environment with minimal water, and plenty of light. This desert beauty will thrive in high light conditions, so placing it in a window where it will receive direct sunlight is ideal — preferably a southern or western facing window, as they are typically the brightest. This plant will not tolerate low light conditions.

If you are unsure about lighting conditions in your home or office, we have a guide for how to measure light in your space.


Cereus Cactus Close Up

The name for this cactus is derived from Greek and Latin words meaning “wax” and “torch”.

Routine Maintenance

PRO TIP: If in doubt, let it drought! The biggest killers of these plants is root rot caused by overwatering. In New York, cacti rarely receive enough light to require watering more than once or twice a month.

Always be sure to assess your plant’s watering needs upon receiving it. Before giving your plant a drink, it is best to check the moisture level in the soil first to ensure it isn’t moist right beneath the surface. Also, consider aerating the soil of your plant before the initial watering. We compact the soil to avoid shifting during transit, so aerating can help the soil breathe and allow moisture to be released.

Cereus Cacti like to dry out completely between waterings. The most common mistake made with these plants is overwatering. Make sure that you are letting the soil thoroughly dry before giving your plant water. Cereus Cacti are susceptible to root rot, so it’s very important that you do not water the plant if you detect any moisture in the soil. During the winter months, watering frequency should decrease, sometimes to as little as once a month.

Rotate your plant periodically to ensure even growth on all sides and dust the stalks often so the plant can photosynthesize efficiently. When dusting the stalks, also take the opportunity to inspect them and keep an eye out for pests. Cereus Cacti are susceptible to scale, an indoor houseplant pest that appear in the form of small brown scabs. It is very easy to treat, however it’s best to inspect your plant regularly to ensure you catch it in the early stages.

Remember each plant is a unique living thing and may have varying needs, especially in their individual locations. Pay attention to the condition of your Cereus Cactus and its watering needs and you will have a long and happy relationship.

Frequently Asked Questions

Is it possible to under water my Cactus?

  • It is rare, but yes. Signs of under watering are typically brown edging or markings. The cactus stalks would be dry and brittle, as opposed to mushy and soft. When watering an underwatered cactus, remain conservative with the amount given because overwatering is still a possibility.

How can I tell if my Cactus is getting too much water?

  • Generally, a cactus will become less stable, droopy, and brown at the base if it is receiving too much water.

How do I know if my Cactus has scale?

  • Scale is a small, flat, round pest that attaches itself to the flesh of the plant and remains stationary. If you see small raised bumps on your cactus that are easily removed with a paper towel or q- tip, it is likely scale. Good news is it is very easy to remove the pest and treat the plant! Begin by scraping all the bumps off, and treat the plant by with a mixture of insecticidal soap, or neem oil, and water. Follow the instructions for dilution on the bottle. Dip either a soft bristled toothbrush, a q-tip, or a paper towel in the mixture apply to the treated areas. Spray the mixture lightly on the plant and soil and let it rest. Repeat in seven day intervals until you no longer see the scale. Be sure to treat the plant in the evening as the insecticidal mixture can burn the plant's flesh in direct sun.

How often should I fertilize my plant?

  • In general, houseplants will thrive when they are fertilized spring through fall. Fertilize once a month with an organic houseplant fertilizer, following the package instructions for dilution and administration. Greenery NYC uses an organic potting mix with a slow release fertilizer in the soil, so your plant will not need fertilizer within the first 6 months of receiving it.

How often does my plant need to be repotted?

  • We suggest repotting every 2 - 3 years. Cacti are slow growing, and they prefer to be somewhat pot bound so you can wait longer than you would with most houseplants. Be sure to choose a potting vessel 2”- 4” larger in diameter to allow for growth. Don’t choose a pot much larger than this as this could drown the plant's roots. If you prefer to maintain the current size of your plant, repot into the same vessel, providing new soil and trimming away some roots and foliage. Spring or summer is the ideal time for repotting as the plant is at its strongest. When repotting a cactus, be sure not to water it for at least a week after disturbing its roots, as they can enter a state of shock during the process which can make them more prone to overwatering. They return to normal after several days.

Standard Planter Instructions

There are two types of standard planters offered by Greenery Unlimited—those with drainage holes, and those without. Within these two categories are an array of sizes and styles to choose from. The presence of drainage holes and the size of the planted vessel both play a role in the quantity and frequency of water given to your plant.

Plants purchased in pots without a drainage hole have been set up with a built-in drainage system. A layer of Aeration Stones (porous, absorbent material made of recycled clay) has been placed beneath the soil to act as a reservoir for any excess water that flows through the soil. You will need to be slightly more cautious not to pour too much water into these containers as there is no way for the excess water to escape. We suggest slowly pouring small amounts of water in bit by bit, until you have reached the desired moisture level in the soil.

For plants potted with drainage, water until the excess begins to come out the bottom of the pot and into the catch tray.

Self Watering Container Instructions

The self-watering containers require a deep and thorough watering of the topsoil after they are first placed. This is important because the roots of the plants first need to grow into the reservoir in order to drink from it. Follow the standard planter instructions for at least four weeks, before testing the reservoir. During the dormant seasons, or for plants that have slower growing habits, consider top watering for up to ten weeks. 

TEST: After the initial top water period, fill the water reservoir until the red indicator reaches half way between the MAX and MIN line. If the indicator goes down over the first few days, it means the plant is ready for regular reservoir servicing. If not, be sure to continue top watering for a few more weeks, until the red indicator goes down, meaning the plant has started drinking from the reservoir. 

RESERVOIR SERVICING: Once the indicator goes down, do not refill the reservoir right away. Similar to how humans need a breath of air between gulps of water, almost all plants require a drying out period. Always allow for the reservoir to empty all the way, and after a drying out period of a few days, be sure to refill it until the indicator reaches the MAX line.

From here on out, you should NEVER topwater the plant while using the reservoir system. If you water from the top, it can drown the plant. In the Self Watering Container, the top layer of soil will eventually become extremely dry and hard, and may even pull away from the edges of the pot. This is not a cause for concern, but simply because the plant is drinking directly from its roots in the water reservoir. You may opt for adding fresh soil into the gaps between the soil and planter, so as to give the plant a nutrient boost. You may annually, or bi annually, top water the plant to flush the foot system. Only do so when the reservoir is empty and the plant is ready for more water. 

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