White clover is a low, creeping perennial legume, 6 to 18 inches, grown as a living mulch, a cover crop, a lawn companion and pollinator forage. It fixes nitrogen through its root nodules, which feeds the plants around it and the crop that follows, and its white flower heads feed honeybees and bumblebees from late spring to fall. It is what the old lawns were full of before broadleaf herbicides took it out, and it is coming back in them.
Sow it shallow on firmed, raked soil in early spring or late summer, about a quarter pound per 1,000 square feet alone or an ounce or two per 1,000 overseeded into a lawn, and keep it moist until it is up. It takes mowing and foot traffic, regrows from the creeping stems, and stays green through drought that browns a grass lawn. The dwarf microclover types stay shorter and flower less.
As a cover crop between vegetables or under tall crops like corn and tomatoes, sow it once the main crop is established and cut or turn it in at flowering to return the nitrogen. It persists several years and self-seeds. Rabbits and deer graze it, which in a lawn is no loss, and it is a host plant for several small blue butterflies. Native to Europe and naturalised everywhere. Hardy in zones 3 to 9.
Rust
Orange to brown raised pustules on the undersides of leaves, with yellow spotting on the upper surface. Heavy infections cause leaves to yellow and drop.
Remove and destroy infected leaves. Avoid overhead watering and improve air circulation. Apply a sulfur or copper-based fungicide if it spreads. Clear plant debris in fall.
Southern Anthracnose
Dark sunken lesions on stems and petioles, often girdling and blackening the crown; plants wilt and collapse in patches during warm, wet weather.
Plant resistant varieties, ensure good drainage, and avoid dense overcrowded stands. Remove infected plants and rotate to non-legume cover for a season.
Powdery mildew
White or grey powdery coating on leaves - usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.