Having seen a number of people taking an interest in growing cacti and succulents during the recent Cacti and Succulent Society show I have decided to write on the basic care of cacti and succulents based on my experience of growing these plants in Manila.
Most books you see in the bookstores relating to the subject of cacti and succulents are written by growers from temperate climates so that there are differences in the culture and care of these plants when they are grown here in our tropical climate.
There are tens of thousands of species and varieties of cacti and succulents available to the collector and they come from many varied environments ranging from arid mountains to hot and dry lowland forests and deserts. One of the basic things to consider when collecting and caring for your plants is to take time to research about the plants, the environment where they grow in the wild and their place of origin. For example, Madagascan lowland succulents whether they are from the genera aloe, alluaudia, didieria, euphorbia, kalanchoe, pachypodium or other succulent families seems to do very well here because of similarities in our tropical environments except that here in the Philippines rainfall is much more frequent so that the plants must be protected from getting too much water.
Similarly, plants from tropical Africa and India also do very well here in our tropical environment. On the other hand, plants such as Aloe polyphylla, which come from the snow-covered mountains of Lesotho, do not thrive in our hot and humid environment. Based on my experience, Medusoid euphorbias such as E. decepta, E. ramiglans, E. esculenta, etc. from South Africa where they have a dry winter rest period do not seem to last very long here in our humid tropical weather. They seem to rot especially during the rainy season when humidity levels become very high and there is much less sunshine. As for the cacti, fraileas, echinopsis, gymnocalycium, cereus, some opuntia and notocactus species seem to do very well here in the lowlands while ferocacti, echinocacti, cephalocereus, rebutias, sulcorebutias, to name a few do not seem to do as well.
Many cacti, however, seem to do very well in the highlands such as in Baguio and Benguet. One reason for this may be because the temperature in the highlands range from the mid-10s in the evenings to the mid-20s during the day and this day and night temperature difference, according to a study by Nobel and Gibson, is optimal for most cacti to be able to fully utilize the so-called Crassulean Acid Metabolism or CAM.
Beginners should choose plants that are easier to grow here in the lowlands and then graduate to the more difficult ones so that the potential collector/hobbyist will not become discouraged by rotting and dying plants. One of the first questions often asked by beginners is "What kind of growing medium should I use?"
Surprisingly, most cacti and succulent plants are not as fussy with their growing medium even though they come from a number of different places, growing in different types of soils. As long as the growing medium has great drainage, which also provides good aeration for the roots and enough nutrients, the plants will most likely thrive in them. I have seen beautifully grown cacti and succulents planted in very different mediums such as coconut coir and sand mixture, loam and sand mix or even in pure leaf mould. A good standard mixture is 1/3 good garden loam, 1/3 well rotted compost, and 1/3 sharp sand.
Never use coral or sea sand because they contain high concentrations of salts, which can burn and damage the plant’s delicate roots. Also, never use very fine sand, which can compact the growing medium and suffocate the roots of the plant.
Plastic or clay containers are fine for cacti and succulents as long as they have drainage holes. The frequency of watering will depend very much on the type and size of container the plant is being grown in. The rule of thumb when watering plants is to water only when the medium is almost dry. Do not let the medium dry thoroughly because although cacti and succulents may survive long periods of drought, the fine roots of the plants die off when the plant is kept too dry and this can cause the dead roots to rot when the plant is watered afterwards. This is especially true when the plant is pot-bound and the roots have formed a tight root ball inside the pot. In the wild the plants have free root run and the roots are not confined so that they don’t rot after a heavy downpour following a long drought.
In some growing media such as coco coir and sand mixes and pure leaf mould, the growing medium becomes very hard to re-wet when they dry out and even when they are given a large amount of water, the water will just flow along the side of the container and down the drainage leaving a large portion of the plant roots dry and dying. When watering your plants, water thoroughly so that the entire root ball of the plant becomes wet and not just the surface. If the plants are not watered enough they will not be able to take up water with their roots and they will hardly grow at all.
Newly potted plants do not need to be fertilized for several months but as the plants deplete the nutrients from the soil mixture, regular supplementary feeding during the growing season is a must to be able to grow healthy plants. A dilute of low nitrogen liquid fertilizer once every two weeks or a slow release fertilizer such as Osmocote is a good way to feed your plants. Nutrient -hungry plants such as tropical Indian euphorbias and fast-growing pachypodiums such as Pachypodium lamerei and geayi need more frequent feeding during their growing period, which is usually during the summer months. Slower-growing plants such as ariocarpus, pachypodium brevicaule and some rare Somalian euphorbias will need much less fertilizing and less frequent watering.
One of the most important factors in growing beautiful and healthy plants is sunlight. It can never be overemphasized that to grow beautiful and compact plants with nice spines, color and form enough sunlight must be given to the plants.
Different plants have different sunlight requirements. Haworthias like bright filtered sunlight while the very spiny or hairy and blue green colored cacti and succulents can take a good amount of full sunlight throughout the day. Plants that lack enough sunlight will look misshapen with weak spines, uncharacteristic bright green colors, soft and etiolated stems.
Some cacti I would recommend for beginners are Cereus peruvianus (these grow to tree-size dimensions), fraileas (the only cacti which does not seem to mind a bit of overwatering) gymnocalycium species, notocactus magnificus, opuntia ficus indica, all the lophophora species or peyote the sacred cactus of the Mexican Indians, echinopsis species and hybrids (these plants are nutrient-hungry plants and should be fertilized frequently), a number of mammillarias. Of the succulents, most tropical aloes, tropical euphorbias such as Euphorbia tortilis, Euphorbia ingens, Euphorbia viguieri, Euphorbia millii, etc., a number of spiny branching euphorbias such as Euphorbia golisana, Euphorbia greenwayi, Euphorbia petricola, etc. also do very well in our tropical climate. Haworthias and gasterias also do well here in the lowlands as well as most pachypodiums, monadeniums (the relatives of euphorbias) and most agaves and sansevierias – the list goes on and on so that collecting cacti and succulents can never really be boring.
Growing these plants well can be a challenge and is very rewarding when one is successful.