Succulent species of Euphorbia are not challenging to grow, provided that they are kept within their habitat preferences. Species that occur naturally in the summer-rainfall areas grow actively when water is available between spring and autumn and rest during the cooler winter months, when they should be kept dry. Similarly, species occurring in winter-rainfall areas prefer water only in the winter months and should be kept dry in summer. Euphorbia rhombifolia is predominantly in the winter-rainfall regions, although some forms also fall within the summer-rainfall regions. To improve the likelihood of success in cultivation, the grower should find out in which region the form to be cultivated occurs.

Seed is the easiest method of propagation, but plants can also be propagated from cuttings. Euphorbia seeds can be collected by picking ripe fruit and storing the capsules in a cloth or brown paper bag and leaving these in a dry, warm place to dry out. When the seeds are ripe, the capsule will release them through dehiscence, the bag will catch the seeds as they are ejected from the capsule and they can be prepared and sown in a tray of seedling medium. To ensure optimum viability, seeds should not be stored for longer than two years and can be planted within a month after they are released.

A seedling mixture containing hydroponic peat/perlite/vermiculite (in the ratio 2:1:3 or 2:1:4) can be used to germinate seed. This mixture is well aerated, retains moisture well and does not become waterlogged. The seedling mixture can be added to fill 15 mm of the rim of the pot and then flattened. The seeds should be carefully laid out on the mixture and an additional 2-4 mm of the same mixture used to cover them. The mixture should be drenched overnight with water containing fungicide and moved to a shady, warm area the next morning. Watering can be repeated after a week or two to avoid the upper layers from drying out. Seeds will take approximately 14 days to germinate, followed by a period of rapid growth. Once several leaves have emerged, plants can be repotted into normal soil. Euphorbias prefer loamy soils.

Many species of Euphorbia can be easily propagated from cuttings, which involves cutting where the branch is constricted at the base and allowing the cutting to sit and dry for a period of 2-4 weeks. Once planted in well-drained loamy soil, it will soon begin to root. The cutting can be stabilized using stones, to prevent movement which might result in plant damage. The cutting should be watered frequently during this period.

Euphorbia rhombifolia can be grown outdoors as an ornamental plant, positioned in a sunny area, against a north-facing wall as is done with many of the larger species of Euphorbia. The larger forms can also be used to create barricades or barriers as mentioned under uses above.

Euphorbia plants are typically disease free. While insects can be a slight problem in habitat, in cultivation this can be prevented by treating plants with poison containing the active ingredient Imidacloprid. In cultivation, Euphorbia species are prone to infection by the red spider mite which leads to plant cell death, resulting in an unsightly brown colouration in plants. In habitat, some of the larger Euphorbia species are parasitized by other plants.