Turnera buttercup (Turnera ulmifolia) is a fast-growing evergreen shrub that some consider a weed due to its reseeding habit and its ability to thrive in almost any location. This plant's saving grace is its attractive round form and the 2-inch buttercup-like flowers that bloom during the hottest parts of the summer.
- Plant Turnera buttercup in well-draining, fertile soil with full sun or light shade for the best results. It can tolerate almost all variations of sun exposure and different soils as long as they drain well, as well as salty air or water. If you are looking for a mass planting, space plants 18 inches apart; otherwise, plant single specimens two to three feet apart.
- Keep the soil moist throughout the plant's first growing season. It should survive well on one inch of water per week, by rain or by hand, although it may require more in hot, dry weather. After the first growing season it is very drought-tolerant and only requires water during extended droughts of a month or more.
- Scatter 1/2 cup of slow-release 10-10-10 granular fertilizer evenly around the plant in early spring, starting six inches from its base and extending out two to three times the length of the branches. Do not let fertilizer touch the foliage as it could burn the plant. Water over the fertilizer to help settle it into the ground. Apply another round of fertilizer of the same strength in mid-summer. In the plant's first year, wait until it starts growing vigorously before fertilizing once in summer.
- Prune in late winter or early spring, while the plant is not flowering, with sharp pruning shears, clipping back brown or overgrown branches to a leaf node within the canopy to maintain the shrub's rounded shape. This plant does not require pruning to flower or thrive, but it will make for a bushier and more attractive specimen if you do so.
- Watch for leafminers, which can burrow and eat holes in the leaves. Turnera buttercup has few disease or pest problems, but this is one of them. Prune off damaged leaves as you see them. In most cases these outbreaks are short-lived and only cause cosmetic damage because of the many natural predators of leafminers. Insecticides are not all that effective as they also kill the predators.