Does Helenium spread easily?
Helenium is a clumping perennial, so is well behaved, not spreading quickly. However, after 3- to 4-years the clump gets large and will benefit from dividing. Divide Helenium in spring making smaller, new plants to grow in other parts of your yard. Heleniums generally need staking to keep them upright, but to avoid this you can give them the ‘Chelsea chop’, in May, or cut them back to 30cm (12in) in mid-July. This delays flowering slightly but keeps plants more compact so you can enjoy the flowers on neat, unstaked plants.
What problems can Helenium have?
Common Name(s): Helenium is a genus of annuals and herbaceous perennials having yellow or orange-to-red daisy-like flowers. The genus is named after Helen of Troy. Potential problems: powdery mildew, leaf spot, and rust. In high wind or heavy rain, the stalks may need support. Helenium and Rudbeckia are two late-summer stars that bring rich colour to borders just as other blooms start to fade. Rudbeckia is known for its bold yellow petals and dark central cone, while Helenium (also called sneezeweed) often shows off multi-toned petals with a rounded centre.
Is Helenium poisonous?
Animals eat sneezeweed during the summer and fall, when other forage is scarce or has become less palatable. All plant parts are poisonous. The chemicals in sneezeweed can poison livestock, particularly sheep. The sesquiterpene lactone helenalin found in sneezeweed also has been found to be poisonous to fish and dogs. It is a crystalline substance with the chemical formula C20H25O5, which irritates mucous membranes.