Bulbous Buttercup - Weed of the Week

What’s Up, Bulbous Buttercup?

We can all remember picking those tiny, yellow flowers and holding them under our friends’ chins to see if they “like butter.” Spotting buttercups in your lawns and pastures is sure to bring back childhood memories, but for some, the sight of it might not be as joyous.

Bulbous Buttercup Identification

Bulbous buttercup (Ranunculus bulbosus) is a perennial weed prevalent in pastures and hayfields, and occasionally, in lawns and gardens. It produces bright yellow flowers with cup-shaped petals glistened by a shiny upper surface when held against sunlight – and causing a reflection under our chins.  

Two closely related species are creeping buttercup (Ranunculus repens) and tall buttercup (Ranunculus acris). However, bulbous buttercups have a characteristic bulb-shaped base, referred to as ‘corm,’ just beneath the soil surface and reflexed or curved sepals that are pointed towards the stem.

Controls for Bulbous Buttercup

It comes to bloom from mid-April to May and are considered to be toxic to animals, especially horses, by virtue of a toxic glycoside called ranunculin. They tend to grow in nutrient-deficient soils and can be managed culturally by improving the growing conditions.

Seeds germinate during fall months forming rosettes that can remain dormant in the fields during winter months. Shoots from the corm emerge as the soil starts to warm up during early spring.  Tank-mixtures containing both 2,4-D and dicamba (several formulations) along with a surfactant provide good control when applied in early spring while the rosettes are actively growing and getting ready to bloom.