Whether desert cactus or rainforest succulent: cacti are hungry artists and can store large amounts of water in their stems or tubers. Today we answer one of the questions we hear the most: How often do you have to water a cactus?
Many people buy cacti because they are extremely easy to care for and do not depend on a continuous water supply. Nevertheless, when watering cacti, care mistakes often occur that lead to the death of the plants. Most gardeners know that cacti need little water, but they don't realize how little.
Cacti belong to the group of succulents , so they are particularly good at retaining water and can do without fluid for a long period of time. But not all cacti come from the same environment. In addition to the classic desert cacti, there are also species that grow in dry mountain regions or even in the rainforest. Thus the origin of the respective cactus species provides information about its water requirements.
How often should cacti be watered?
Although it is common knowledge that cacti are rarely watered, it is interesting to note that most of the specimens do not die because of insufficient supply, but are downright drowned. In their Mexican homeland, the succulents are used to rare but heavy downpours. You should imitate this form of water supply at home if you want to water your cacti properly.
So water your cactus very rarely (about once a month), but then water it thoroughly. For this, it is important that the planter in which the cactus is located ensures good water drainage so that no waterlogging occurs, because permanently wet feet are the death of every cactus.
Water your cactus once enough that the potting soil is completely saturated and then pour away any excess water. Then the cactus is dried again and left alone until the substrate is completely dry again. Only then (preferably three to five days later – exercise your patience!) can you use the watering can again.
How to water cactus properly
Those who water their cactus frequently but little can have difficulties in correctly assessing the moisture of the soil and the water requirements of the cactus. Therefore, it is better to soak cacti similar to orchids instead of watering them, if the plant pot allows it.
For the soaking method, place the cactus together with the plant pot in a tall bowl or bucket with room temperature water and leave it in it until the substrate is completely soaked. Then take the cactus out again, let it drain well and put it back in the planter. The cactus lives on the water it has soaked up for the next few weeks and no further care is necessary. Before soaking again, the substrate should be completely dry.
The right substrate helps with watering
As already mentioned, there are many different representatives of the approximately 1,800 cactus species with different origins and correspondingly different needs. Cacti from the temperate climate zone need more water and nutrients than, for example, a cactus from the dry desert. In order to meet these requirements, it is advisable to pay attention to the right substrate when buying and planting a cactus.
While water- and nutrient-hungry cacti usually stand in humus potting soil with a rather low mineral content, desert cacti should be placed in a mixture of sand and lava. The individual substrate components have different permeability and water storage power, which are adapted to the needs of the plants. The right substrate helps prevent the cactus from getting wet feet.
The right irrigation water for cacti
Cacti are not only modest in terms of the amount of water, they also have no special requirements for irrigation water. Normal tap water with a pH between 5.5 and 7 can be used to water cacti without any problems. Even if cacti are rarely sensitive to lime, it is good to let the water stand in the watering can so that the lime settles in very hard water and the water can reach room temperature. If you have the opportunity, you can pamper your cacti with rainwater or decalcified tap water.
How often should you water cacti in winter?
In winter, indoor cacti also take a break from growing. The room temperatures in the interior remain constant, but the light output is much lower in the winter, to which the plants respond by stopping growth. You should therefore water your cactus even less between September and March than during the summer months. The succulent plant's water consumption is now at a minimum.
Desert cacti do not need any water at all in winter. A little more has to be poured if the cactus is directly in front of or above a heater, because the warm air from the heater dries the plant out. At the beginning of the new growing season in spring, the cactus is showered over once to stimulate growth. Then you slowly increase the amount of watering water as the plant needs.
How long can a cactus go without water?
The only thing that really kills a sturdy cactus in the right place is waterlogging. If the roots are permanently in a moist environment, they rot and can no longer absorb nutrients or water – the cactus dies. Therefore, make sure that excess water can drain off well after watering the cactus and regularly check the moisture of the substrate on new cacti in order to assess their water requirements.
Most cacti do not need to be watered for a long time (six weeks to several months) after a strong watering. The larger the cactus, the longer it will tolerate drought. A vacation replacement to water your cacti is therefore not necessary.
Can you overwater a cactus?
The simple answer? Yes.
In fact, too much water is the number one cause of cacti. See what your cactus needs, but remember to keep about this: once a month water in winter, once every two weeks in spring and once a week water in the summer when the weather is really hot. I'd rather water too little than too much.
One sign that a cactus really doesn't get enough water is that it shrinks. Then you'd better water a little more. Very important: make sure that the earth is never moist. Therefore, water through the bottom of the pot. For that, you need a saucer that you put under the flower pot. After a while, see if there's any water left on the saucer. Throw that away or give it to another thirsty plant.