Watering the Blue cereus will help transport the nutrients that it needs from the soil to the rest of the plant. Without enough moisture, the Blue cereus won't remain healthy or might even become malnourished. Watering should be done when you see some signs that the plant is thirsty. When you're in doubt, you should never overwater as this can be a way to kill them.
The best way to water them is the soak and dry method. When you see that the soil becomes too dry, you should soak them in water until you see that the pot is dripping with water underneath. Then, go for weeks without watering to give the soil a chance to rest.

Water this succulent efficiently and make sure to cover the entire pot. Set a saucer at the bottom of the pot so the roots will get enough moisture. When you see that the soil begins to saturate, take out the saucer immediately. The holes in the pot and the amount of soil will determine the frequency and the quantity of water you should give your plant. A can of water is often more than enough for the Blue cereus especially if they are planted in pots.
When you plant them in the garden or outdoors, you need to include the rainwater they receive. About an inch of rainwater is more than enough to last them for a few weeks, so refrain from watering. When they are outside, you need to water them in the morning with about a gallon of water after you see that the soil is bone dry so the sunlight can help evaporate the excess moisture.

Most of the time, you only need to water your succulents once every two to three weeks in the summer and spring. During the winter and fall, reduce the watering or avoid this as this plant tends to become dormant.
Let the soil dry completely, and it's always a good idea to lean on the side of underwatering rather than overwatering. When they are in the pot, water deeply at intervals to encourage healthier soil growth.
When they are planted outdoors, never water them lightly as this will result in more shallow root growth. Wait for a few weeks and only give them a drink when the soil around them is too dry.

Another tip when watering this species is to water it from the bottom. This is for the proper absorption of water to the roots, enabling it to circulate the nutrients from the soil towards its whole body. When you accidentally spill water at the top part, this can cause the development of diseases and fungi.
Use sprinklers when you have irrigation systems. Get the small sprinklers if you have Blue cereused in your garden. It's best to get the revolving ones that allow you to change the water delivery patterns whenever you need them. Avoid turning on the sprinkler on windy days. Make sure to use the soak and dry method regardless if the Blue cereus is in a pot or your garden. This will evenly distribute the moisture across the root systems resulting in healthier growth.
Some owners might want to get a built-in drainage system for their succulents. This is where layers of porous materials like recycled glass or hydro stones are placed beneath the soil. They will generally be a reservoir for excess water, so it's important not to pour too much water into these built-in systems.

Before you give this plant a drink, it's always a good idea to check the soil's moisture levels by poking your finger in it or using a moisture meter. This will tell you whether the soil is already too dry or if there's still moisture. It's a technique used by owners of smaller potted plants to know whether it's time to water or not.
Assess the needs of your Blue cereus and know that it requires watering every two weeks during the summer. You can go as far as three weeks in the hot season before watering this, but in the fall or winter, there should not be any water at all. Allow the soil to dry between irrigations.
They can be grown in greenhouses and other warm spots indoors and thrive well. When your plant is getting too much light, you can increase the watering frequency as long as you see that the soil is dry. They can also be grown outdoors, where you will need to water them less.
Give it enough water once every three weeks; this should be more than enough. Don't rely alone on irrigations and sprinklers to reach their bases. Use a soaker hose that will hit the ground and spread the water. Make sure it won't hit much of the body of the plant as this can result in diseases.

When you see that the Blue cereus begins to turn yellow, know that this can be caused by underwatering or overwatering. When the soil is too wet, then there might be the presence of fungal infections. You should allow everything to dry, and you should not overwater.
Also, the browning and dropping symptoms indicate that your plant is getting too much moisture and water. If there's not enough water, the indication can be seen with the yellow tips that can begin to form on stems and branches.
When you're still in the process of buying the Blue cereus, make sure to ask first if the soil is properly draining or sandy. When the topsoil does not properly drain, there's a chance that the plant will likely not receive enough water in the future.
Another thing is that the Blue cereus tends to die when it's constantly getting overwatered and if it's receiving too much rain if planted outside. Use rainwater or distilled water whenever possible as the plants don't like many minerals in their drink.
You can see the squishy stems, drooping growth, and discolored parts that are all signs of too much moisture. It's critical to give the species time to recover and allow the pot to dry. Transfer it to a different container to avoid root rot and prevent it from dripping. If planted outside, you can also transfer it into a pot, especially in the winter, to help it recover.

Blue cereus is very tolerant of drought. This means that you don't need to water them very often. Watering frequency should also depend on the climate where you live. In a dry environment, you can make the watering conditions adapt well to your plants' needs. When they are in their early flowering stages, you might want to increase watering to help them grow. When they are receiving enough sunlight, water only in the morning.
Specifically, they can be watered once every 10 to 14 days during the summer. You can increase this frequency during times of heat waves and make sure to mist the base from time to time lightly. When it's too cold, you can cut back on watering or once every 21 to 28 days when it begins to cool down.

When you've just repotted the plant, you should wait for a week before you can water your Blue cereus. When it's time to water them, be generous until you see the water coming out of the potholes but don't make it a deluge. When they have already grown and received medium light, you might want to water them once every 2 to 3 weeks since they are very tolerant to drought.
In the winter, you will further need to cut back on watering. The ideal time is to water it once every 3 to 4 weeks as long as the soil does not feel too dry. Winter is their resting season, so they don't consume a lot of energy or grow at this time.
If you grow the plants outdoors, rainwater can be another excellent alternative when you want to hold back on watering. When you live in an area where you don't get much rain, water at least once every three weeks to prevent the soil from drying too much.
In humid locations, there's no need to water a lot. When keeping the Blue cereus indoors, you won't have to keep the moisture high, especially if the plant does not receive too much sunlight. When there's too much moisture and not enough light, this can spell disaster for the succulents.

The Blue cereus growing outdoors can thrive with rainfall, but when it’s planted in a pot, you need to be careful while Blue cereus is still in the growing stage. One way to prevent overwatering is to check the top bottom inches of the soil for moisture. Once again, you need it to be dry so you can water it again. If you're unsure of the amount and the frequency, especially during the growing phase, go with underwatering and slightly increase it when you see a need. It's always a good idea to take a picture of the Blue cereus and note how it looks after watering it.
You can take things further by using moisture meters or hygrometers to check the air and soil moisture. These tools are available from various shops and can be valuable when you want to know the readings for humidity and water.

Know that these plants can survive for weeks without any water. This is because they have water storage capacity that can conserve water for a long time. so it will conserve enough water to stay alive even if they are in the wild.
When they are fully grown, water them less since they can survive without water compared to when they were small. You need to give them time to get used to your climate and growing conditions before watering them. If they are indoors, keep them in indirect light and water them less frequently. Avoid using cold water during the winter and months, and you might be overwatering when the plants are located indoors. Give this a rest, especially during the winter and fall.
When they are outdoors, refrain from watering too much. They should be able to get enough humidity, moisture, and rainfall that will keep them alive. Only water when you see that their leaves are becoming droopy and yellowish. Always lean on the side of underwatering as the Blue cereus is very tolerant to dry conditions. They don't like wet feet and might wilt when you water them too much.

Blue cereus and other summer dormant plants require some care in the spring.

Tip 1: Water the plant whenever the top layer of soil begins drying out to help support its vigorous spring growth. Do not allow the soil to completely dry out and avoid getting moisture on the plant’s crown (center).

Tip 2: Apply a balanced fertilizer every two weeks until summer to encourage blooming.

Tip 3: Move container plants into the sunlight, ensuring the plant receives several hours of light a day.

Tip 4: Prune back any dead growth but do not remove green stems.

Since Blue cereus and other cool weather plants are dormant in the summer, they do not require a lot of care.

Tip 1: Allow the soil the top layer of soil to dry out before watering and do not continue fertilizing.

Tip 2: Removing any spent flowers and dead leaves can encourage reblooming in the fall.

Tip 3: Move a container plant into a shady area during its summer dormancy period.

Your Blue cereus will wake up during the cool fall.

Tip 1: Give your plant a good cleaning as it wakes up, pruning away dead or diseased branches and yellowing leaves, or even weak branches, in order to encourage fresh and strong growth and keep the plant looking its best.

Tip 2: This is the time to repot your plant if you choose to move its location.

Tip 3: Begin regular watering once again to keep the soil slightly moist, but not soggy.

Tip 4: Continue your regular fertilization schedule during the fall, and make sure it's receiving adequate amounts of light to support its growth.

Your cool-loving Blue cereus will be at its most active during the winter.

Tip 1: Watering is essential. Make sure the soil is moist during this active growth, keeping up with a regular watering routine.

Tip 2: Your plant should receive adequate sun, but plenty of shade is also important, so make sure the plant is in a location that’s shady in the afternoon.

Tip 3: Continue your regular fertilization schedule, feeding it once or twice during this season or using a slow-release variety.

Tip 4: You may also choose to propagate or repot the plant during this time, when it’s actively growing.