Waterlogging

What you see

Sudden yellowing of the lower leaves, wilting despite wet soil, leaf drop and soft blackening at the stem base. Roots are dark, soft and smell sour. Water stands on the surface long after rain.

Conditions

Compacted or clay soil, a hardpan under the topsoil, a high water table, or pots without working drainage. Roots need oxygen; standing water excludes it and they suffocate within days.

Treatment

Stop watering. Improve surface drainage, spike or fork compacted ground, and lift pots off saucers onto feet. Cut back top growth to reduce demand on damaged roots. Do not feed a waterlogged plant.

Prevention

Raise beds, add organic matter to open heavy soil, and break up any compacted layer. Choose plants suited to wet ground where drainage cannot be fixed.

Months: November, December, January, February, March

Plants

Lavender, Rosemary, Tomato, Orange, Lemon, Tangerine, Strawberry, Rose, Olive, Basil

Remedies

Mulch

The thing people get wrong

Waterlogged plants wilt, which sends almost everybody to fetch more water. The single most useful diagnostic habit in a garden is to push a finger into the soil before watering anything that looks stressed - wilting in wet soil is a completely different problem from wilting in dry soil, and the treatments are opposite. Waterlogging is also the gateway to Phytophthora, so fixing it prevents a real disease as well.