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Cactuses (Cactaceae) are very popular ornamental plants. We give expert tips on what to consider when caring for and fertilizing the prickly plants.
Cacti (Cactacea) are a family within the order Caryophyllales (Caryophyllales) and belong to the flowering plants (Magnoliopsida). In general, the cacti family includes more than 100 genera and over 1500 species. These numbers alone give an idea that cacti are much more diverse in terms of their morphology and physiology than you might think at first. There are tree-like species such as Pereskia grandifolia, but also very tiny species such as Blossfeldia liliputana. What they have in common, however, is that they are all based on the American continent. Here their occurrence extends from southern Canada to Argentina and Chile. They inhabit various habitats from tropical rainforests to dry deserts. What these very different habitats have in common: Seasonal water availability.
Cacti are succulents. They can store moisture in their tissues and survive even in severe drought. The thorns also minimize water evaporation and also protect against predators. Just as they can endure exhausting heat, hardy cacti also survive temperatures down to an almost unbelievable -20°C. The hardy species include Chamaecereus silvestrii and Cylindropuntia imbricata. Not least because of these properties, cacti are considered the Spartans among ornamental plants. Put it in the sun, some water and nothing more can happen. But there are also a few points to consider when caring for cacti. Although the requirements vary between the species, there are a few tips and tricks for fertilizing and watering that must be observed so that the small green cactus on the balcony can sometimes become a really big one.
Watering cacti correctly
Cacti need water regularly, especially during the growth and flowering period in spring and summer.However, it should not be watered too often and waterlogging should be avoided at all costs, otherwise there is an increased risk of rot. The substrate should be (almost) completely dry before watering again.
Water indoor cacti
In the case of indoor cacti, you can stimulate growth in spring by spraying them over. About a week later, the plants are watered more vigorously. A rule of thumb says: During the growing season from March to September, water thoroughly. You can easily check this by stuffing. Do not water again until the substrate is completely dry. Coasters, bowls or planters can hold excess water or be used to water from below. Another tried and tested method is the damming method: Here you place the pot with the cactus in a larger container with water so that the pot is completely submerged. As soon as there are no more air bubbles, take the cactus out of the water and put it back in its place after it has drained well.
"Watering cacti in the garden
If the cacti are in the garden, it is advisable to ensure there is sufficient water supply, especially in the spring months. In summer you should water fairly regularly. However, only on sunny days or after longer periods of drought to avoid overwatering from later rain. At the change of season, the watering rhythm is gradually reduced. In winter, special attention should be paid to watering. On the one hand, there is an increased risk that the soil will become waterlogged and fungal infections will spread. Additional rain protection should therefore be installed. On the other hand, a dry period in the winter months promotes the flowering of many types of cacti in the following year. However, this can only be implemented for potted plants that overwinter under cover.
Fertilize cacti correctly
It's a common misconception that cacti don't need fertilizing. On the contrary, there are few plants that are as dependent on fertilization as cacti. Deficiency symptoms often appear late and can then no longer be quickly remedied. Timely fertilizing is therefore essential to be able to enjoy the plants for a long time.
Fertilize room cacti
In the case of indoor cacti, you should start fertilizing with a normal complete fertilizer dissolved in water about four to six weeks after the first overspray in spring. A liquid fertilizer like our Plantura organic room &Green plant fertilizer can be applied every second watering from spring to July. However, the dosage for cacti is reduced to just 1 ml per liter of irrigation water.
Fertilize cacti in the garden
Outside, coarse horn shavings can be added to the topsoil in the garden or to the substrate in the planter as a basic fertilizer. Nevertheless, you should additionally fertilize from March. In the months of April to June, a 14-day fertilization has proven itself. You can give between 20 and 30 grams of a complete fertilizer (e.g. blue grain) per square meter. The commercially available liquid fertilizers (usually: 1% nutrient solution) should be watered regularly. In July, it is advisable to only fertilize the plants lightly. It is also beneficial to finish off with a potassium fertilizer (Kalimagnesia 20 g/m2) in August at the end of the season. As a result, the plants harden well and are well prepared for the coming winter.
If you want to know more about caring for your plants, here are the 5 best tips for caring for cacti and succulents.