Euphorbia

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Description:Euphorbiaceae is the name given to one of the largest families in the plant world, sometimes known as spurges.

It includes around 300 genera and 7,500 species, and of these around 870 are regarded as succulent. There are also countless hybrids of Euphorbia milii, some of great horticultural interest, as well as hardy species suitable for the garden or rockery. Many species have a milky latex which exudes copiously when cut, and is more or less caustic. This does not apply to the Jatrophas and Cnidoscolus which have a clear sap, but on the other hand some species in the latter genus have stinging hairs on the leaves and stem and need to be handled with care.CultivationLight. Succulent euphorbias need to grow in a place that is always bright, although this does not necessarily mean full midday sun! In habitat many euphorbias survive in full sun, but the roots are usually in a relatively cool soil often under rocks. In a pot on a south-facing windowsill, the soil can be much warmer.Some euphorbias remember the seasons of the southern hemisphere and grow in our winter months. For these we recommend artificial lights to supplement normal daylight, programmed to switch on an hour before sunset and remain on for up to 4 hours. Soil and Feeding.The soil performs three basic functions for plants: 1. The soil should give the plants a chance to root down and hold firm. In cultivation, this means the soil must not be too dense and prevent the roots penetrating. Furthermore, the soil must be well-drained so that surplus water can run away and so avoid root rot. 2. The soil needs hold a certain amount of moisture for use by the plants. 3. Finally the soil should provide the plants with necessary nutrients for the growing season. Plants in pots rapidly exhaust the soil and need regular feeding or repotting when required.After repotting, plants get all the nutrients they need from the new soil, but they soon use them up and need feeding. There are two main groups of fertilizer which differ in content. The so-called complete fertilizers contain nitrogen (N), phosphates (P) and potash (K). It is preferable to choose fertilizers with a low nitrogen content, but as the composition of all fertilizers varies considerably, it is best to vary the brand from time to time to avoid a deficiency of any particular component. Complete fertilizers also contain trace elements besides the normal components. These are required by plants, but with sufficient use of complete fertilizers and regular repotting, it is rarely necessary to use special fertilizers with these trace elements. However if you feel the need to use trace elements, please carefully follow the instructions, as an overdose can kill the plants. During the growing season regular but light fertilizing is recommended. Repotting small or slow-growing species is not necessary every year. Faster-growing species, however, can exhaust the soil after a year, despite regular feeding, although increasing the dose can delay the necessity to repot. However the danger of this system is that the plants can become torpid and susceptible to diseaseWatering. The idea that succulents grow in dry places is not quite correct. The majority grows in areas where water may not be available in certain periods or only as fog or dew. As far as possible, the requirements of individual species need to be considered. When it is hot and plants are growing, they may need as much water as ordinary plants.The choice of pot has a bearing on watering. Basically there are two types: 1. Unglazed earthenware pots. These allow water to evaporate through the sides, and also allow air to reach the roots, discouraging rot, a particular advantage for moisture sensitive species. Roots can however be damaged by cold due to evaporation. 2. Glazed earthenware and plastic pots prevent evaporation through the sides. This means they need less watering, but increase the risk of roots being damaged by excess moisture. Plastic pots can also get very hot in the sun and cause roots to be burnt.The golden rules for euphorbias are as follows: 1. If in doubt, don't water! 2. Just because euphorbias can survive drought, does not mean that they need it. In fact in the growing season regular and copious watering is required. 3. Most species do not appreciate dust dry soil in the resting season, and need a little water from below, or even carefully from above. 4. It is better to water heavily once, than give little drops often. Heavy watering wets the whole pot of soil encouraging a healthy root growth. 5. It helps to add more drainage material to the soil of moisture-sensitive species when potting. The best time to water in the warm season is evening as plants take up more water when it is cool, and less water evaporates away. Early morning watering is also acceptable and may even be better in the winter months.