Prairie Dropseed

Prairie dropseed loosens into a flattened mound rather than lodging outright, losing its crisp fountain shape. Grown lean and in full sun the mound stays dense and self-supporting.

A clump that opens and sprawls from the middle, tall stems leaning or splaying outward, and soft floppy growth - worst in fertile or moist soil, in shadier sites, and after heavy rain or wind.

The fix is cultural, not chemical. Stop feeding, cut back on water, move the plant into more sun, and divide and replant it into leaner soil. A grass that flops every year in the same spot is in the wrong place or the wrong soil.

Grow it lean and in full sun: no fertilizer, average-to-poor well-drained soil, and enough light for firm, dense, upright growth. Where a sturdy upright cultivar exists for the species, choose it. Siting a tall grass among supportive prairie companions also helps keep it standing.

Not a pest but a cultural problem, and the commonest ornamental complaint about tall grasses. Rich or fertilized soil, too much water, or too much shade all produce soft, leggy growth, and the clump then opens and splays outward from the center, or the tall stems lean and lodge after a storm. The upright form - the whole reason you planted it - is lost for the season.

Uncommon in this drought-adapted grass - it only happens in heavy, soggy, poorly drained ground, and mainly over winter.

A plant that fails to green up or emerge in spring when everything around it does - the most common way this gets discovered, and by then it is already too late. Stems that wilt, blacken, and collapse in wet weather while the soil is clearly damp rather than dry. A crown that is soft, dark, brown, or mushy when you press or lift it, sometimes with a foul smell, instead of firm and pale. New growth that pulls away from the crown with almost no resistance. Clumps browning and going hollow in the middle while the outer growth stays alive. In stands and cover crops, patches wilting, yellowing, and thinning out after wet spells or over a mild wet winter.

There is usually no cure once the crown itself has rotted: the plant is lost, and the job is to save what you can and fix the site. Lift it, cut away every soft, dark, rotted part with a clean blade back to firm tissue, and replant only healthy divisions or firm outer growth into fresh, sharply drained soil or medium. On potted and specialist plants, repotting into fresh airy medium and keeping them drier with better airflow gives the best chance, though a badly rotted crown is usually beyond saving. Bin the rotted material rather than composting it. Replant somewhere better drained rather than back into the same wet spot - or start again from seed, cuttings, or self-sown seedlings, which is the realistic option for anything that resents being moved at all.

Drainage and airflow at the crown are everything. Match the plant to the site first: a dry-adapted perennial planted in heavy or enriched ground is on borrowed time whatever else you do. In wet or clay soil, plant on a slope, berm, raised bed, or gritty rock-garden site so water drains away from the crown rather than standing over it. Set plants at the right depth - never bury the crown - and keep mulch, dead leaves, and debris pulled back from it rather than piled against it, since damp material resting on the crown is a common trigger. Do not overwater, and ease right off during dormancy, when a resting plant wants to be barely damp rather than wet. Give crowded plantings enough space and airflow to dry out, and do not sow a stand too thickly. In cold, wet climates, divide in spring rather than fall, so plants are not recovering from surgery through the wettest months.

Crown rot is the rotting of a plant at the crown - the growing point where the stems meet the roots, right at or just below soil level. Soil fungi and water molds that live in most ground attack that tissue whenever it sits wet, cold, and airless, and because the crown is the one part a perennial cannot regrow from, losing it usually means losing the plant. It is above all a winter problem: a plant that survives hard frost perfectly well in dry ground rots out in a wet one, and the classic story is a perennial that simply never comes back in spring. Dry-adapted plants growing in heavy or over-improved soil are the most vulnerable, along with anything that has mulch, wet leaves, or piled debris sitting against the crown, and anything planted too deep.

The fine foliage shows flecking readily but the plant is unbothered. Clean the old growth out at the annual cut-back and it does not carry over.

Orange to rusty-brown flecks, spots or streaks on the leaves, often raised and powdery on the undersides, worst in muggy weather and on crowded, shaded or poorly ventilated plants.

Remove affected foliage and improve airflow. This is almost always cosmetic and outgrown, so fungicide is rarely warranted.

Space plants for airflow, grow them in full sun, and avoid overhead watering. Remove the old foliage at the annual cut-back, since spores carry over on last year's leaves.

A minor fungal leaf disease that raises orange to rusty-brown pustules on the foliage in humid, crowded, poorly ventilated conditions. On a tough, well-sited plant it is cosmetic - it marks the leaves late in the season and the plant grows straight through it - and it is rarely worth treating.